Definition

Zero-energy building (ZEB), also called net zero-energy building, any building or
construction characterized by zero net energy consumption and zero carbon
emissions calculated over a period of time. Zero-energy buildings (ZEBs) usually
use less energy than traditional buildings as well as generate their own energy on-
site to use in the building; hence, many are independent from the national
(electricity) grid. ZEBs have emerged in response to stringent environmental
standards, both regulatory and voluntary, introduced to address increasingly
significant environmental issues such as climate change, natural resource
conservation, pollution, ecology, and population.
Many people in developing countries (and elsewhere) already live in zero-energy
buildings out of necessity, including huts, tents, and caves exposed to temperature
extremes and without access to electricity. The notion of a “zero-energy building”
in a modern sense has been discussed since the 1970s, prompted by the
petroleum shocks of the decade and subsequent concerns about the
consequences of fossil fuel dependency. Definitions of ZEBs vary from those
related to net energy inputs versus outputs to those that balance the financial
costs of energy use with the costs associated with equipment used in the
structure for energy production—from photovoltaics (solar cells) and wind
turbines, for example—combined with the benefits associated with exporting
energy generated by the structure. The energy in a building can be measured in
many ways (e.g., cost, energy, or carbon emissions), and different views exist on
the relative importance of energy production and energy conservation in
achieving a net energy balance.
 Background
The concept of zero energy building began with the increased problems faced due
to various environmental issues such as climate change, global warming,
pollution, and ecosystem conservation.

The concept of low energy building was put forward for the first time by German
scholar Wolfgang Feist and Swedish professor Bo Adamson

Ultimately, in 1990, in Germany, the first energy-efficient building was

constructed which marked the beginning of the development of a new
environmentally friendly building construction technology i.e. Zero Energy
Building.

To conduct further research on this emerging concept and for its further
advancement, in Darmstadt Germany, the Passivhaus Institut was founded in the
year 1996.

Since then, the institute has been successful in constructing 15,000 such buildings.

The World Business Council for Sustainable Development has even undertaken a
major initiative regarding the development of zero energy building.
 Mechanism of zero energy building

As depicted in the figure above, the mechanism of zero energy building involves
the transfer of energy to and from the building such that the amount of energy used
and the amount of energy delivered is equal.

The energy needs of the building mostly include lighting, electrical appliances,
heating, cooling, hot water, etc.

To meet these energy needs, it produces or generates energy utilizing several

renewable sources such as solar cells provided at the site.

Several micro-generation techniques of energy production are used which may be

listed as follows:

1. Wind turbines

2. Solar cells

3. Biogas
4. Small scale hydro-power.
 How does a building achieve net zero energy ?
Several factors go into designing an energy-efficient building that achieves net
zero energy goals.
Location

To construct a net zero energy building, you must take several conditions into
consideration. The building site, where you are building, the climate and the
building’s exposure all have an effect.

Among other things, take into account:

Climate
Sun
Wind patterns
Temperature
Rain patterns

Orientation

The orientation of the building depends on the success of achieving net zero
energy. Certain renewable energy generation mechanisms, like solar panels, work
best when the building is facing south.

But factors that conserve energy are also important. Besides harnessing the sun’s
energy, you can conserve by orienting your building to take maximum advantage
of the shade. In warm climates, this means you’ll need to use the air conditioning
less to keep your building cool.

Lighting is another important factor. Lighting systems can account for almost 25%
of a building’s total energy consumption. Orienting your building to take
advantage of natural lighting can reduce that load. Window arrangement and the
use of skylights are strategies that can be considered when deciding on a
building’s orientation.

You can also situate your building to take advantage of natural breezes. Using
natural resources to power your building’s energy systems and reduce energy
requirements, will conserve resources at the same time.
Design

Building design is next. Make sure to select the best-insulating materials possible
so the building conserves as much energy as possible. Windows (dual- or, better,
triple-pane and effectively sealed) can pose a major factor in conserving energy.

Passive strategies aren’t about energy production. They’re about minimizing

energy usage — and maximizing energy performance. In fact, they operate
without energy use, which is why they help buildings achieve net zero energy use:

High-efficiency appliances require less energy and lighten the overall energy
load.
Low-energy HVAC systems do the same.
Air sealing prevents cooled or heated air from escaping through cracks, often
around openings such as windows and doors. This results in less need for air
conditioning or heating to maintain climate control.
 Insulation performs the same function by providing an extra barrier between
the interior and exterior of a building. This layer traps heat (in winter) and cool air-
conditioned air (in summer) that otherwise might escape through walls, ceilings,
etc.

The effectiveness of insulation is rated in R-values. These vary based on the

thickness, density, and type of insulation: the higher the R-value, the better. Types
of insulation include:

Fiberglass
Wool
Foam boards or blocks
Cellulose
Polystyrene
Polyisocyanurate
Polyurethane

Ventilation is particularly important in tropical climates. It’s necessary to replace

stale air with fresh air. This can help to moderate internal temperature while
reducing the build-up of moisture that can cause mold and bad odors. The energy
used to maintain proper ventilation, by using electrical fans, for example, can be
reduced significantly by employing natural strategies.
Architectural design in new buildings maximizes efficiency and promotes
sustainability.

ASHRAE, or the American Society of Heating, Refrigeration, and Air Conditioning

Engineers, has created standards that apply to building design. The group,
founded in 1894, has 87 active standards and guideline project committees that
address some of the following topics:

Thermal comfort
Energy conservation in buildings
Reduction of refrigerant emissions
Indoor air quality

Renewables

The final step in designing high-performance buildings is determining the most

relevant renewable energy sources based on the building. If the building is
industrial scale, wind generators might be used on-site rather than off-site. Solar
panels might be the way to go for new homes or even ones that can be converted.

Active strategies reduce energy consumption during the building process through
the use of renewable energy strategies, such as:

Photovoltaics — Photovoltaics is the direct conversion of light into electric

power using semiconducting materials such as silicon. Each solar panel contains
numerous photovoltaic cells, which work together to produce electricity.
Wind power — Wind is a kind of solar energy produced by three factors. It’s
affected by the sun unevenly heating the atmosphere, irregularities in the Earth’s
surface, and the planet’s rotation. The resulting wind turns propeller blades
around a rotor, which spins a generator, creating electricity. Wind farms in
mountain passes near San Bernardino (San Gorgonio Pass) and Northern
California (Altamont Pass) contain hundreds of huge propellers.
 Hydroelectric power — Hydroelectric plants capture the energy of falling water
and convert it into electricity. Water flows downhill and is captured by a reservoir
behind a dam. This reservoir acts like a battery, releasing water during periods of
peak demand to produce power.
Biomass — Biomass stores chemical energy from the sun, produced by plants
through photosynthesis. It can be burned directly to produce heat or can be
converted into renewable liquid and gas fuels. Biomass can be as simple as a log
on a fire. It’s like a solar battery, which releases bioenergy.
Geothermal power — Geothermal power involves water pressure in the form of
steam. Geothermal wells drilled a mile or two underground pump hot water to
the surface. There, the pressure drops and the water turns into steam. The steam
spins a turbine connected to a generator, producing electricity.
Solar power — Sunlight shining on a panel is absorbed by photovoltaic cells in
the panel. This creates an electrical charge in response to an electrical field in the
cell, producing electricity.
Solar thermal — Solar thermal power systems use mirrors to collect sunlight
and concentrate it. This raises the temperature until it is high enough to produce
electricity. Examples include curved parabolic troughs, such as those used in the
Mojave Desert.

Net zero energy buildings react in various ways to their local electricity grid.
Whether the grid is integrated or conventional affects the way it interacts with
buildings and strategies (such as renewable energy sources).

Energy moves between the grid and conventional energy buildings in a single
direction. It flows from the grid to the building, utilizing conventional metering.
Moderately responsive buildings have interactive demand response.
Buildings that are fully integrated with the grid include passive efficiency
features as well as renewable energy production onsite.
Put another way, the two types of ZNE building typologies must work together to
optimize grid performance:

Renewable-oriented (active strategies)

Efficiency-oriented (passive strategies)

Utilizing both passive and active strategies will prove most beneficial to the
relationship between the utility grid and ZNE buildings
 Relationship between net zero energy building and the
grid.
Despite the increased production of renewable energy, we don’t have the
technology to store the energy on a large scale. Hydroelectric dams alone aren’t
nearly enough.

As discussed earlier, a grid connection is needed to help buildings achieve net zero
energy. It sends any excess energy buildings produce back to the utility grid.

This involves a concept called load flexibility, under which demand can be shifted
to accommodate fluctuations in wind and solar supply. There will be times of peak
demand. But there will also be times when surplus power is generated using active
renewable energy strategies.

Load flexibility involves full connectedness to the grid, which works like this:

 Integrating a building with the grid to produce your own energy lets you rely
on that energy when climate conditions allow. In other words, you produce
energy when the sun is shining, water is running, or the wind is blowing.
 Any excess electricity you produce during these periods is fed back into the
grid. Most states and utilities employ net metering, which “turns back” your
electricity meter as you send power to the grid. Utility grids need to be
responsive and interactive. They need to work with all types of renewable
energy sources to attain net zero energy.
 When conditions don’t allow you to create your own energy, you can access
energy supplied by the grid. This means when the sun isn’t shining, water
isn’t running, and the wind isn’t blowing.
 To pursue this option, you’ll need to know:
o What equipment you need to connect to the grid, including meters,
power conditioning equipment, and safety equipment.
o What requirements your power provider has set.
o What state and community codes and requirements you’ll have to
meet.
There are two different net zero building typologies: renewable-oriented and
efficiency-oriented.

 Renewable-oriented buildings:
o Use more energy but also generate more energy.
o Rely on active strategies such as mechanical HVAC systems, thermal
storage, demand response, and night ventilation.
 Efficiency-oriented buildings:
o Use and generate less energy.
o Rely on passive strategies like effective insulation, built-in shading,
daylighting, and building orientation.

The Future of Net Zero Energy Buildings.

 Billions of buildings need to be renovated or built at net zero to reduce global
warming and meet the Paris Agreement.

Sharing these goals, the National Renewable Energy Laboratory works on the
research and development of renewable energy and energy-efficient technologies.

The current U.S. presidential administration’s American Jobs Plan seeks to invest
$2 trillion in jobs, renewable energy, and renewed infrastructure.

This investment will impact the climate crisis by:

Providing infrastructure to reduce impacts on the environment and

communities.
Supporting clean energy technologies to lessen the impact of greenhouse gases.
Removing current environmentally damaging energy sources.

The Department of Energy has set goals or metrics to focus on energy efficiency
and renewable energy. Among them:

Deploy 30 gigawatts of offshore wind within the decade. This will help:
Create jobs for Americans.
Reduce carbon dioxide emissions.
Generate clean energy to power millions of homes.
Cut the current cost of solar energy by 60% by 2030 by improving solar
technology and supporting new jobs. This will help put the U.S. on a path to
achieving 100% clean electricity by 2035.
 Case Study
 First zero energy building in India
 Packard foundation headquarters
 Stevens library at sacred heart school
 Advantages of ZEB’s Disadvantages of ZEB’s

1. Increased comfort due to 1. Initial cost can be higher –

more uniform interior effort required to
temperature understand , apply , and
qualify for ZEB subsidies
2. Extra cost is minimized for 2. Very few designers or
new construction compared builders have the necessary
to an afterthought retrofit. skills or experience to build
net zero energy buildings
3. Reduced requirement for 3. Challenge to recover
energy austerity. higher initial cost on resale
of building – appraisers are
uniformed – their model do
not consider energy.
4. More scalability and 4. Climate – specific design
reliability of the design may limit future ability to
procurement and respond to rising or falling
construction process leads to ambient temperatures
less time frame for the (Global Warming).
project. Thus, the financing
cost is less.
5. Higher resale value as 5. Without an optimized
potential owners demand thermal envelope embodied
more zero net energy energy and resource usage is
buildings than available higher than needed.
 supply.
6. Future legislative
restriction, and carbon
emission, taxes/ penalties
may force expensive retrofits
to inefficient buildings.
7. Using standardized
building technique and
energy cost modelling these
buildings can be very
affordable to build.

Conclusion
References