Emissions of Materials

Benchmark Assessment
for Residential Construction
Table of Contents
Acknowledgments ...................................................................... 1
Executive Summary..................................................................... 2
Putting Material Carbon
Emissions into Context................................................................. 4
Previous Studies of Material Carbon Emissions............................................... 5

Emissions of Materials Benchmark

Assessment for Residential Construction (EMBARC)........................................ 6

Methodology.............................................................................. 7
2.1 New Home Starts.................................................................................. 8

2.2 Sample House Plans............................................................................. 8

2.3 Material Carbon

Emissions (MCE) Calculations...................................................................... 9

2.3.1 BEAM Methodology........................................................................... 9

2.3.2 Carbon Storage............................................................................... 10

2.3.3 Cradle to Gate Focus on Structural,

Enclosure & Interior Surface Materials.......................................................... 12

2.3.4 BEAM Limitations............................................................................. 14

Results & Discussion.................................................................. 15

3.1 Material Carbon Emissions (MCE)
and Material Carbon Intensity (MCI)............................................................ 15

3.1.1 Housing Typology and MCI................................................................ 20

3.1.2 Combining Material and

Operational Emissions: Carbon Use Intensity................................................ 21

3.2 Material Analysis.................................................................................24

4. Effects of Material
Substitutions on MCI................................................................................ 32

Conclusions.............................................................................. 37
Recommendations for Policy Makers............................................ 40
Industry Recommendations........................................................ 45
Endnotes................................................................................. 46
 Acknowledgments
Passive Buildings Canada is Canada’s first national that offer benefits beyond carbon reduction such as
non-profit organization supporting the passive house improving people’s health, creating new green jobs,
community to build a more sustainable Canada and boosting urban resilience, and contributing to a fair
planet. We welcome a diversity of approaches and society.
voices to connect, share knowledge, and promote
passive house projects. The team would like to thank Gaby Kalapos at the
Clean Air Partnership for her insights, support
Builders for Climate Action is creating tools, and assistance in working with the municipalities
research and resources to support practitioners of the GTHA.
and policy makers in making zero carbon buildings.
Chris Magwood, Erik Bowden and Mélanie Trottier The team would also like to express their sincere
prepared this report on behalf of BfCA. appreciation to Eve Treadaway for her work in
organizing the data for this study and Javaria Ahmed
This report has been made possible by a grant from for her assistance in entering building plans into
The Atmospheric Fund, a regional climate agency BEAM.
that invests in low-carbon solutions for the Greater
Toronto and Hamilton Area and helps scale them Thanks to reviewers: Ryan Zizzo, Founder & CEO,
up for broad implementation. TAF are experienced Mantle Developments; Kelly Alvarez Doran, MASS
leaders and collaborate with stakeholders in the Design Group and Associate Professor, University
private, public and non-profit sectors who have ideas of Toronto; Lisa King, Senior Policy Planner, City of
and opportunities for reducing carbon emissions. TAF Toronto; and Roya Khaleeli, Director, Sustainability
advances the most promising concepts by investing, Innovation - Minto Communities Canada.
providing grants, influencing policies and running
Thanks as well to everyone who provided feedback
programs. TAF is particularly interested in ideas
and comments, who are too numerous to name.

This report has been made possible in part thanks to data and advice from:
• Arista Homes Municipalities of:
• Country Homes • Burlington
• Chatsworth Fine Homes • Halton Hills
• Geometra Designs • Milton
• Minto Communities • Oakville
• OPUS Homes • Brampton
• Sustainable TO. • Caledon
• Westpark Homes • Mississauga
Cities and Regional Municipalities of:
• Durham
• Hamilton
• Toronto
• York

Suggested citation: Magwood, C., Bowden, E., Trottier, M. Emissions of Materials Benchmark Assessment for
Residential Construction Report (2022). Passive Buildings Canada and Builders for Climate Action.

Report layout and design by FrolicDesign.ca

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 1
 Executive Summary

Rich Data Set Material Carbon Intensity

EMBARC generated a rich data set, representing Material carbon intensity (MCI) was calculated by
503 as-built homes of three key typologies: dividing total emissions by floor area, to enable
single detached, semi-detached and townhouses. comparisons between units of different sizes.
Together, these housing types represent an
average of 16,400 new homes built annually in MCI was calculated using various definitions of floor
the region. area, with the weighted average results:

Building Emissions Accounting for Materials Gross floor area — 154 kg CO2e/m2
The BEAM (Building Emissions Accounting for Heated floor area — 189 kg CO2e/m2
Materials) estimator tool was used to assess GHG Habitable floor area — 225 kg CO2e/m2
emissions and carbon storage for building materials
that make up the structure, enclosure and main Depending on the floor area definition, each of
finishes, based on results from Environmental the three housing typologies could be the best or
Product Declarations. Emissions from raw the worst, indicating the importance of accurately
material harvesting, transportation to factory and defining the parameters for MCI.
manufacturing (A1-A3) were considered. Mechanical,
electrical and plumbing materials, millwork, stairs, Based on heated floor area, the lowest MCI result
doors and surface finishes were not calculated. was 116 kg CO2e/m2 and the highest was 561 kg
CO2e/m2. The 189 kg CO2e/m2 average MCI for
heated floor area was higher than the 150 kg CO2e/
503 homes = 20,122 tonnes of emissions
m2 average from previous studies, due largely
Material carbon emissions (MCE) across the study’s to bigger garages and more use of high emission
sample of 503 as-built housing units totalled an cladding (brick) and insulation (XPS foam).
estimated 20,122 tons, with an average of 40 t CO2e
per unit. The lowest emitting home was responsible
for 9.5 t CO2e and the highest 827.1 t CO2e.
High Emission Materials
73 percent of all material carbon emissions in the
16,400 homes = 840,000 tonnes of emissions
study come ftrom just three material categories:
Extrapolating the study’s average values to all new concrete (33 percent for foundation walls, slabs and
low-rise homes built each year in the GTHA, the total footings), insulation (26.1 percent for foundations,
annual MCE may be around 840,000 t CO2e annually. walls and roofs) and exterior cladding (13.4 percent).
This is equivalent to the emissions from more than Efforts to reduce MCEs should be concentrated on
183,000 automobiles. these material categories.
As the MCE measured in this study may represent as
little as 50 percent of the total MCE for these building
typologies, due to the exclusion of MEP equipment,
appliances, finishes and millwork, a possible impact
of 1.75 Mt (megatonnes) of MCE is likely arising from
new home construction.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 2
 We Can Make a Difference The New Direction
Material substitutions were explored for a home The researchers recommend that policy makers
with heated floor area MCI of 116 kg CO2e/ and the home building sector begin to regularly
m2. Using the “best available materials” (widely measure MCE and MCI for new homes, and
available, affordable and code-compliant), this implement voluntary thresholds in line with the
could be reduced to 56.5 kg CO2e/m2. If all new average results from this study. Regulation of MCE
homes in the GTHA used the “best available may enable region-wide emission reductions of
materials” this would result in approximately 250,000 to 1,000,000 t CO2e annually.
573,000 t CO2e fewer emissions annually.

Using the “best possible materials” (feasible but

unconventional), this could be further reduced to
-54.6 kg CO2e/m2, indicating that homes could
become sites of net carbon storage, rather than
net emissions.

Using the “best possible materials” would result in

the reduction of roughly 1,065,000 t CO2e. In this
hypothetical scenario, new Part 9 homes built in
the GTHA would pass beyond net zero carbon to
store around 225,000 tonnes of carbon from the
atmosphere during a single construction year.

Using the BEST

available materials we
can reduce emissions
by 50%

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 3
 Putting Material Carbon
Emissions into Context
Canada, and the entire world, is faced with a rapidly The very short amount of time available to meet
declining “carbon budget” within which we must Canada’s emission reduction targets of 40‑45 percent
function to stave off the worst effects of climate below 2005 levels by 20303 requires us to consider all
change. The United Nations has declared the climate of the emission impacts from the housing sector and
emergency “code red for humanity.”1 The Pan- focus effort on those sources of emissions that have the
Canadian Framework on Clean Growth and Climate greatest immediate impact on our remaining carbon
Change (PCF, 2016) identified the building sector as budget. In recent years, increased attention has been
one of the major contributors to GHG (greenhouse drawn to the emissions arising from building materials,
gas) emissions in Canada.2 To this end, improvements often referred to as “embodied carbon,” (this
in energy efficiency have been integrated into the report uses the more specific term “material carbon
National Building Code of Canada and the Ontario emissions”(MCE) to describe the cradle-to-gate phases
Building Code as well as municipal incentives and of life cycle assessment 4). Early research5 6, in this
voluntary green building standards in order to reduce field indicated that over the next two crucial decades
emissions from new homes. these emissions are likely to substantially outweigh the
operational emissions attributed to newly
constructed homes.

Remaining Global Emissions Budget

50

45
660 GtCO 2
(1.5°C, less than 50% Chance)
40
500 GtCO 2
Emissions from buildings
35 (1.5°C, 50% Chance) need to be reduced by
30 33%
50-67% to meet IPCC
1.5°C targets
25
50%
20

15
67%
340 GtCO 2
10 (1.5°C, 67 % Chance)

2020 2025 2030 2035 2040 2045 2050

PHASE OUT

Figure 1: Emission reduction pathways to meet IPCC 1.5C targets Adapted from Architecture 2030.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 4
 Previous Studies of Material Carbon Emissions
In 2021, Natural Resources Canada (NRCan) released high of 513 kilograms of emissions per square meter
the report “Achieving Real Net Zero Emission Homes”7 of heated floor area (kg CO2e/m2) to a low of -50 kg
establishing that material carbon emissions (MCE) CO2e/m2. The model using the most conventional
for new homes will outweigh operational carbon mix of materials showed 150 kg CO2e/m2 and the
emissions (OCE) for electrified homes using relatively model using materials with the lowest emission profile
clean electrical grids such as that in the Greater that are widely available and code compliant was
Toronto and Hamilton Area (GTHA) for almost 120 2 kg CO2e/m2.
years. At the highest levels of energy efficiency
proposed by codes, this imbalance extends to 166 In 2021, Builders for Climate Action worked with
years of OCE to equal MCE. According to these the cities of Nelson and Castlegar, BC, to examine
results, MCE would represent a large majority of the MCE of 34 as-built homes in the region9. The
a new home’s total emissions over the next few measured results included a high of 309 kg CO2e/m2
decades. Left unchecked, MCE is likely to undercut and a low of 72. The average across the 34 samples
the gains made in reducing operational emissions was 150 kg CO2e/m2. A local home that was not
over the past decade. included in the study but measured using the same
methodology matched the NRCan “best available
Using archetype home designs for a bungalow, materials” result of 2 kg CO2e/m2.
two-storey and row house the NRCan report used
four material palettes to reflect different MCE Both studies revealed that total MCE from new
outcomes: high, mid-range, best available and homes represents a significant, mostly overlooked
best possible materials. and unregulated, pool of GHGs. Nationally, an
average of 150 kg CO2e/m2 for all new housing
The study found that the average measured MCE for construction would represent total GHG emissions of
Tier 38 homes across five Canadian cities could vary 8.5 million tonnes annually based on average annual
widely based on these material selections, from a construction10.

Total Net

Canada-wide STORAGE

-50
Total Net
EMISSIONS
Total Net
EMISSIONS
Total Net
EMISSIONS
NRCAN Study Total Net2
kgC02e/m
2 150 513
Canada-wide
Canadian average of three
STORAGE

-50
Total Net2
kgC02e/m
EMISSIONS
Total Net2
kgC02e/m
EMISSIONS
kgC02e/m
2
Total Net
EMISSIONS
NRCAN
archetypesStudy
and 190 models kgC02e/m2
Best Possible 2
BestkgC0
Available
e/m 2
150
Moderate Carbon 513
High Carbon
kgC0 e/m
2

Materials
kgC0 e/m
Materials
2

Materials Materials
2 2
2

Canadian average of three

archetypes and 190 models Moderate Carbon High Carbon
Best Possible Best Available
Materials Materials Materials Materials

British Columbia Total Net

EMISSIONS
Total Net
EMISSIONS
Total Net
EMISSIONS
Nelson & Castlegar Study 72 150 309
British Columbia
34 as-built homes
kgC02e/m2
Total Net
EMISSIONS
kgC02e/m2
Total Net
EMISSIONS
kgC0 e/m2
Total2Net
EMISSIONS
Nelson & Castlegar Study
Lowest72
Carbon
kgC0 e/m 2
150
Average Carbon
kgC0 e/m 2
309
Highest Carbon
kgC0 e/m 2
Figure 2:
Result
2
Result
2
Result
2
Results of MCE studies
34 as-built homes
Lowest Carbon Average Carbon Highest Carbon
Result Result Result
Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 5
 TERMINOLOGY
MCE  Material Carbon Emissions

Emissions of Materials Benchmark

Assessment for Residential Construction (EMBARC)
The EMBARC study examines MCE in the GTHA using This report offers many insights into MCE from Part
a large sample of as-built new Part 9 homes and 9 homes and ways in which it can be dramatically
the same methodology as the NRCan and Nelson/ reduced. These emissions are considered “Scope
Castlegar studies. The intent of the study is to provide 3” – generated by manufacturers across North
an understanding of the total impact of MCE from new America (and indeed around the world) – and are
Part 9 homes on the region’s emissions and provide therefore not typically addressed by municipalities.
decision makers – including policymakers, developers, However, decisions made by municipal policymakers
home designers and builders, as well as homeowners and the local building sector can have significant
– with insights on how this MCE can most effectively and immediate impacts on these emissions.
be reduced in future construction of the GTHA’s Addressing MCE at the regional level is an example
housing stock. of acting locally to make important impacts globally,
and we look forward to sharing and discussing
the recommendations in this report widely with
EMBARC generated a rich data set, stakeholders in the region to encourage action
representing 503 as-built homes of three on MCEs.
key typologies: single detached, semi-
detached and townhouses. Together, On a positive note, this study does not only point out
these housing types represent an average a problem, it also provides clear recommendations for
of 16,400 new homes built annually in how to minimize the problem. Unusual for a report on

?
the region, based on data from 2017- climate change, this study suggests that new homes
2020 collected from municipalities by the could potentially become sites of negative emissions,11
research team. with atmospheric carbon stored in building materials
outweighing all associated manufacturing emissions
and providing a net reduction in atmospheric carbon.
While it is beyond the scope of this report to consider
the future supply chains necessary for a carbon-storing
homebuilding sector, we want to be sure to point
toward the economic potential of using the vast array
of regionally available carbon-storing raw materials
in new regional manufacturing of building materials
and components. As there is much talk of post-
A detailed analysis of each set of home plans in the
pandemic “building back better” we can think of no
free software program BEAM (Building Emissions
better way to do so than by lowering CO2 levels in the
Accounting for Materials) enabled the study team
atmosphere while making energy efficient and healthy
to generate total MCE for each home, as well as a
buildings out of materials that boost all sectors of our
material-by-material breakdown.
regional economy.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 6
 Methodology
The researchers chose to use the same methodology as earlier Canadian
studies of MCE, following the steps illustrated in Figure 3.

A1 A2 A3
+ +
Extraction of Transport of Processing into
Raw Materials Raw Material Building Products

M
BEA
EPD
S
TI O N
U LA
C A LC

BEAM estimator applies Standardized Environmental

EPD factors to individual
Product Declarations
home plans
(EPDs)

59
SAMPLE
59
house plans
represent
TOTAL
Material Carbon
HOUSE Emissions

PLANS 503
as-built homes
BEAM results for 59 sample
house plans from 8 developers

Figure 3. EMBARC study Extrapolation of results to

methodology diagram
annual construction of new
homes in GTHA

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 7
 2.1 New Home Starts The researchers analyzed 59 different plan sets which
represent 503 homes built in the GTHA region. Table 2
Each municipality in the GTHA was approached to shows a breakdown of the plan sets by typology
ascertain the number of new Part 9 homes constructed and built examples.
between 2017-2020, composed of three typologies:
Table 2. Plan sets and number of plan sets built
single detached, semi-detached and townhouses. The
annual average total is 16,428 units. The results for Building Plan count per Quantity of
each typology are shown in Table 1. Archetype archetype plans built

Table 1. Average annual new dwelling unit completions Single Detached 19 116
by building type and municipal region (GTHA, 2017-2020
annual average). Semi-detached 5 38
Average annual new Part 9 Townhouse 35 349
dwelling unit completions in GTHA
Total 59 503
Municipal Single Semi- Town-
Total Single Detached 32% 23%
Region Detached detached house
Durham 1,452 84 989 2525 Semi-detached 8% 8%
Halton 1,188 169 1,036 2393 Townhouse 59% 69%
Hamilton 580 54 881 1515
The sample size is 3.1 percent of the total number of
Peel 2,165 419 1,137 3721
new single detached, semi-detached and townhouses
Toronto 1,122 92 570 1784 typically completed annually in the GTHA. This data
York 2,564 205 1,721 4490 set of homes is the largest sample in the world of MCE-
GTHA 9,071 1,023 6,334 16,428 analyzed residential buildings employing a consistent
% of methodology.
total units 55% 6% 39%
The study sample set acquired underrepresented single
detached homes by 23 percent and overrepresented
2.2 Sample House Plans townhouses by 21 percent. Where applicable, the
researchers adjusted for this in the calculations, as well
The researchers contacted developers and builders as for the discrepancy between the sample plan floor
across the GTHA with a request for Part 9 residential areas and the average floor areas for the GTHA for each
plans that met the criteria of the study. Eight of the three archetypes. Floor areas for the GTHA were
developers/builders in the region supplied plans for extracted from Milton building permits from 2017-
the study, with the majority sharing plans for numerous 2020, as no other municipality included floor area data
homes they have constructed in the GTHA between in their building reporting. While Natural Resources
2017 and 2020. Most of the shared plans represent Canada has national floor area statistics up to 2018,12
more than one constructed building. The researchers the researchers decided this was not regionally specific
were informed of the number of times each sample plan enough, thus Milton’s floor area values were chosen to
was actually constructed during the period of the study. represent all of the GTHA.13

59
SA M PL E
59
house plans
represent
H O US E
PL AN S 503
as-built homes

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 8
 TERMINOLOGY
MCE  Material Carbon Emissions

GWP  Global Warming Potential

BEAM  Building Emission Accounting for

Materials
2.3 Material Carbon EPD  Environmental Product Declarations

Emissions (MCE) Calculations

Each set of plans used in the study was entered into a tool from Natural Resources Canada. BEAM and
beta version of a spreadsheet application called BEAM MCE2 were developed specifically for Part 9
(Building Emission Accounting for Materials). BEAM residential construction and include all materials/
was developed by Builders for Climate Action and products used in residential applications for which
shares an overlapping database and methodology there was sufficient, reliable data available at the time
with the Material Carbon Emissions Estimator (MCE2) of the study.

M
BEA
EPD
S
IO N
UL AT
CA LC

Standardized Environmental BEAM estimator applies

Product Declarations EPD factors to individual
home plans
(EPDs)

2.3.1 BEAM Methodology

BEAM is based on a methodology common for GWP factors are quantities of GHG emissions
embodied carbon calculations. The Global Warming arising from specific life cycle stages, expressed in
Potential (GWP) factors for materials are gathered kilograms of carbon dioxide equivalent (kg CO2e)
from Environmental Product Declarations (EPDs), per given “functional unit” of a material or product
which are third-party certified reports prepared (e.g. 1 m3, 1 kg, 1 m2 , depending on the product).
according to ISO 14025 in addition to either EN BEAM calculations begin with entering the relevant
15804 or ISO 21930: 2017. 14 In some cases, an EPD building dimensions from the plan set, which are
must also conform to ISO 1407115. Where no EPDs then used as the basis for calculating material
exist for a product, BEAM uses an average GWP quantity estimations. Fields are provided in BEAM to
result from all applicable peer-reviewed life cycle further specify key dimensions and factors used to
assessments (LCAs) of the product. complete quantity estimations, such as R-value for
insulation, framing spacing, and concrete wall and
The GWP factors in BEAM are a sum of life floor thickness. With all material quantity information
cycle stages A1 (raw material acquisition), A2 entered, BEAM provides the GWP for every material
(transportation of raw materials to manufacturing in a given assembly. BEAM presents the user with
facility) and A3 (manufacturing emissions). This is an average GWP factor for all products in a given
often referred to as a “cradle to gate” analysis and material category, or allows for selecting the result
makes up the “material carbon emissions” that are for a particular product within the category. For the
the focus of this study.16 EMBARC study, average results were selected unless
there was a clear product name specified in the plans
and a corresponding EPD for that product in BEAM.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 9
 2.3.2 Carbon Storage
BEAM accounts for carbon storage in products that
contain biogenic materials sourced from agricultural
or forestry residues and recycling streams. In such
cases, the mass of biogenic material per functional
unit is determined according to the product EPD
or LCA and the mass of carbon within that biogenic
material is calculated based on chemical composition
analysis results from the Phyllis database17. The net
GWP emissions for the product is the result of the
A1-A3 carbon emissions minus the biogenic carbon
storage. The net emissions for some biogenic materials
therefore have a negative value when carbon storage
is greater than carbon emissions. These net negative
emissions materials are often termed “carbon-storing”
materials.

No carbon storage attributed

to virgin forest products
While there is a standard methodology in ISO 21930
for determining biogenic carbon storage credits for
products, there remain important and unresolved
concerns with current accounting methods related
to virgin forest products like lumber. Some of these
concerns include uncertainty about the amount of
carbon released from soils during logging operations;
the amount of carbon returning to the atmosphere
from roots, slash and mill waste; the amount of carbon
storage capacity lost when a growing tree is harvested;
and the lag time for newly planted trees to begin
absorbing significant amounts of atmospheric carbon
dioxide. These factors and others are being researched
and deliberated by experts from academia, the
forestry industry, the building industry, environmental
advocacy organizations, and LCA professions. Because
these critical issues were unresolved at the time of this
study, the BEAM version used for the study excluded
biogenic carbon storage for products made of raw
logged timbers (including framing lumber, plywood,
OSB and wood trusses and I-beams).

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 10
 The Positive Impact of Durable
Carbon Storage: Ton Year Accounting
While there is consensus that storing carbon for a out of the atmosphere and storing it for a period of
period of time has a mitigating impact on climate 46 years mitigates the climate damage from one ton
change, there has been considerable debate of CO2 emissions (the area in green).
about how to account for the value of temporary
carbon storage. The Moura Costa method18 of ton- The materials attributed carbon storage by BEAM
year accounting establishes the value of carbon have anticipated lifespans of at least 46 years
dioxide stored in durable products such as building and can thus be said to have at least the positive
materials. As shown in Figure 4, a one metric ton climate impact of their full carbon content. Many
of carbon dioxide emissions causes 46 ton-years of such materials will last longer than 46 years in a
radiative forcing damage to the climate over a 100- building, and may therefore increase the storage
year timeframe (the area in grey). Drawing one ton of value; materials removed from the building before
carbon dioxide reaching 46 years could have their carbon storage
value discounted accordingly (see Table 3).

1 ton
of CO2
emissions

46 T
on-y
e a rs
of Clim
ate D ama
g e (warming)
0 46 100
Years Years Years

Figure 4. Graphical representation of

Durable Biogenic the Moura Costa method to establish the
CARBON STORAGE carbon offset equivalence of biogenic
Equivalent Areas carbon storage in building materials.19
in Buildings
1 ton 46 Ton-years Adapted from Srubar et al., A
of CO2
Methodology for Build- ing-Based
removal
Embodied Carbon Offsetting (2021)
Climate Damage Avoided

Table 3. Examples of carbon offset value of biogenic The factors in Table 3 assume that 100 percent of the carbon
carbon for various time horizons. contained in the material will return to the atmosphere when
removed from the building. Any material reuse, recycling or
Ton Year Equivalency Factors for carbon capture (or a percentage of carbon materials put in
Biogenic Carbon landfill that do not decompose) would alter these scenarios
Biogenic Duration of Equivalent Offset accordingly, as any carbon that remains out of the atmosphere
Carbon Stored Storage of Present-day would continue to have a positive impact on the climate.
Emissions For a world with a rapidly dwindling carbon budget and
100 tons 1 year x 2.17% 2.17 tons ample opportunities for biogenic carbon storage in the built
environment, this methodology offers a great deal of potential
100 tons 20 years x 2.17% 43.4 tons to encourage this type of climate mitigation.
100 tons 1 ton
46 years x 2.17% 100 tons
100 tons 80 years x 2.17% 174 tons
of biogenic carbon OFFSETS
stored for 46 years
100 years
of damage
1 ton
Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 11
of biogenic carbon
released into
 2.3.3 Cradle to Gate Focus on Structural,
Enclosure & Interior Surface Materials
This study and the BEAM tool focus on lifecycle stages A1 to A3 emissions (defined in 2.3.1) because they
represent the majority of the life cycle GHG emissions from building products, typically accounting for
70-80 percent of life cycle emissions from buildings20. For the first 30 years of a building’s lifespan (that
is, before substantial repairs or replacements of materials occur), A1-A3 emissions account for over 90
percent of material emissions. Given the timelines we are facing for dramatically reducing emissions, this
methodology prioritizies the time value of addressing A1-A3 emissions.

Using the building plans, each material for each assembly in the building is selected, and the kg CO2e
results are calculated both for the assembly and for the whole building. Once all materials have been
selected, BEAM provides a total for Material Carbon Emissions (MCE) for the building in both kilograms
and tonnes of CO2e, as well as the Material Carbon Intensity (MCI) which is the MCE divided by the floor
area of the building in kilograms of CO2e per square meter (kg CO2e/m2).

This study, and the BEAM tool, focus on the main structural, enclosure and interior surface elements of a
new Part 9 home. Figure 5 shows the materials that are included in this study.

✔ Footings and slabs

✔ Foundation walls

✔ Structural elements
(posts and beams)

✔ Exterior walls

✔ Party walls (where

applicable)

✔ Exterior cladding

✔ Windows

✔ Interior walls

✔ Floors

✔ Ceilings

✔ Roof

Figure 5. Materials
included in the study.

12
 These elements of the building were
selected for four key reasons:

1 They represent the majority of the overall material mass

There is good quality EPD and LCA data available for all
2 common options in these categories

They typically have lifespans of at least 25-30 years and

3 often last as long as the building

There are meaningful, immediately available design

4 options and/or material substitutions available in each of
these areas that allow a home builder to substantially alter
the emissions profile of the building

By addressing the bulk of a new home’s emissions and focusing on

those areas in which significant reductions can be achieved, we
believe this approach maximizes the utility of the results.

Each set of plans was entered into BEAM by a member of the

Builders for Climate Action team, familiar with the software. A
review of each entry was conducted by a different team member to
ensure accuracy.

The BEAM calculations for each individual set of plans were then
compiled into a spreadsheet that enabled the researchers to
examine the results by home, typology, location, size, material
category and material type.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 13
2.3.4 BEAM Limitations
The results derived from BEAM should be considered estimates of emissions, and not definitive quantities.
Results from BEAM are similar in nature to those obtained from energy modeling software, from which
comparative results from different materials and strategies can be accurately derived, but from which actual
energy use may not be accurately predicted.

It is important to note that BEAM will underestimate the total emissions arising from materials for a new home
because a number of significant material categories are not currently considered within BEAM, including:

✘ Mechanical, electrical and plumbing (MEP) ✘ Fixtures and appliances. These are excluded
materials. These are excluded due to a lack of due to lack of available data and lack of meaningful
available EPD data and lack of meaningful substitutions substitutions. Many of the key components of fixtures
in each category. Material GHG emissions from MEP and appliances (steel, stainless steel, copper, porcelain)
could range from 40-75 kg CO2e/m2, which could add are known to have substantial MCE but few EPDs or LCA
an additional 26-49 percent to the average gross floor studies of specific products exist.
area MCI for homes in this study.21
✘ Millwork, stairs, cabinetry and trim. These
✘ Paints and surface finishes. These are excluded are excluded due to lack of available data and lack of
because the lifespan of these materials is typically meaningful substitutions.
shorter than the minimum 25 year lifespan required
for inclusion in BEAM. They do, however, contribute ✘ Decks, driveways, earth moving,
significantly to the MEC of a new house. A typical single excavations, and all site works. These are
detached house in this study has approximately 750 excluded due to the variability and complexity of
m2 of wall and ceiling area that would be painted, and adding these to the study.
an average interior paint (all coats) has emissions of 3.5
kg CO2e/m2, resulting in an additional 2.6 tonnes of
emissions or 6 percent of the average emissions for a
home of this size.22 Finishes for trim, doors
and millwork would add to this total.

It is possible that with all of

the above elements added
into MCE calculations, the
results in this study may
represent as little as 50
percent of the total material
emissions impact for new
home construction. Any
extrapolation of the total
impact of new home MCE
across the study region
should be done with
awareness of these
omissions.

14
 TERMINOLOGY
kg CO2e  Kilograms of carbon dioxide equivalent
t CO2e  Tonnes of carbon dioxide equivalent

Results & Discussion

The results from the EMBARC study provide insights at the level
of the entire housing sector in the region, individual houses,
material categories and specific materials.

3.1 Material Carbon Emissions (MCE)

and Material Carbon Intensity (MCI)
Each set of plans entered into BEAM was assessed for its net material carbon emissions
(MCE), the total of all material emissions minus any biogenic carbon storage. Table 4
summarizes the overall measured MCE results.

Table 4. Net MCE results for all measured materials

Net Material Carbon Emissions for 503 GTHA Sample Buildings

MCE MCE
Statistic Type
[kg CO2e] [t CO2e]

Best / Lowest Home Result 9,517 9.5

Worst / Highest Home Result 827,117 827.1

Mean (Average) 56,163 56.2

Standard Deviation 104,188 104.2

Weighted Avg by Qty Built 40,006 40.0

Median 39,350 39.3

Total of individual sample homes (59) 3,313,557 3,314

Total of sample 20,121,858 20,122

homes built (503)

Across the study’s sample of 503 as-built housing units, an estimated 20,122 t CO2e
was emitted, giving a weighted average of 40 t CO2e per unit. Extrapolating the study’s
average values to the 16,428 Part 9 homes typically built annually in the GTHA, and
adjusting for the average archetypal floor areas for each region, the total annual MCE
from new Part 9 homes may be roughly around 840,000 t CO2e annually.

This is the equivalent of the annual emissions from

more than 183,000 automobiles.23

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 15
 325
300

Material Carbon Intens

263 244
236 235 223
224
200 191
185 187
173

[kg CO2e / m2]

159 152
149 153
116 130
In comparison to other emissions sources
100 in the region, 104 this figure is slightly higher than
GHGs from residential waste (724,337 t CO2e) and well above agriculture (422,186 t CO2e).
Material carbon emissions assessed for
0 these three archetypes of homes in the GTHA
represents approximately 1.5 percent of total carbon
Total emissions inHeated
Floor Area the region
Area in 2020Habitable
24
. Area
Unit Area Type (MCI Denominator)
As discussed in Section 2.3, the MCE measured in this study may represent as little as
50 percent of the total MCE for these building typologies, due to the exclusion of MEP
equipment, appliances, finishes and millwork, suggesting a possible impact of 1.75 Mt
(megatonnes) of embodied carbon emissions from new GTHA Part 9 residential building
construction annually.

MCE by House Typology

100

Max
LEGEND:

90.7 90.7
90
80th Percentile
Mean
Median
20th Percentile
80
Min 77.7

70 69

66.6
Net Material Carbon Emissions

60 61.5
60

56.1
53.9
50
42.9

42.8
40 41.1
39.2 39.4 39.3
[tonnes CO2e]

35.1 37.2 35.4

30 31.6
28.9
29.9

20
18.5

10 9.5 9.5

0
Semi-detached Single Detached Townhouse All Typologies
House Typology

Figure 6. Total emissions are lowest for townhouses and highest for single detached,
largely due to differences in size. For all typologies, the median for the 503 homes was
MCI by House Type
39.3 tonnes of CO2e.

By Total Floor Area By Heated Area By Gross Floor Area By Habitable Area
Max
LEGEND:

800
80th Percentile
Mean
Median
20th Percentile
700
Min

600

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 16
500
 3,314 t CO e 2

59 house plans
40 t CO e 2

A single house avg.

59
S A M P LE
HOUSE
P LA N S

20,122 t CO e 2

503 as built homes

TOTAL
Material Carbon Missing building types for
Emissions
a complete emissions inventory

This study examines only new residential

buildings that meet the requirements of Part
9 of the Ontario Building Code, representing
only 44 percent of residential units constructed
= annually in the GTHA. Part 3 (large) apartment
183,000 and condominium units are built in greater
Annual Automobile
Emissions quantities and are not captured in this study.
840,000 t CO2e A more complete assessment of overall
GTHA extrapolation residential-sector MCE in the GTHA region
for materials included in the study would also need to consider the impacts of
renovation materials for existing buildings.
A complete assessment of all building MCE
emissions of the GTHA would need to include
all non-residential buildings as well. A study
from The City of Toronto, The University of
Toronto and Mantle Developments25 assesses
CITY SCALE = 380,000
MCE of some types of Part 3 (large) buildings
Annual Emissions
Annual Automobile in the region. The average A1-A3 emissions for
Emissions 38 buildings in the study was 345 kg CO2e/
m2, significantly higher than for the low-rise
1,750,000 t CO e 2 buildings studied in EMBARC.
GTHA extrapolation including
materials not calculated in this study

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 17
 TERMINOLOGY
MCE  Material Carbon Emissions

MCI  Material Carbon Intensity

Size matters
In the study, the smallest floor area belonged to a townhouse unit
of just 48 m2 (517 ft2) and the highest to a single family home of
1,475 m2 (15,880 ft2), a 31-fold increase in floor area. As might be
expected, such variation in home size has a direct influence on total
MCE.

Table 5 shows results by housing typology (isolating an exceptionally

large single family home outlier from the rest) and demonstrates the
influence of home size on MCE. The floor area reported in this table
is heated (also known as ‘conditioned’) floor area, which excludes
garage areas.
Table 5. Home size and average MCE.

Home size and average MCE and MCI

Number of sample Average MCE, Average heated Average MCI,

Housing typology
plan sets kg CO2e floor area, m2 kg Co2

Single detached 18 69,010 411 172

Semi-detached 5 39,209 241 173
Townhouse unit 35 29,951 166 193
Large single
1 827,117 1,475 561
family home

The MCE averages tend to vary proportionally with the size of the
units. Excluding the large single family dwelling, the average size of
a semi-detached home and a townhouse were 41 and 60 percent
smaller than the average single detached, respectively. Their MCE
averages were 43 and 57 percent lower than the average single
family home, demonstrating a correlation between size and MCE.

MCE is a useful metric for assessing the total GHG impact of any
particular house and of housing in the region. In order to recognize
the clear relationship between home size and emissions Material
Carbon Intensity (MCI) can be used. MCI is the result of total building
MCE divided by floor area (in square meters). MCI allows a relative
comparison of large homes to small homes and can be used to
project how material changes might affect homes regardless of
their size.

In this study, MCI was calculated using total building floor area,
heated floor area (excludes garage) and habitable floor area
(excludes garages and unfinished basements). Table 5 summarizes
the MCI results.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 18
 MCI by Floor Areas
Max 800
LEGEND:

80th Percentile 726

Mean
Median 700
20th Percentile

Min 600
561 560

500
454
400
373
329
Material Carbon Intensity

325
300
263 244
236 235 223
224
200 191
185 187
173
[kg CO2e / m2]

159 152
149 153
130 116
100 104

0
Total Floor Area Heated Area Habitable Area
Unit Area Type (MCI Denominator)

Figure 7. Material carbon intensity varies depending on the

defination of floor area being used.

Total floor area MCI for the weighted average of the 503 homes is 159 kg CO2e/m2, which is 17 percent lower
than MCI for heated floor area and 32 percent lower than habitable floor area (Figure 7). This points to the
importance of identifying the metric used to calculate MCI when comparing results. The need for industry and
MCE by House Typology
regulators to agree on appropriate metrics for MCI is addressed in Section 6.3.

100

Max
90.7 90.7
90
80th Percentile
Mean
Median
20th Percentile BEST AVERAGE WORST
80
Min Best, average and worst 116 77.7 191 561
MCI for Heated Floor Area kg CO2e/m2
MCI
kg CO2e/m2
MCI
kg CO2e/m2
MCI
70 69

66.6
n Emissions

60 61.5
60

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials
56.1 Benchmark Assessment for Residential Construction 19
53.9
50
42.9
 3.1.1 Housing Typology and MCI
Examining the MCI results by housing typology and by different definitions of floor area
highlight how important the selection of metrics for MCI can be. Depending on the metric
chosen, different typologies can be seen as best or worst.

Examined by total floor area, the difference in results for each typology are minimal, with
semi-detached the lowest MCI at 144 kg CO2e/m2 and single detached and townhouses
5 and 8 percent higher.
Table 6. MCI can be considered by floor area designation and/or house typology. Defining
these parameters will be important for policy makers.

Material Carbon Intensity (MCI)

[kgCO2e/m2] (weighted average)
Single Semi-
Area Type Townhouse All Types
Detached detached
Total floor area 152 144 156 154
Heated floor area 167 156 199 189
Municipally defined gross floor area 209 216 185 193
Habitable floor area 229 213 224 225

Examined by heated floor area the differences get The study of material carbon emissions is relatively
larger. The weighted average for semi-detached new. The intent of this study is to help inform potential
homes in this study had the lowest MCI, at 156 kg policy action to incentivize or regulate these emissions
CO2e/m2, with single detached homes 7 percent in the home building sector. Effective policy will
higher and townhouses 22 percent higher. require appropriate metrics to ensure that policies
do not create perverse incentives or negatively
Using a definition of gross floor area employed by impact other policy priorities. As the results of this
some municipalities in the GTHA (which counts garage study demonstrate, changing the unit upon which
area but ignores basement area), the townhouse emissions intensity is measured can dramatically alter
becomes the best result at 185 kg CO2e/m2, with the results. For example, calculating MCI by total
single detached 11 percent higher and semi-detached floor area compared to heated or habitable floor
14 percent higher. area can change the MCI result by 19 and 32 percent,
Using only habitable floor area as the basis for MCI respectively.
semi-detached homes have the lowest result, 5 and 7 Priorities such as increasing residential density,
percent lower than townhouses and single detached, reducing uninhabited space or emission reductions
respectively. through renewable energy systems could be
Clearly, the choice of metrics for measuring MCI can incorporated into a new metric. The researchers
have an important impact on the results for different explored Material Carbon Intensity by Function, or
types of homes. As discussed in Section 6.3, policy MCIF (see Sidebar XX) as an example of a metric that
makers must weigh the impacts of the metrics they can combine desired outcomes.
select carefully to ensure they support other municipal
priorities such as density.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 20
 3.1.2 Combining Material and
Operational Emissions: Carbon Use Intensity
The EMBARC study did not include the operational would allow regulators to compare the combined
carbon emissions (OCE) of the homes in the study. operational and material emissions associated with a
However, consideration of both MCE and OCE is new home to their broader climate mitigation targets.
critical to understanding a more complete scenario of
emissions arising from new homes. The NRCan report Achieving Real Net Zero Emission
Homes discusses the importance of considering CUI:
Carbon Use Intensity (CUI) is a metric that adds a “The effort to shift to a CUI metric could, despite the
home’s operational carbon emissions (OCE) to its challenges, put the sector on the proper footing to
MCE to demonstrate the total impacts of both these meet the country’s 2050 climate goals in a way that is
significant factors. Since OCE accumulates annually, more holistic and offers more flexibility to the unique
the CUI metric is usually associated with a particular conditions that exist in every region where homes
time period. CUI can be expressed according to a are built.”26 The “flexibility” refers to the options left
number of years (ie. CUI30 would be the total of MCE to builders to weigh the impacts of energy efficiency
and OCE over a 30 year period) or according to a measures, fuel choices and material selection to best
fixed time window (ie. CUI2030 would be the total meet the needs of their homeowners while adhering
of MCE and OCE between the date of construction to the climate goals of the country, province and/or
and the year 2030). Either version of the CUI metric municipality.

Operational Carbon
Emissions

Material Carbon
Emissions
(MCE) ENERGY

+ = CUI
USE INTENSITY
+

ENERGY
SOURCE EMISSIONS

EXTRACTION + TRANSPORTATION + MANUFACTURING

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 21
 Figure 8 shows the CUI30 results from the NRCan Consideration of MCE as an important factor in
study for a model two-storey home in Toronto and overall emissions from the homebuilding sector is
demonstrates how the variables of energy efficiency, very recent. The selection of a metric for calculating
fuel choice and MCE can impact overall emissions and reporting MCE will have an important impact on
over a 30 year period. By working with a CUI metric, how MCE is addressed and potentially regulated and
the builder could determine the best path to meeting should be an important part of ongoing discussions.
a CUI target.

CUI for Toronto 2-storey home scenarios

CARBON USE
BUILDING OCE INTENSITY
SPECIFICATIONS MCE (FOR 30 YEARS)

Moderate
Emissions Materials 42.6 t
Code Compliant, CUI30
Electric Heat Pump
28.4 t MCE 14.2 t OCE

Moderate
Emissions Materials 40 t
Net Zero Ready, CUI30
Electric Heat Pump

31.2 t MCE 8.8 t OCE

Moderate
Emissions Materials 100.1 t
Net Zero Ready,
Gas Heat
CUI30
30.5 t MCE 69.6 t OCE

Best Available
Materials 13 t
Net Zero Ready,
Electric Heat Pump
CUI30

4.2 t MCE 8.8 t OCE

Figure 8. Carbon Use Intensity for the same home design is impacted by both MCE and OCE.
Energy efficiency, fuel type and material selections all have an impact on CUI.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 22
 Exploring new by floor area as is typical, to encourage the
metrics for MCE: optimal use of constructed space. As this ratio
decreases from one, the MCIF increases. For
Four performance criteria were chosen by example, if half of the floor area is unfinished
Erik Bowden, one of the study’s authors, to basement and garage space, the MCIF is
be addressed by a new MCI metric, which doubled. In cases where all floor area is
aims to have positive carbon and housing habitable (i.e. a 1:1 ratio), there is no impact on
availability impacts for regions that adopt it. the metric.
These include increasing housing occupancy
To address housing needs in combination
capacity, using the number of bedrooms as a
with material carbon, it is proposed that the
proxy for occupancy, decreasing uninhabited
number of bedrooms per housing unit be
included in the MCIF metric as a proxy to
CA occupancy capacity. All other factors being
MCIF = equal, a home with more bedrooms will have
B Ah a proportionally lower MCIF value.
C = net MCE in t CO2e,
Unifying these four factors into MCIF is
B = quantity of bedrooms in the unit
A = gross area in m2, and Ah = habitable area in m2. just one suggested method among many
emerging ways of evaluating a home’s
space, decreasing gross building size relative emissions intensity. One downside of MCIF
to occupancy, and decreasing the building’s could be that with simplification, resolution
overall MCE. of the contributing factors is lost. Though
slightly more complex, it may prove to be
Using these factors, Bowden proposes
better to use multiple separate metrics in
a derived metric called Material Carbon
coordination in order to maintain resolution,
Intensity by Function, or MCIF, with the units of
such as total MCE, MCI/bedroom and MCE/
t CO2e/bedroom.
m2 of habitable floor space, each with their
The lower the value obtained, the better own benchmarks and bounds. Ultimately,
the building is at achieving the performance as long as these separate metrics are used
criteria, overall. concurrently to focus evaluation on the
desired goals, deleterious effects caused by
A ratio of gross floor area to habitable floor
any one metric should be constrained by
area was applied, rather than only dividing
the others.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 23
 3.2 Material Analysis
All new homes are amalgamations of many different home, such as concrete (in slabs, basement walls,
materials. The BEAM models for each home in this garage floors, and footings.) and insulation (in floors,
study provide insights about material use that can walls and roofs). Figure 9 shows the total emissions
be helpful at different levels: comparison of broad attributed to each of the main materials categories in
material categories, comparison within material all 503 sample homes.
categories, and materials with high per-use emissions
or carbon storage. Each level can help focus Concrete, insulation, and cladding are the three
regulatory, design and procurement attention where most emission-intensive categories of Part 9 home
impacts can be greatest. building material, together representing 72 percent
of the measured MCE. Serious emission reductions in
these three categories would be the most impactful
Material Categories
interventions, and each is explored in more
Material categories capture the impacts of materials detail below.
that may show up in more than one assembly in a

INSULATION CONCRETE
72
of total MCE
%
5,242,864 kg CO2e 6,647,924 kg CO2e from just three

26.1 %
Includes walls, roofs, 33%
material categories!

floors and foundations Includes footings,

foundation walls & floor slabs

CLADDING INTERIOR
2,575,309 kg CO2e SURFACES
2,166,831 kg CO2e

12.8 %
10.8%
Includes flooring,
WINDOWS
1,385,851 kg CO2e
walls & ceilings
6.9%
ROOFING
447,537 kg CO2e
Figure 9. Total emissions from 503
homes by material category. STRUCTURAL FRAMING 2.2%
POSTS AND BEAMS 633,257 kg CO2e
1,022,555 kg CO2e
3.1%
5.1 %

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 24
 3.2.1 Concrete
Concrete plays an important role in new homes, For determining the carbon emissions of concrete,
as it is the dominant material choice for footings, the BEAM tool uses an Environmental Product
foundation walls and floor slabs. Every home in Declaration prepared by the Canadian Ready Mix
the study used concrete for these elements. The Concrete Association28 which presents industry-wide
pervasiveness of the material along with its relatively average data. For concrete in the 0-25 MPa (~3,000
high MCE means that the concrete components psi) compressive strength category (typical for use in
of GTHA homes had the largest impact on overall Part 9 homes), this EPD presents 19 different possible
emissions, representing 33 percent of total emissions mix designs, each with different GWPs that range
from new homes. Figure 10 shows the contribution of from a high of 327 to a low of 214 kg CO2e/m3. This
concrete, rebar and reinforcing mesh to this total. EPD declares an “Industry Average Benchmark” of
305 kg CO2e/m3 and this is the figure selected in
The impact of concrete emissions is sizable as BEAM for all concrete calculations in this study.
calculated, but may be understated (or, less likely,
overstated) due to a lack of product-specific data
about concrete mixes in the building plans and from
GTHA regional plants.27

INSULATION CONCRETE
26.3 %
32.9%

CONCRETE
CLADDING INTERIOR
5,967,177 kg CO2e
SURFACES
13.3 %
10.1% FRAMING
6.8%
WINDOWS

5.1% 89.8%
ROOFING
2.2%

Figure 10. Concrete emissions by

component material.

WIRE MESH
86,354 kg CO2e

1.3% REBAR
588,830 kg CO2e

8.9%

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 25
 The EC3 (Embodied Carbon in Construction Calculator) tool29 is the largest repository of
construction material EPDs in North America, and while it contains 109 product-specific EPDs for
0-25 MPa (28 day compressive strength) concrete from Canadian manufacturers, none of these
originate from Ontario. More broadly, the lowest GWP for Canadian concrete in EC3 is 93 and the
highest is 828 kg CO2e/m3. EC3 calculated an average of 390 kg CO2e/m3 for Canadian concrete
calculated using uncertainty factors arising from the quality of data used in generating EPDs. Table
7 shows the impact on overall concrete emissions in this study by applying different GWP factors
for 0-25 MPa concrete.
Table 7. Comparison of possible GWP factors for 25 MPa concrete in Canada
*Total GWP for concrete only, does not include rebar or mesh

GWP Emissions from 503

Concrete Mix Factor samples, Percentage
kg CO2e/m3 kg CO2e change from
CRMCA - 0-25 MPa, benchmark
305 4,269,344*
Canadian Benchmark Avg.

Butler Concrete N254 124 1,738,469 -59%

LaFarge ECOPact RMXUG35A3A8M 170 2,383,385 -44%

CRMCA Mix #19 - 0-25 MPa, 35-50% Slag, GUL 214 3,000,260 -30%

CRMCA Mix #18 - 0-25 MPa, 35-50% Slag, GU 234 3,280,660 -23%

CRMCA Mix #10 - 0-25 MPa, 30-40% Fly Ash, GU 250 3,50,478 -18%

CRMCA Mix #12 - 0-25 MPa, 25-34% Slag, GU 268 3,757,337 -12%

CRMCA Mix #6 - 0-25 MPa, 15-29% Fly Ash, GU 283 3,967,635 -7%

CRMCA Mix #1 - 0-25 MPa, 0-14% FA/SL, GU 327 4,584,512 +7%

EC3 Avg. for 107 Canadian 25 MPa concrete EPDs 390 5,467,766 +28%

EC3 Conservative estimate for Canadian 25 MPa 507 7,108,096 +66%

LaFarge ​​RMXK925A21F 610 8,552,147 +100%

Concrete mix design can have a large impact on GWP factors. The use of supplementary
cementitious materials (SCMs), including fly ash and blast furnace slag, account for 25
percent of the difference between results in the CRMCA EPD (it is important to note that
availability of fly ash and slag quantities will diminish as the emissions-intensive industries
that produce these byproducts are scaled down over the next decades). Use of Type 1L/GUL
(Portland-Limestone) Cement offers a 5-15 percent reduction in GWP, and in combination
with high percentages of SCMs can bring overall emission reductions of up to 35 percent, as
seen with Mix #19.

If the EC3 average of 390 kg CO2e/m3 is applied to all 0-25 MPa concrete in this study,
overall emissions would increase from the 4,269 t CO2e assumed in the study to 5,468 t
CO2e, a 28 percent increase.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 26
 Today’s best available concrete
could eliminate 2,500 tons of
emissions from new home
construction annually.

At worst, 0-25 MPa concrete with a high GWP factor as treated wood foundations. Homes built above-
of 610 kg CO2e/m3 (as would be the case with five grade using pier or pin foundations can eliminate
Canadian EPDs found in the EC3 database) would concrete use altogether. It is beyond the scope of
raise concrete emissions in this study to 8,552 t CO2e, this study to directly analyze the minimization or
a 100 percent increase. If GTHA builders were able to elimination of concrete, but while concrete is the
access the best-possible 0-25 MPa Canadian concrete largest contributor to MCEs these options may be
mix, emissions would be reduced by 2,531 t, a 59 worth further exploration.
percent reduction.
Changes in concrete mixture formulation has
The wide range of results arising from different implications beyond emissions. Mixes with high
concrete GWP factors points to the importance of proportions of SCMs can take longer to cure and
obtaining reliable, manufacturer-specific EPD data for therefore impact construction schedules. While it is
concrete for GTHA homes. Without such data, taking beyond the scope of this report to explore this issue,
quantifiable action on the largest source of emissions it certainly requires consideration.
from new home construction will be difficult.
The concrete industry may see innovations that
The BEAM tool enables users to input “User Defined will change the GHG-intensity of their products.
Options” and this would enable information from CO2 injection has been shown to reduce GWP by
any valid concrete EPD from a local supplier to be 4-6 percent30 (on top of reductions available via
calculated in a model. The use of product specific cement substitution noted above) and is available
EPDs in the concrete category is an essential step in on the market now. The use of captured CO2 to
properly assessing the emissions and reductions in make aggregate could result in concrete that stores
this critical category. more carbon than it emits.31 The use of biochar as an
aggregate can similarly reduce the MCE of concrete.
While mix design offers opportunities for emissions Policy makers and builders will want to keep up with
reductions, it is possible for new homes to be developments in this field as they could dramatically
designed to use less concrete by minimizing below- remake the emissions map for new homes.
grade construction and/or substituting materials such

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 27
 3.2.2 Insulation the average results for each type of insulation at the
Insulation accounted for 5,242 tonnes of emissions in same level of thermal performance. While direct
the study, representing 26.1 percent of all measured substitutions between products in Figure 11 cannot be
MCE. As the second highest impact category, simply assumed, due to differences in performance
addressing emissions from insulation is clearly characteristics, there is an order of magnitude of
important. difference between the emissions of the options. It
is important to note that within a particular material
A leading strategy for reducing MCE in homes is to type, the carbon emissions for specific products made
design to use less material. But with increasing (and can vary by over 50 percent (see Figure 11).
important) demands for improvements in home
energy efficiency to reduce operational emissions, In some cases, a product with low emissions in
new homes will likely be using more insulation, not its category may have a lower R-value per inch of
less. So as we push to improve energy performance thickness than another product with high emissions
we risk driving the significant MCE from insulation in its category, meaning a greater quantity of the
ever higher. product must be used to achieve an equivalent
R-value. For net carbon emitting insulations, this
The MCE of insulation products varies widely. There generates higher emissions. Conversely, for net
are 20 different insulation types in BEAM, many with carbon-storing insulations, this achieves greater
multiple product brands or options. Figure 11 shows carbon storage.

Insulation Emissions Comparison for 100 m2 @ R5

XPS Foam Board R 5/inch 4937
Aerogel Batt R 9.6/inch 1652
Closed Cell Spray Foam (HFC) R 6.6/inch 1159
NGX Foam Board R 5/inch 715
Vacuum Insulated Panel R 30/inch 654
Mineral Wool Board R 4.2/inch 473
Closed Cell Spray Foam (HFO) R 6.6/inch 366
EPS Foam Board (Type II) R 4/inch 288
Polyisocyanurate Foam Board R 6.5/inch 252
Open Cell Spray Foam R 4.1/inch 146
Mineral Wool Batt R 4/inch 115
Wool Batt R 4/inch 114
Fiberglass Blown In R 2.6/inch 88
Fiberglass Batt R 3.6/inch 59
Hemp Fiber Batt R 3.7/inch -70
Cellulose R 3.7/inch -202
Wood Fiber Batt R 3.9/inch -218 Each result is an
Hempcrete R 2.1/inch -554 AVERAGE of a range
Wood Fiber Board R 3.4/inch -663 and products can vary
by as much as 50%
Straw Bale R 2.8/inch -753

kg CO2e -2000 0 2000 4000 6000

Figure 11. Range of net emissions for different insulation types from BEAM software.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 28
 Complicating the substitution of insulation materials 3.2.2.1 Carbon-storing Insulation
is the different performance characteristics required Of the insulations used in the buildings of this study,
of insulation products in different assemblies of the only two carbon-storing materials (cellulose and wood
home. Foundation wall insulation is responsible for fiberboard) were used, which together stored just under
the majority of all insulation-related MCE, mostly 400 tonnes of plant-sequestered CO2e emissions. The
due to the exterior application of rigid XPS foam. carbon storage of these two materials reduced the
One possible solution for reducing foundation wall overall insulation category impact by 7.0 percent, while
carbon emissions is to substitute exterior subgrade only contributing 2.0 percent to insulation emissions.
insulation with appropriate interior blanket or batt These materials are composed primarily of biologically-
insulation with a lower carbon footprint. All insulation produced matter, sometimes termed biogenic
substitutions must be made using the best available material. The carbon storage these materials claim was
building science principles. sequestered from the atmosphere by photosynthesis
Figure 12 shows the total impacts of different and made into physical carbon-based matter during the
insulation types, regardless of their position in the plant’s growth. (see Section 2.3.2).
building. There are different demands on insulation
products depending on their location in building Due to the high volume of insulation used in homes
assemblies, and some types of insulation may be used (and the likelihood of increases in insulation volume
successfully in multiple locations in the building while to meet new energy efficiency requirements), the
others may be limited to just one or two types of uses. use of more carbon-storing insulation offers the
most potential to dramatically reduce overall MCE.
The potential results of using more carbon-storing
insulation are explored in Section 4.

INSULATION CONCRETE Figure 12. Proportion of

insulation emissions by
26.3% 32.9 %
product type.

XPS FOAM
BOARD*
CLADDING INTERIOR
SURFACES
13.3% 10.1% FRAMING WINDOWS

5.1%
FIBERGLASS
6.8%
4,581,864 kg CO2e BATT
ROOFING
2.2%
346,709

87%
kg CO2e
7%
MINERAL
WOOL
BOARD SPRAY
*This figure is for “legacy 274,740 kg POLYURETHANE
formula” XPS insulation. CO2e
FOAM
As of 2021, federal law 5% 199,888 kg CO2e
requires a lower GWP 4%
formulation which can
substantially reduce Wood fiber board
-7,091 kg CO2e SPRAY
this figure.
POLYURETHANE
> -1% OTHER
FOAM - OPEN CELL
59,810 kg CO2e
Cellulose loose fill 68,999 kg CO2e
-271,646 kg CO2e >1%
1%
-5 %

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 29
 3.2.3 Cladding
The cladding category had the third highest emissions
impact, with 2,575 t CO2e representing 12.8 percent
of the total MCE in the study. Figure 13 shows the
relative emissions for the cladding options included in
the BEAM tool.

Cladding is a relatively straightforward material

category, with each option available in the BEAM
tool having met all testing requirements for the
purpose and most having long histories of use in the
region, which should make direct substitutions a
viable option. However, cladding is a material with
a high aesthetic impact for a home – as well as major
differences in durability and maintenance – and
substitutions on the basis of emissions alone may
not overcome decisions based on the desired visual
appearance of the home.

Cladding Emissions, kg CO2e/100m2

Brick 4725
Acrylic Stucco 3500
Aluminum Panel - 22 gauge 1953
Fiber Cement - 5/15” 1703
Steel Panel - 24 gauge 1496
Lime Plaster (NHL) - 3/4” 957
Vinyl - 0.040” 538
Polypropylene - 0.085” 487
Lime/Cork Plaster - 3/4” 356
Engineered Wood - 5/16” 278
Wood (Cedar) - 3/4” 172
Wood (SPF) - 3/4” 120
Clay Plaster - 9/16” 88

kg CO2e/100m2 0 1000 2000 3000 4000 5000

Figure 13. BEAM results for cladding

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 30
 There are not currently any commercially available The testing of bricks using biochar as a high volume
cladding options with significant net carbon storage, ingredient has demonstrated net carbon storage that
though some wood products may eventually have would equate to -1,778 kg CO2e/100 m2 in a cement/
carbon storage attributed to them (see Section 2.3.2). biochar brick of typical thickness.33 This is an average
However, even without carbon-storing options, it is reduction of 138 percent from the MCE of bricks
possible to reduce emissions by orders of magnitude. used in this study’s sample buildings. If this biochar
brick were hypothetically substituted for all brick
The GTHA region features brick as a common cladding in the sample homes, it would result in the
cladding material. All of the GTHA representative net carbon storage (i.e. negative emissions) of 500
home plans sampled included brick cladding, except tonnes of CO2e, approximately one tonne per home
for one. Brick is by far one of the most emission- on average.
intensive cladding options, with the bulk of the
embodied carbon emissions arising either from the Until such low-carbon or carbon-storing brick
kiln-firing of clay bricks or the cement content of replacements become available, a move to any other
concrete bricks. cladding choice that is under 1000 kg CO2e/100
m2 would reduce emissions by at least 75 percent
While no low-emission brick products are currently in this category. This includes using siding made
available in the GTHA, it is worth noting that US of vinyl, polypropylene, wood, and engineered
manufacturer CalStar Brick issued an EPD for their fly- wood, and/or non-cement based plasters such as
ash brick product that would have 472 kg CO2e/100 lime and clay plaster. After biochar bricks, the lowest
m2, or one tenth of the emissions of typical bricks. If emission cladding option is clay plaster at a mere 88
this brick substitution were made in all the buildings kg CO2e/100 m2. Clay plaster has 98 percent lower
in this study, it would eliminate 1,200 t CO2e of carbon emission than the industry average brick
embodied carbon32, the same carbon reduction as emission of 4,725 CO2e/100 m2.
achieved by switching all 0-25 MPa concrete to the
lowest carbon mix available, as discussed in Section
Figure 14. Carbon emissions of cladding by type for
3.2.1 . all 503 as-built homes studied.

INSULATION CONCRETE
26.3% 32.9%

BRICK
CLADDING
13.3%
INTERIOR
SURFACES
10.1%
2,504,725 kg CO2e
FRAMING WINDOWS

98.1%
6.8% 5.1%

ROOFING
Vinyl Siding 0.9%
2.2% Fiber Cement Siding 0.5%
Metal Panel Siding 0.5%
Wood Siding 0.1%

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 31
 4. Effects of Material
Substitutions on MCI 4.1a Best available materials
(BAM) substitutions
The results of this study indicate that material selections for new Substituted materials were chosen to
home construction can have a dramatic impact on material carbon ensure that they are readily available
emissions. To explore the potential extent of MCI reductions based in the GTHA marketplace and meet
on material selection, the researchers applied material substitutions all current code requirements. Two
in the BEAM models in areas where material impacts were shown to kinds of substitutions were made in this
be highest. model: switches to new material type
The homes with the lowest and highest34 MCI results were selected and switches to best-in-type materials
for material substitutions to examine whether any reductions might (ie. brand-specific change). These
relate to the overall design of the building or the as-built material substitutions were chosen to reflect as
selections. Two new BEAM models were created for both samples. much similarity in product application
The first scenario focuses on materials that could feasibly be selected as possible (ie. if batt insulation was
by builders today to explore how low MCI could go in the immediate selected for the as-built model, another
future, while the second scenario is intended to demonstrate the batt insulation was chosen to substitute)
possibilities for MCI reduction in the next 5-10 years. to ensure that substitutions would be
practical for real-world applications.

In the BAM model, major substitutions include:

✔ Concrete selection was changed from the Canadian benchmark

average of 305 kg CO2e/m3 to the lowest emitting mix from the
Canadian average EPD (Mix #19 at 214 kg CO2e/m3), as this type of
mix should be available from regional suppliers.

✔ Insulation was changed to cellulose batts (for walls) and loose-blown

cellulose (for attics).

✔ Cladding was changed from brick to the lowest emitting low-

maintenance option, engineered wood.

Minor substitutions include:

✔ Carpet flooring changed to best available option

✔ Hardwood flooring changed to linoleum

✔ Drywall changed to best available brand

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 32
 4.1b Best possible materials (BPM) substitutions
Materials were chosen to reflect the best possible emission results, regardless of whether or not the materials
are market-ready. All materials are commercially available in other markets, and have demonstrated code
compliance in those jurisdictions. Though this does not guarantee that such materials can be substituted in the
GTHA currently, it indicates a likelihood that this should be possible with adequate testing. Such substitutions
may require design changes and worker retraining for installation.

In the BPM model, major substitutions include:

✔ Concrete selection was changed from the Canadian benchmark

average of 305 kg CO2e/m3 to 150 kg CO2/m3, an average of the two
best product-specific EPD results in Canada. While not necessarily
widely available, this type of mix requires no new technology and
should be able to be produced in the region.

✔ Insulation was changed to straw-based material, based

on baled straw wall insulation and loose-blown chopped
straw insulation available in Europe.35

✔ Interior walls were changed to compressed straw board,

based on modular interior partition systems available in
Europe and Australia.36

✔ Cladding was changed from brick to

the lowest emitting low-maintenance
option, engineered wood.

Some of these substitutions would

require new products to become
✔ Windows changed from vinyl
frame to wood frame with available in the regional market
aluminum cladding and some efforts to both redesign
aspects of the home and retrain
crews to install new materials.
However, the existence of homes in
✔ Interior drywall was changed to
Europe and some examples here in
sheets of compressed recycled
drinking boxes, based on products Canada38 using all of these materials
available in the USA and Europe.37 indicates the potential, and one with
significant emission implications, as it
changes new homes from a source of
emissions to a source of net
✔ Flooring was changed to a mix of carbon storage.
linoleum (for high-wear and wet
areas) and cork.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 33
 4.2 Results of material substitutions
The home with the lowest MCI in this study had an emissions Possible
NOW
intensity of 116 kg CO2e/m based on heated floor area. This %
51
2
Possible
result puts this home well under the weighted average of SOON
189 kg CO2e/m2, for the same heated floor area critera. If
all new Part 9 GTHA homes matched the MCI achieved
REDUCTION
in carbon emissions 147%
REDUCTION
by this as-built home, it could reduce the total carbon in carbon emissions

emissions by as much as 465,850 tonnes, roughly a 55

percent reduction from the current estimated emissions. This
in itself would be a remarkable impact, equivalent to removing
approximately 100,000 cars from the road. It is worth noting that
this example was a typical townhouse unit from a large developer
that presumably did not intend to achieve a low MCI score when it
was designed or built. An MCI of 116 kg CO2e/m2 could therefore be
considered an easily achievable minimum target for conventional and
cost-competitive buildings.

Table 8 shows the results of the six BAM and seven BPM substitutions for
the model with the lowest MCI based on heated floor area.

NET CARBON EMISSIONS Original model – BAM BPM

by assembly [kg CO2e] Lowest MCI Substitutions Substitutions

FOOTINGS & SLABS 4,002 2,718 1,677

FOUNDATION WALLS 11,825 7,971 1,335
STRUCTURAL ELEMENTS 808 808 808
EXTERIOR WALLS 514 -397 -3,221
PARTY WALLS 818 166 -1,204
EXTERIOR WALL CLADDING 2,077 235 122
WINDOWS 1,285 1,285 800
INTERIOR WALLS 965 908 -6,357
FLOORS 3,250 1,593 838
CEILINGS 268 251 -1,061
ROOF 2,742 -242 -7,947
GARAGE 4,485 823 -1,361
NET TOTAL MCE 33,039 16,120 -15,571
NET MCI OF HEATED AREA (kg CO2e/m2) 115.8 56.5 -54.6
% CHANGE FROM INITIAL -51% -147%

Table 8. Comparison of results for material substitutions for lowest MCI home (based on heated floor area).
The six BAM substitutions result in a reduction of MCI to 56.5 kg CO2e/m2, a 51 percent reduction from
as-built emissions. The substitution of seven Best Possible Materials (BPM) provides an encouraging result:
a home with net carbon storage in the measured materials, rather than emissions. The result of -54.6 kg
CO2/m2 is a 147 percent reduction from the as-built model.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 34
 A home with high MCl was given the same set of material substitutions as the low MCI model.
The results in Table 9 show that despite the higher initial MCI of 262.1 kg CO2e/m2, the BAM
substitutions actually reduced this model’s emissions by 196.6 kg CO2e/m2, a 75 percent
reduction. Possible
NOW
NET CARBON EMISSIONS
[kg CO2e] 51%Original model –
Highest MCI
Possible
BAM
Substitutions
SOON
BPM
Substitutions
REDUCTION
FOOTINGS & SLABS 5,793
in carbon emissions
4,648 147% 3,093
FOUNDATION WALLS 36,805 REDUCTION
7,805 2,030

✔
in carbon emissions
STRUCTURAL ELEMENTS 1,349 1,349 1,349
EXTERIOR WALLS 12,481 -2,265 -9,076
EXTERIOR WALL CLADDING Material Subsitution
10,756 1,105 806
WINDOWS 2,325 2,325 1,447 118%
=
INTERIOR WALLS 702 660 -4,653 REDUCTION
in carbon
FLOORS 4,572 2,346 1,296 emissions
CEILINGS 533 437 -1,358
ROOF 1,648 1,276 -7,904
GARAGE 4,546 694 -1,662
NET TOTAL MCE 81,510 20,380 -14,632
NET MCI OF HEATED AREA
(kg CO2e/m2)
262.1 65.5 -47.1
% CHANGE FROM INITIAL -75% -118%

Tabel 9. Material substitutions for second highest MCI home (based on heated floor area)

The BPM substitutions brought this home’s total across all new Part 9 homes in the GTHA region.
MCI to -47.1 kg CO2e/m2, a 118 percent reduction Reducing the weighted average MCI of 192.6
from the as-built result. This represents nearly 100 kg CO2e/m2 (based on municipal data floor area
tonnes of CO2e emissions eliminated from a 252 m2 criteria) to the average BAM-substitution MCI of 80.1
single family home as a result of only seven alternate kg CO2e/m2 (based on the same floor area criteria)
material choices. would result in approximately 573,000 t CO2e fewer
emissions annually in the GTHA. Achieving average
The similarity between the MCI results from BAM- BPM-substitution results of -67.3 kg CO2e/m2 (again,
substitution (56.5 and 65.5 kg CO2e/m2) and BPM- based on the municipal data floor area criteria)
substitution (-54.6 and -47.1 kg CO2e/m2) indicates would result in the reduction of roughly 1,065,000
that material selection can drastically reduce MCI, t CO2e. In this hypothetical scenario, new Part 9
regardless of home design, as the use of a similar homes built in the GTHA would pass beyond net
material palette results in similar MCI outcomes. zero carbon to store around 225,000 tonnes
The similarity between the material substitution of carbon from the atmosphere during a single
results invites the calculation of a hypothetical construction year.
estimate of the potential impact of such substitutions

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 35
 In the near future,
new Part 9 homes built in the
GTHA could pass beyond net
zero carbon to store around
225,000 tonnes of carbon from
the atmosphere during a single
construction year.

4.3 A carbon-storing future?

The BPM substitutions in this study had a dramatic impact
on MCE, completely reversing the impact of home
building materials measured in this study from a source of
emissions to a potential pool of net storage. As selected
for this study, the BPM category only included materials
for which commercially available options exist in other
markets. Carbon-storing materials that are currently in
R&D would offer even further potential for net storage. What does it cost
Should a concerted effort be made to encourage the use,
to reduce MCE?
distribution and development of carbon-storing materials –
including promising materials like carbon-storing concrete
Though it was outside the scope of this report
aggregate and biochar-based materials – it may be
possible to achieve even more net carbon storage than this to comment accurately on the cost implications
study indicates. of material substitutions, correspondence with
several regional concrete suppliers indicated
The home building sector may be unique in the potential
for a relatively rapid transformation from a major source of that a low-carbon concrete mix substitution
GHG emissions into a zero-carbon or even carbon-storing would not have any notable cost implications.
sector. Combining the best efforts underway to achieve Pricing from HomeAdvisor.com shows average
zero emissions in operations and the use of carbon-storing installed prices for brick are $9-28 per square
materials could result in the elimination of emissions from
foot, compared to $7-12 for engineered wood.
this sector.
Cellulose insulation priced from three major
4.4 No changes to home designs Canadian retailers was less expensive than the
as-built options, though installation costs may
This study did not examine the impact of design changes,
such as moving space currently below grade to become vary. On the whole it is encouraging that the
above grade (either fully or partially), massing changes, most impactful substitutions on emissions do
solar orientation, window sizing, air tightness or not appear to have significant negative cost
mechanical systems. Any or all of these types of design implications and could potentially cost less. This
changes could directly impact the MCE and OCE
factor would be valuable to study in more detail.
of the homes.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 36
 Conclusions
MCE is Substantial
The climate emergency has dire consequences for everyone in the GTHA and will require effective mitigation
and adaptation efforts on behalf of every citizen and sector of the economy. Recognition of the importance of
climate impacts has led to the study of material carbon emissions (MCE), and as this study demonstrates, these
impacts are substantial.

The structural and enclosure materials calculated for the built sample plans in this study represent over 20,100
tonnes of CO2e emissions annually. This would represent roughly 840,000 t CO2e per year if extrapolated to all
new Part 9 housing starts in the GTHA.

5.1 MCE is more substantial Part 9 commercial buildings may have higher MCE
than reported in this study than residential buildings, as they often feature large
While the materials included in this study represent concrete slab floors and enclosure systems that use
a large portion of MCE from new homes, the steel framing rather than wood, which has a much
excluded materials – such as mechanical, electrical higher MCE. Frequent renovations and interior
and plumbing systems, millwork, paints and upgrades to commercial buildings likewise represent
finishes – could add anywhere from 30-60 percent a potentially large pool of MCE.
more emissions to those calculated in this study. MCE from Part 3 (large) buildings exceed that of
That suggests that the total MCE for new homes in the Part 9 buildings studied here with an average
the GTHA could be as high as 1.2 -2.1 Mt CO2e of of approximately 345 kg CO2e/m2, due to the high
(potentially avoidable) emissions per year. volume use of impactful materials like concrete and
structural steel, and would likewise add to the total
5.2 MCE for Part 9 renovations and other MCE for the region.
building activities likely substantial
This study focuses on new homes that fall within Part 5.3 MCE analysis should become
9 of the Ontario Building Code. The importance and standard practice
scale of MCE would grow considerably if renovations The measurement of MCE for new homes should
to Part 9 buildings were included, especially in become standard practice in order to collect more
light of the proliferation of subsidy programs for accurate and complete data and help to drive
retrofitting older homes to be more energy efficient. voluntary emission reductions and inform future
The conclusions of this study regarding the high regulatory interventions. Tools such as BEAM (used
emissions impact from insulation materials are in this study) and Natural Resource Canada’s MCE2
perhaps even more relevant when it comes to retrofits are free and establish a common methodology for
where insulation is often the main material category estimating MCE particularly for Part 9 buildings, that
being added. It is quite likely that a study of retrofit are relatively simple for policy makers, consultants,
MCE compared to OCE reductions would find that, designers, and builders to use. Technical training for
as with new buildings, the addition of high emission MCE calculation could be supported by regulators
insulation materials may result in more total emissions and the industry to normalize the practice and
over the next few decades, rather than the net increase MCE literacy.
reductions that are intended by subsidies.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 37
 5.4 Carbon storing
materials are an important strategy
This study created updated versions of two model increase in the net carbon storage possible in a new
homes (one with the low MCI and one with high) home.
to examine the impact of material substitutions on
overall emissions. The substituted materials that offer Studying the cost implications of using more
net carbon storage (i.e. more atmospheric carbon carbon-storing materials was not within the scope
was stored in the materials than was emitted in of this report. An initial exploration (see Sidebar XX)
manufacturing; see Section 2.3.2) offset substantial indicated that costs would not necessarily be higher
amounts of emissions from the other materials. for the BAM models, offering the possibility that
Using the best available materials (BAM) in six deep cuts in MCE are possible with reasonable cost
categories, the carbon-storing materials reduced implications. Costs for the BPM models were difficult
MCI by 51 percent for the low MCI model and 75 to assess, as many of the material options are priced
percent for the high MCI model. Using “best possible for other markets and are not widely available in the
materials” (materials available in other markets but local region.
not necessarily code compliant or in wide use in The opportunity for new homes to be sites of net
the GTHA), the results were 147 and 118 percent carbon storage rather than emissions offers a feasible
reductions, bringing the homes into net carbon pathway for achieving the net zero emission targets
storage territory. promised by national and regional governments.
The “best possible materials” models do not include The development and promotion of existing and
carbon-storing material options that are currently in upcoming carbon-storing materials would be a crucial
development, such as concrete aggregate made from factor in reaching net zero emissions in the home
captured carbon and bricks made with biochar. The building sector.
addition of these materials could offer a substantial

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 38
 5.5 Carbon Use Intensity (CUI) is an important 5.6 Regional impact on Scope 3 emissions
metric Material carbon emissions (MCE) are not currently
Understanding the true climate impact of a new home included in municipal or regional inventories, as
necessitates understanding all its related emissions they are the result of industrial and manufacturing
over a period of time. If a municipality or a building operations that typically happen outside the region
company has time-related targets (ie. 50 percent and as such are considered Scope 3 upstream
reduction in emissions by 2030, or net zero emissions emissions. Despite the dispersed nature of the
by 2050), then accounting for the emissions from emissions outside the boundaries of the region,
homes requires adding total MCE and OCE over that policy makers and builders in the GTHA can have
period to ensure that goals are truly being met. This a major impact on these emissions, as the results
is known as “carbon use intensity” (CUI), and is an of this study indicate. Given the urgency to reduce
important lens for considering emissions from the emissions globally, efforts to address MCE from new
region’s homes. homes constructed within the region can have a large
provincial, national and international impact even if
that impact is not on the “emissions ledger” for the
region.

Despite the urgency for immediate and measurable

As we work to climate action, effecting change in the home
building industry can be difficult, with competing
collectively reduce OCE
impacts of cost, aesthetics, material supply, labour
for homes in the GTHA, leaving requirements, durability, performance and occupant
MCE unadadressed will miss the bulk health all needing to be addressed within the scope
of a new home’s overall carbon use of the Ontario Building Code. MCE is a new factor
intensity within the next crucial that needs to be considered in balance with other
demands. As policy-makers and builders have
next few decades.
different priorities and responsibilities, we offer the
following recommendations for addressing MCE that
are specific to both stakeholders.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 39
 Recommendations for Policy Makers
6.1 Existing policy options Support for such efforts might be enhanced by recent
The researchers recommend that municipalities focus developments in the regulation of operational carbon
on establishing appropriate metrics and measurement emissions (OCE) in the British Columbia Building
for entire projects and avoid regulations that focus Code. The province is also in early discussions with
on specific high-emitting materials. The complexities leading municipalities to include MCE in the relatively
of home building may dictate the need to use certain near future.
high-emitting materials, and if these uses can be
The City of Vancouver is embarking in early 2022
offset by low-carbon and/or carbon-storing options
on the design of a program to reduce “embodied
elsewhere in the building, net targets can still be
carbon” (material carbon emissions) by 40 percent
met. Additionally, innovation in material science
by 2030. The report Policy Research on Reducing the
(such as carbon-storing concrete and new bio-based
Embodied Emissions of New Buildings in Vancouver
materials) may turn options that currently have high
contains excellent background information for
emissions into low emitters or even carbon-storing
developing embodied carbon policies, and includes a
materials.
scan of global embodied carbon policies.40
Currently, neither the Ontario Building Code (nor the
The Cities of Nelson and Castlegar undertook the
National Building Code of Canada) address MCE.
Low Carbon Homes Pilot in 2021 “to enhance its
The Ontario Building Code does offer a potential approach to reducing the impact of our buildings
doorway to the regulation of MCE in the form of by taking embodied carbon emissions (also referred
Objective OE1.1: to as material carbon emissions) into consideration
alongside operational carbon emissions.”41 The report
“An objective of this Code is to limit the probability is intended to inform the development of a municipal
that, as a result of the design or construction of program to reduce MCE in 2022.
a building, the natural environment will
be exposed to an unacceptable risk of The City of Langford, BC, announced a “Low Carbon
degradation due to emissions of greenhouse Concrete Policy” in 2021, focused specifically
gases into the air.39” (Emphasis added) on reducing MCE from concrete. “Effective June
1, 2022, all concrete supplied to City-owned or
We recommend that GTHA municipalities request solicited projects, and private construction projects
that the Ontario government consider introducing greater than 50 cubic meters, will be required to be
MCE requirements for Part 9 buildings in a future OBC produced using post-industrial carbon dioxide (CO2)
update, either via integration in the base code or mineralization technologies, or an equivalent which
inclusion in an optional standard that municipalities offers concrete with lower embodied CO2.”42
can opt into under section 97.1 (1) of the Ontario
Municipal Act. As noted above, we recommend any
potential OBC requirements be based on whole
project MCE/MCI metrics/targets rather than by a
prescriptive approach. In Ontario, the Township of Douro-Dummer instituted

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 40
 the voluntary “Sustainable Development Program” The researchers discourage creating policies or
in 2020. This program offers a “40 percent permit programs that use baseline results as a benchmark
fee rebate on all approved projects that meet the for MCE/MCI reductions. As seen in Section 4.2, it is
required greenhouse gas reduction targets, or an 80 possible for homes with different designs to achieve
percent permit fee rebate with combined with net- very similar MCI results based on material selection,
zero ready construction”43 and is the first program but that starting with a higher baseline would allow a
in North America to measure MCE and provide home to show a very large percentage of emissions
incentives for reductions. reduction without achieving low results.

Similarly, tier 2 of the Toronto Green Standard for

6.2 Municipal EPD requirements
low-rise residential projects (version 4) includes
a requirement to meet an MCI target of 250 kg The researchers recommend that GTHA municipalities
CO2e/m2 or less. Tier 2 is voluntary, but incentivized consider signaling an intention to first prefer and
via a significant development charge refund. The then, after a reasonable time, require Environmental
City of Toronto is currently exploring potential to Product Declarations for all construction materials
integrate MCE requirements in the mandatory tier used in municipal construction projects in order to
1 requirements in a future update to the Toronto encourage all manufacturers to begin producing
Green Standards. This general approach of starting product-specific EPDs. Increased product
with municipal incentives for limiting MCE, and transparency would result in more complete and
subsequently exploring a transition to municipal accurate data for tools that measure MCE. This is
requirements, has the advantage of building industry particularly true for concrete, where variations in
familiarity with low MCE approaches in advance of emissions from different manufacturers and/or mixes
future provincial and/or municipal regulations. can affect MCE by as much as 100 percent.

This report recommends an approach that uses an

6.3 Metrics for MCE programs
MCI “carbon cap”. Part 9 homes share a relatively
consistent design and construction approach, and as The researchers recommend that GTHA municipalities
evidenced by this study, the MCI results fall within a work to establish bold MCE metrics and caps/
reasonable close range. With sufficient stakeholder thresholds that bring about staged emission
input, it should be feasible to agree upon targets reductions over time. Following a similar strategy to
for voluntary MCI “absolute targets” and to further the energy step codes in British Columbia, all homes
incentivize builders who meet more stringent would be required to meet the current target and
targets. The broad sample size of this study might incentives applied to encourage projects to meet the
be considered sufficient to establish such a cap or future higher targets earlier.
threshold.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 41
 The choice of a metric for a relatively new field One potential metric to consider is known as “carbon
like material carbon emissions sets an important use intensity” (CUI). This metric combines the material
precedent that may be difficult to change, once carbon emissions of a house with the anticipated
established. It is possible to cause unintended operational emissions over a defined period of time.
consequences in choosing a metric. As seen in the Choosing a timeframe that matches the climate
results of this study, there is a significant difference targets of a municipality enables policies to be aligned
between MCI calculated on gross floor area and with overarching targets. For example, a metric of
habitable floor area. The use of habitable floor area CUI2030 would include the MCE of a home and all
as a basis for MCI deters homes from having large operating emissions until 2030. If the municipality’s
garages and/or unfinished basements, since the overall goal is 40 percent reduction in emissions by
MCE arising from these materials is attributed to the 2030, then the CUI2030 would need to be 40 percent
habitable area, pushing MCI up by 32 percent in the less than today’s benchmark.
samples studied. For this study, this decision was
made as an effort to prioritize emissions based upon CUI is a useful metric, as it allows for flexibility for
serving residents over space for cars and storage. municipalities and builders to meet the CUI threshold
in different ways, concentrating on electrification,
Municipalities seeking to incentivize reductions or improved materials and/or energy efficiency to
regulate MCE could seek a metric that serves other degrees that are practical and meet local needs.
priorities. The researchers experimented with a As noted in NRCan’s Achieving Real Net Zero
number of alternative metrics that could balance Emission Homes, “the Carbon Use Intensity metric
MCE with building size and number of bedrooms as a would enable more accurate accounting for GHGs
proxy for number of occupants “sharing” the carbon from the homebuilding sector, and would also
emissions of a house. While these priorities may allow for regionally appropriate ways to reach CUI
not align with those of each GTHA municipality, we targets.”44 The GTHA region has already established
encourage policy makers to clearly identify priorities methodologies and inventories for the OCE from
that might be combined with MCE to bring about the homes, and this study provides a basis on which to
desired impacts. begin considering MCE so that the two metrics can,
ideally, be combined for new homes.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 42
 6.4 Incentives for reducing MCE 6.5 Stacked benefits for reducing MCE
The researchers recommend municipalities explore The researchers recommend that municipalities
incentives with relatively low program costs and explore the additional opportunities that may exist
complexity that enable municipalities to signal in conjunction with policies to reduce MCE and
leadership in MCE reduction and encourage the include such benefits when proposing policies. GTHA
building community to engage in MCE reductions. municipalities may be able to achieve numerous
stacked benefits from pursuing MCE reductions,
Voluntary incentives have been used in municipalities including:
around the world to encourage early action on MCE
reductions. These incentives include: ✔ Economic opportunities from new regional
manufacturing of low-carbon and carbon-
storing materials. The region has a large
✔ Reduction in planning/permit fees and/or supply of the raw materials required for
faster timelines for approvals for projects improved materials and the manufacturing and
reporting MCE/MCI/CUI with submission transportation infrastructure to support.

✔ Reduction in planning/permit fees and/or ✔ Healthier indoor environments for building

faster timelines for approvals for projects occupants. Carbon-storing materials are
voluntarily meeting a MCE/MCI/CUI cap/ typically free of off gassing and dangerous
threshold chemical content.45

✔ Recognition/awards for projects meeting ✔ Reduced landfill waste volumes. Carbon-

a MCE/MCI/CUI cap/threshold and/or storing materials can more easily be diverted to
projects with lowest recorded MCE/MCI/CUI composting facilities rather than landfill.
in category
✔ Training opportunities for leading educational
institutions in the region. These include courses
✔ “Low-carbon” designation offered to
and programs in low-carbon construction
projects and/or builders meeting a MCE/ at universities, community colleges and
MCI/CUI cap/threshold private career colleges, educating architects,
engineers, home designers, builders and
tradespeople.

✔ Conservation benefits from ecosystem services

provided by sustainably-managed resources for
biogenic materials.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 43
 MCE and the City of Toronto’s Green Standard, V4
The Toronto Green Standard is Toronto’s sustainable design and performance requirements for
new private and city-owned developments since 2010. Version 3 has been in effect since 2018
and Version 4 comes into effect May 1, 2022 for new planning applications. The Standard consists
of tiers of performance with Tier 1 being mandatory and applied through the planning approval
process. Financial incentives are offered through the Development Charge Refund Program for
eligible and verified Tier 2 or better, high performance, low emissions projects.

The Toronto Green Standard Version 3, included a performance pathway to high performance, low
emissions new construction by 2030 based on absolute performance targets related to greenhouse
gas (GHG) emission limits, energy use intensity and thermal energy demand intensity. The staff
report and the City’s Zero Emissions Building Framework study that supported this change set out
a stepped approach to increasingly higher energy and GHG performance measures with each
Toronto Green Standard update for large Part 3 Buildings (which comprise over 85 percent of
projected new construction in Toronto).

In the TGS v4 (2022) a new voluntary requirement has been added for Tier 2 and 3 projects to
conduct a materials emissions assessment of the upfront embodied carbon of structural and
envelope components. This requirement recognizes the importance of the carbon footprint of
building materials and the role of the Toronto Green Standard in planning and decision making.
A requirement for Tier 2 projects to calculate the embodied carbon and the carbon sequestration
within landscape designs has also been added.

The researchers suggest that the TGS v4 could consider using the data from this study to
implement a Part 9 MCI threshold requirement for Tier 2 and 3 projects. The average MCI result
of approximately 190 kg CO2e/m2 (based on the ‘gross floor area’ definition used in municipal
reporting) represent an achievable threshold. Limiting the maximum MCI of homes to this
threshold would reduce emissions in the study by 14.3 percent across all new Part 9 homes in the
region.

“Stretch goals” for Tier 3 of the TGS could also be set to encourage greater innovation. 61 homes
in this study achieved MCI for heated floor area of less than 150 kg CO2e/m2, suggesting that this
may be an appropriate stretch goal. 28 homes had less than 125 kg CO2/m2 of heated floor area,
suggesting an even more ambitious stretch goal.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 44
 Industry Recommendations

7.1 Measuring MCE 7.4 Plan for future material substitutions

The researchers recommend that all new home The researchers recommend that builders set
designs undertake early MCE measurements during MCE/MCI/CUI targets that are achievable within
design development to lower emissions as much as a 2-5 year window and begin design and supply
possible, and use MCE tools to ensure procurement chain work to support such changes. Free tools
prioritizes the material brands with the lowest such as BEAM and MCE2 offer opportunities
MCE. Free tools such as BEAM and MCE2 enable to explore material options that may require
designers and builders to obtain MCE results for additional design and/or procurement changes in
projects with relative ease and simplicity. order to use a material with lower MCE.

7.2 Request EPDs from manufacturers 7.5 Examine design options

for reduced MCE
The researchers recommend that designers
The researchers recommend that builders explore
and builders send requests to manufacturers
design options that reduce MCE in addition to
for product-specific EPDs. Increased product
directly substituting materials. While this research
transparency would result in more complete and
did not directly address design options to reduce
accurate data for tools that measure MCE and in
MCE, the high impact of concrete suggests that
turn provide builders with more options.
designs that minimize below-grade space and
reduce or eliminate concrete floor slabs will achieve
large MCE reductions, as will multi-unit homes
that share party walls and therefore require less
7.3 Explore immediate potential for insulation. Further design analysis using MCE tools
material substitutions could highlight other opportunities for reductions.
The researchers recommend that builders seek to
implement all feasible 1:1 material substitutions
that can reduce overall MCE. Modeling home
designs with free tools such as BEAM and MCE2 7.6 Declare and promote reduced MCE
offers opportunities to compare the MCE for
The researchers hope that home builders will
materials that can be easily substituted for
undertake MCE modeling of their new homes, make
one another.
all efforts to reduce emissions and publicize their
achievements. The 52 percent of Canadians who
are extremely concerned or quite concerned about
climate change46 are among the customers for new
homes. New homes that can declare themselves to
be low-carbon or zero-carbon will be attractive to
such buyers.

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 45
 Endnotes
1 IPCC report: ‘Code red’ for human driven deliberate human activities, i.e., in addition to the removal that
global heating, warns UN chief https://news.un.org/en/ would occur via natural carbon cycle or atmospheric chemistry
story/2021/08/1097362 processes” according to IPCC, 2021: Annex VII: Glossary
[Matthews, J.B.R., V. Möller, R. van Diemen, J.S. Fuglestvedt, V.
2 Pan-Canadian Framework on Clean Growth and MassonDelmotte, C. Méndez, S. Semenov, A. Reisinger (eds.)]
Climate Change (2017). Cat. No.: En1-77E-PDF ISSN: 2561-4169
https://www.canada.ca/content/dam/themes/environment/ 12 Residential Housing Stock and Floor
weather/climatechange/PCF-FirstSynthesis_ENG.pdf Space, NRCan (2018). https://oee.nrcan.gc.ca/
corporate/statistics/neud/dpa/showTable.
3 Canada’s Climate Actions for a Healthy Environment cfm?type=HB&sector=res&juris=00&rn=11&page=0#sources
and a Healthy Economy, 2021. https://www.canada.ca/en/
services/environment/weather/climatechange/climate-plan/ 13 Milton floor area averages, determined by examination
climate-plan-overview/actions-healthy-environment-economy. of data from Milton.
html
14 International Organization for Standardization.
4 Explanation: The “up front” emissions for buildings (2017). Sustainability in buildings and civil engineering
include transportation to the building site and construction works ; core rules for environmental product declarations of
activities, which are not included in this analysis. All of construction products and services. https://www.iso.org/obp/
the emissions in this study are directly associated with the ui/#iso:std:iso:21930:ed-2:v1:en
manufacturing of materials, so we use the term “material carbon
emissions” 15 Archtoolbox: Environmental Product Declarations
(EPDs): A Guide for Architects. https://www.archtoolbox.
5 Simonen, K., Rodriguez, B., McDade, E,. Strain, L. com/materials-systems/sustainability/environmental-product-
(2017) Embodied Carbon Benchmark Study: LCA for Low Carbon declarations.html
Construction. http://hdl.handle.net/1773/38017
16 Additional emissions from the installation and/or use
6 Low Rise Buildings as a Climate Change Solution phases of a product are included (and noted in BEAM) in cases
(2019). Builders for Climate Action. https://www. where emissions are significant and arise from the product’s
buildersforclimateaction.org/whitepaper1.html7 material itself and not the installation period, so that regardless
of the specifics of the installation, a quantifiable amount of
7 Magwood, C., Ahmed, J., Bowden, E., Racusin, J.
emissions will occur. These additional emissions are typically from
(2021) Achieving Real Net Zero Emission Homes. https://www.
direct off-gassing of GHGs from the product during construction
buildersforclimateaction.org/uploads/1/5/9/3/15931000/
and/or occupancy of the home.
bfca-enercan-report-web.pdf
17 ECN Phyllis Classification. https://phyllis.nl/Browse/
8 According to the National Building Code of Canada,
Standard/ECN-Phyllis
each of the five energy performance tiers have two compliance
metrics, overall percent improvement and heat loss reduction. 18 An equivalence factor between CO2 avoidedemissions
Both of these are calculated in terms of percent improvement and sequestration.Pedro Moura Costa, Charlie Wilson. (2000)
over the Reference House based on minimum prescriptive
requirements. The targets for Tier 3 are 20 percent overall Environmental Science Mitigation and Adaptation Strategies for
improvement and a 10 percent reduction in gross space heat loss. Global Change. DOI:10.1023/A:1009697625521

9 Establishing the Average Up-Front Material Carbon 19 Adapted from Srubar et al., A Methodology for
Emissions in New Part-9 Residential Home Construction in the Building-Based Embodied Carbon Offsetting (2021) https://
City of Nelson & the City of Castlegar (2021). https://www. www.aureusearth.com/documents
nelson.ca/DocumentCenter/View/5586/Benchmarking-
Report?bidId= 20 https://www.istructe.org/IStructE/media/Public/
Resources/istructe-how-to-calculate-embodied-carbon.pdf ,
10 Residential Housing Stock and Floor https://www.leti.london/ecp
Space, NRCan (2018). https://oee.nrcan.gc.ca/
corporate/statistics/neud/dpa/showTable. 21 Life Cycle Assessment of Mechanical, Electrical, and
cfm?type=HB&sector=res&juris=00&rn=11&page=0#sources Plumbing in Commercial Office Buildings. Carbon Leadership
Forum (2019). https://carbonleadershipforum.org/office-
11 Negative emissions or carbon dioxide removal (CDR) “is buildings-lca/
the removal of greenhouse gases (GHGs) from the atmosphere by

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 46
 22 Based on an average of acrylic interior paint EPD results 37 Continuus Materials Everboard. https://www.
from Behr, Kelly Moore and Sherwin Williams EPDs collected in continuusmaterials.com/, https://www.cmdgroup.com/
2019. documents/FS/catalogs/ReWallCeilingTile_120612.pdf

23 US EPA, 2018, Greenhouse Gas Emissions from a Typical 38 Endeavour Centre. Zero House: A zero carbon, zero
Passenger Vehicle. https://www.epa.gov/greenvehicles/ net energy, zero toxin, zero waste prefab home (2017). https://
greenhouse-gas-emissions-typical-passenger-vehicle endeavourcentre.org/project/zero-house/?v=e4b09f3f8402

24 The Atmospheric Fund 2021. 2019-2020 Carbon 39 Ontario Building Code, O Reg. 332/12, s.2.2.1(1)
Emissions Inventory for the Greater Toronto and Hamilton Area. https://www.canlii.org/en/on/laws/regu/o-reg-332-12/latest/
https://taf.ca/wp-content/uploads/2021/12/TAF_Carbon- o-reg-332-12.html#Part_2_Objectives_153709
emissions-inventory-GTHA_2021.pdf
40 Zahra Teshnizi, Policy Research on Reducing the
25 Embodied carbon benchmarks for Part 3 buildings in Embodied Emissions of New Buildings in Vancouver (2019).
the Greater Toronto-Hamilton Area. https://drive.google.com/ https://vancouver.ca/files/cov/cov-embodied-carbon-policy-
file/d/13vU61c7_0UINI_LjzODykqAE0sXgNL9S/view review-report.pdf

26 Magwood, C., Ahmed, J., Bowden, E., Racusin, 41 City of Nelson, Low Carbon Building Materials (2022).
J. (2021). ACHIEVING REAL NET-ZERO EMISSION HOMES: https://www.nelson.ca/905/Low-Carbon-Building-Materials
Embodied carbon scenario analysis of the upper tiers of
performance in the 2020 Canadian National Building Code. Pg 42 City of Langford Announces Bold, Low Carbon Concrete
35. Policy (2021). https://www.langford.ca/city-of-langford-
announces-bold-low-carbon-concrete-policy/#!
27 New, Ontario-specific concrete EPD data is due to be
published in Summer, 2022 43 Township of Douro-Dummer, Sustainable Development
Program (2019). https://www.dourodummer.ca/en/building-
28 CRMCA member industry-wide EPD for Canadian ready- and-renovating/sustainable-development-program.aspx
mixed concrete, EPD10092. NSF (2017). https://info.nsf.org/
Certified/Sustain/ProdCert/EPD10092.pdf 44 Magwood, C., Ahmed, J., Bowden, E., Racusin,
J. (2021). ACHIEVING REAL NET-ZERO EMISSION HOMES:
29 https://www.buildingtransparency.org/ec3 Embodied carbon scenario analysis of the upper tiers of
performance in the 2020 Canadian National Building Code. Pg.
30 CarbonCure’s Impact on the Global Warming 32.
Potential (GWP) of Concrete. https://go.carboncure.com/
rs/328-NGP-286/images/CarbonCure%20Impact%20on%20 45 Magwood, Chris. Opportunities for CO2 Capture
Global%20Warming%20Potential%20of%20Concrete.pdf and Storage in Building Materials (2019). Pg 61. DOI: 10.13140/
RG.2.2.32171.39208
31 As an example, Blue Planet makes aggregate from
waste stream CO2 that the company claims mineralizes 440 kg of
CO2 per tonne of aggregate. https://www.blueplanetsystems.
com/ 46 Abacus Data, Recent extreme weather has more
Canadians worried about climate change’s impact on their health
32 CalStar Brick SMaRT Environmental Product Declaration. (2021). https://abacusdata.ca/extreme-weather-climate-change-
http://mts.sustainableproducts.com/CalStar%20EPD%20 choices/
Document_Final.pdf

33 Hans-Peter Schmidt, Kathleen Draper, Biochar building

material for a climate neutral future (2020). https://www.
mikrobihotelli.fi/wp-content/uploads/2020/10/Biochar-based-
building-materials.pdf

34 The researchers used the second-highest MCI sample,

as the highest MCI sample is a very large custom home and does
not represent a typical typology in the study.

35 Iso-Stroh blown-in insulation made from 100% wheat

straw. https://www.iso-stroh.net/

36 https://durrapanel.com/, https://kodukuubis.com/
en/about-straw-panel/, https://ekopanely.co.uk/, https://
coobio.com/

Builders for Climate Action & Passive Buildings Canada • Emissions of Materials Benchmark Assessment for Residential Construction 47