Heating, ventilation

and air conditioning

(HVAC) equipment
A guide to equipment eligible for
Enhanced Capital Allowances

Heating, ventilation and air conditioning (HVAC) equipment

Contents
Boost your cash flow
Introduction 03
03
1. Check its on the Energy Technology List 03
Background 03
Setting
2. Complete
the scene
your business tax return

03
04

Benefits
3. Start saving
of purchasing
from day
ETL
one
listed products 05
06
HVAC
What technologies
equipment eligible
qualify?
under the ECA scheme
Find out more about ECAs and the ETL

07
05
07

HVAC zone controls

06

Close control air conditioning equipment

09

Further information

11

Heating, ventilation and air conditioning (HVAC) equipment

Introduction

Setting the scene

Enhanced Capital Allowances (ECAs) are a straightforward

way for a business to improve its cash flow through
accelerated tax relief. The scheme encourages businesses
to invest in energy saving plant or machinery specified in
the Energy Technology List (ETL) to help reduce carbon
emissions, which contribute to climate change.

Heating, ventilation and air conditioning (HVAC)

equipment can be used for a range of environmental
conditioning and control applications in buildings.
It includes equipment that provides heating, cooling and
ventilation and equipment that allows the environmental
conditions in a zone (specific controlled area) to be
independently controlled to meet the desired conditions.
This allows environmental parameters such as internal
air temperature, relative humidity and ventilation to be
controlled in relation to thermal heat gains and losses and
occupancy patterns.

The ETL is a register of products that may be eligible for

100% tax relief under the ECA scheme for energy saving
technologies1. The Carbon Trust manages the list and
promotes the ECA scheme on behalf of government.
This leaflet gives an overview of equipment specified
in the heating, ventilation and air conditioning category
on the ETL and illustrates the reductions in energy bills
that can be realised by investing in qualifying ETL energy
saving equipment over non-qualifying equipment.

Background
The ETL comprises two lists: the Energy Technology
Criteria List (ETCL) and the Energy Technology Product List
(ETPL). The ETCL defines the performance criteria that
equipment must meet to qualify for ECA scheme support;
the ETPL is the list of products that have been assessed
as being compliant with ETCL criteria.

Further information
For more information on HVAC, visit
www.carbontrust.com/resources/reports/advice/
technology-and-energy-management-publications
or download the Carbon Trusts Heating, ventilation
and air conditioning overview (CTV046)

Close control air conditioning equipment is used to

control the temperature (and relative humidity where
necessary) in rooms and enclosures containing heat
generating equipment, such as servers, computers
or telecommunications devices, and in some types of
manufacturing process (e.g. clean rooms).
Other applications include:
rooms or buildings that contain temperature and
humidity sensitive equipment such as calibration
and test areas.
processes which require clean environments, for
example electronics and pharmaceutical manufacturing.
Close control air conditioning equipment is often used
in areas that require constant high levels of cooling and
therefore use large amounts of energy. The use of energy
efficient close control air conditioning equipment, such
as that listed on the ETL, can result in significant energy
savings and, therefore, reduced energy bills.
In buildings without individual zone control, levels of
heating and/or cooling can be the same throughout
the building. This can result in large amounts of energy
wastage and associated high CO2 emissions.
Splitting the building into a number of separate zones can
provide control that more closely matches the desired
conditions and actual occupancy patterns. The selection
of control zones will be influenced by the following:
Internal heating/cooling requirements based on the
number of occupants, amount of office/IT equipment
and other sources of heat in different areas of the
building.
Occupancy patterns whether separate parts of the
building are occupied for different time periods, for
example, a single area with 24-hour occupancy or
evening work.

Eligibility for ECAs is based on a number of factors. Visit http://etl.decc.gov.uk/etl to find out more.

Heating, ventilation and air conditioning (HVAC) equipment

External heat gains increased solar gain on southerly

facing areas of the building.
The technologies specified in the HVAC category are:

The functionality of an HVAC zone controller will depend

on the specific intended application; however, an example
zone controller is shown below.

HVAC zone controls.

Close Control Air Conditioning Equipment.
Other HVAC technologies, such as boilers, optimising
controls, heat pumps and chillers, are described in other
technology areas of the ETL.
The level of energy savings resulting from the use of zone
controls will depend on the specific application, however,
properly installed and commissioned controls typically
provide energy savings of around 20%2 over systems
without this level of control. In recognition of this, The
Building Regulations Approved Document L2A (ADL2A).
Conservation of fuel and power in new buildings other
than dwellings (2010) advises that, in order to achieve
compliance, HVAC systems should be sub-divided into
separate control zones to correspond to each area of the
building that has a significantly different solar exposure
or pattern or type of use. Each separate control zone
should be capable of independent timing and temperature
control and, where appropriate, ventilation and air
circulation rate. Also if heating and cooling are provided
in the same zone, they should be controlled so as not to
operate simultaneously. In addition, they should also meet
the specific control and efficiency standards are laid out
in the 2010 Non-Domestic Building Services Compliance
Guide (NDBSGC).
For existing buildings, Approved Document L2B (ADL2B)
Conservation of fuel and power in existing buildings
other than dwellings requires this level of zone control
where work involves the provision or extension of
controlled services (i.e. HVAC systems).
It should be remembered that the control specifications
in the ADLs and NDBSGC are minimum standards and
those listed in the ETL have far more functionality.
HVAC zone controls can also help optimise occupant
comfort, health and productivity. In a building with a
single control zone, areas within the building may be
either over-heated or under-cooled. This will cause
occupants discomfort and have a detrimental impact
on their productivity. By splitting the building into an
appropriate number of control zones, the comfort of the
occupants can be improved, which normally results in
increased productivity.

Figure 1 Schematic of a zone controller

Analogue input(s)
from sensors

Binary input(s)

Control
strategy
Operational
parameters

Analogue output
to value(s)

Binary output to
switch equipment
on/off

The HVAC zone controller will have a factory-set

control strategy for each function. There will also be
manual settings for variable operational parameters,
which are initially set during the commissioning stage.
Examples include zone occupation times, desired internal
temperatures and levels of ventilation. The zone controller
will have one or more control inputs such as that from an
internal air temperature sensor (analogue input) and/or
binary inputs, for example from an occupancy presence
detector. Control outputs can include analogue outputs
(for example, a control signal to adjust the position of a
valve) or binary outputs to switch an item of equipment
on or off.
Some zone controllers can be connected together using
a communications network, to an overall controller.
This allows the sharing of data, for example, readings of
external air temperature can be shared between individual
zone controllers on a network.

Heating, ventilation and air conditioning (HVAC) equipment

Benefits of purchasing
ETL listed products

HVAC equipment eligible

under the ECA scheme

Close control air conditioning products listed on the ETL

can use significantly less energy than non-ETL listed
products. ETL listed products achieve a higher overall
energy efficiency by using more efficient components
such as compressors, heat exchangers and controls, and
may also incorporate free cooling coils.

HVAC equipment eligible under the ECA scheme

includes the following two categories; HVAC zone control
equipment and close control air conditioning equipment.
These are described below.

HVAC zone control products listed on the ETL are those

that facilitate a more efficient operation of HVAC systems
to ensure that energy is consumed only when required,
reducing energy waste and CO2emissions. An average
site can potentially achieve energy savings of between
8% and 30%2,3 through correct application of ETL listed
HVAC zone controls.
When replacing equipment, businesses are often tempted
to opt for that with the lowest capital cost; however, such
immediate cost savings can prove to be a false economy.
Considering the life cycle cost before investing in
equipment can help reduce costs and improve cash flow
in the longer term.
The ECA scheme provides businesses with 100% first
year tax relief on their qualifying capital expenditure.
This means that businesses can write off the whole
cost of the equipment against taxable profits in the year
of purchase. This can provide a cash flow boost and an
incentive to invest in energy saving equipment which
normally carries a price premium when compared to less
efficient alternatives.
This leaflet also illustrates the reductions in energy
consumption, carbon emissions and energy bills that can
be realised by investing in qualifying ETL energy saving
equipment over non-qualifying equipment.

Important
Businesses purchasing equipment must check
the ETPL at the time of purchase in order to verify
that the named product they intend to purchase
is designated as energy saving equipment.
HVAC zone control equipment that meets the ETL
eligibility criteria but is not listed on the Energy
Technology Product List (ETPL) at the time of
purchase is not eligible for an ECA.

2 
CTL025

HVAC zone controls4

The ECA Scheme covers HVAC zone controls that
are specifically designed to automatically control in
an energy efficient manner, the amount of heating,
cooling, ventilation or air conditioning that is applied
to individual rooms or defined areas within a building,
known as zones. In general, these controls are applied
to five types of HVAC equipment:
Wet (hydronic) heating systems.
Underfloor or storage heating wet systems
and electric heating.
Ventilation.
Air conditioning and comfort cooling.
Chilled water systems.
NOTE: In practice many zone controls may regulate more
than one system within the zone, i.e. both the heating
and ventilation; however, this will depend on the specific
application.
Wet heating system
The use of zone controls for hydronic heating
systems is important to ensure that overheating is
avoided. ETL compliant zone controls can be applied
to constant and variable flow approaches to wet heating
system control.
The schematic diagram below illustrates the use of a
zone controller applied to a constant volume/variable
temperature zone heating circuit.

How to implement electric heater controls, Carbon Trust, www.carbontrust.com;

CTV032 Building controls - Realising savings through the use of controls, Carbon Trust, August 2007, www.carbontrust.com;
4 
The descriptions of the HVAC zone controls given in this leaflet are examples only and do not constitute ECA eligibility. The formal criteria and details
governing the ECA scheme can be found at http://etl.decc.gov.uk/et
3

Heating, ventilation and air conditioning (HVAC) equipment

Figure 2 Constant volume/variable temperature zone

heating circuit
Common header

Zone
controller
Pump Flow temp.
sensor

Primary inlet

Mixing inlet
Secondary return

Load
Zone air
Outside air
temp.
sensor temp. sensor

require visually unobtrusive heat emitters. Figure 3 shows

a simplified two-zone underfloor hydronic heating system.
Each heating zone has its own controller that allows
for the independent regulation of the heated water in
response to the internal air temperature and a defined
occupancy time schedule.

Figure 3 Hydronic underfloor heating

Flow bar
Flow
Return

With this approach, the zone controller will activate

the heating circuit based on the set time schedule for
the zone. This allows different time schedules for
different zones. The temperature of the water flowing
through the heat emitters (e.g. radiators) is regulated
by the zone controller based on the internal air
temperature and an outside air temperature sensor.
This type of weather compensation is a requirement
for ETL compliant products.
Other features of ETL compliant products include
optimum start. This activates the heating circuit at an
early enough time in the morning to ensure that the zone
air temperature reaches the desired set-point by the
beginning of occupancy and not several hours earlier.
ETL compliant zone controls can also control non-hydronic
heating systems including electric storage heating, gasfired convection heaters and gas-fired radiant heaters.
For the installation of wet heating zone
controls where none previously existed within
a typical 1,000m2 naturally ventilated cellular
office building, using 151kWh/m2/year for space
heating, the potential annual savings at 20% are
calculated as:
908.
30,200kWh.
5.5 tonnes CO2.
Underfloor heating
Underfloor heating systems can be used in buildings
where there is a danger of people injuring themselves,
where there is a risk of vandalism, and in areas that

Mixer manifold

Zone
controller

Heating
circuit 1

Outside air temp.

Zone
Floor surface temp. controller

Heating
circuit 2

Zone
controller

Electrothermic head

Zone air temp.

The alternative to hydronic underfloor heating is electric

underfloor heating, provided by coils buried in the floor.
This can either be controlled by the zone temperature
or by varying the current supplied to the underfloor
heating circuit. A zone high-temperature override disables
the electrical control signal when the air temperature
in the zone rises above a certain temperature. In order
to avoid damaging the floor surface a high-temperature
override disables the electrical current when the floor
temperature rises above a temperature set-point.
For the installation of electric underfloor heating
zone controls where none previously existed
within a typical 1,000m2 naturally ventilated
cellular office building, using 151kWh/m2/year
on heating, the potential annual savings
at 20% are calculated as:
2,718.
30,200kWh.
15.8 tonnes CO2.

Heating, ventilation and air conditioning (HVAC) equipment

Ventilation
With improvements in building fabric insulation and
levels of air-tightness (reduced air infiltration), the relative
contribution that ventilation makes to a buildings energy
consumption is increasing. The ventilation to a zone can
be controlled by the following means:
Time schedules this is the most basic level of
automatic control and allows for automatic switch on/
off in relation to set occupancy patterns. This form of
control is suitable where the level of occupancy is fairly
consistent and/or predictable. Where this is not the
case, ventilation control can be improved by using zone
controls that allow the occupants to alter the fan speed
and hence vary the ventilation rate.
Occupancy detection this allows for the automatic
switch on/off of the ventilation system if occupancy
is detected in the zone. This helps to reduce energy
consumption by ensuring that the ventilation system
only operates when the zone is occupied. There is
a range of occupancy detection products, the most
common being passive infrared (PIR). Occupancy
detection can be suitable for zones that are
intermittently occupied. Examples include
conference facilities and storage areas.
Demand-controlled ventilation this approach allows for
the optimisation of energy consumption and indoor air
quality. Typically, levels of metabolic CO2 are measured
and used as a control input (the greater the occupancy
density, the higher the level of CO2). The speed of
the ventilation fan is controlled to give a desired level
of CO2. Demand-controlled ventilation is suitable when
levels of occupancy within the zone are highly variable
and where good indoor air quality is important (for
example in a conference room). Figure 4 illustrates the
control of a demand-controlled ventilation system.

Figure 4 Demand-controlled ventilation

Signal from CO2 sensor
Zone controller

Air supply

Fan speed
control
signal

CO2 sensor

Ventilation zone

Air handling
unit

For installation of ventilation zone controls where

none previously existed within a typical 5,000m2
air-conditioned office building, using 109kWh/m2/
year electricity and 178kWh/m2/kWh of gas for
space heating and cooling, the potential annual
savings at 20% are calculated as:
3,030.
57,400kWh.
17.9 tonnes CO2.

Heating, ventilation and air conditioning (HVAC) equipment

Air conditioning and comfort cooling

There are a wide range of air conditioning and comfort
cooling systems, including constant air volume
systems, variable air volume systems (VAV), fan coils
and heat pumps.
As with hydronic heating systems, zone controls can
play an important role in ensuring that air conditioning
and comfort cooling systems maintain desired internal
conditions without wasting energy.
The schematic diagram below illustrates the control
of a fan coil unit (waterside control).

Figure 5 Fan coil unit (waterside control)

Heating

Cooling

Air from AHU

or zone

Zone air
temp.

Fan coil
controller

Fan operation
Fan speed

Fan

Supply air
to zone

For the installation of cooling system zone

controls where none previously existed within a
typical 1,000m2 air-conditioned office building,
using 109kWh/m2/year electricity for space
cooling, the potential annual savings at 20%
are calculated as:
1,962.
21,800kWh.
11.4 tonnes CO2.

Chilled water systems

Chilled water systems comprise chillers that generate
chilled water and their associated equipment such as
heat rejection units and pumps. By their nature, chilled
water systems are centralised and usually located in a
plant room. The generated chilled water is distributed to
items of equipment such as fan coil units, close control
air conditioning equipment and chilled ceilings/beams
located throughout a building. Chillers are normally
supplied with controls already installed and configured
by the manufacturer. It is the supply of chilled water
produced by a chiller that is controlled at the zone
level by zone controllers.

Cooling value
Heating value

A fan coil unit provides heating and cooling to the

surrounding zone, whilst aiding zone air distribution.
Outside air can be supplied to the unit or the zone either
directly from outside, or from an air handling unit.
The unit incorporates a fan, a heating coil and a chilled
water-cooling coil, and also induces air from the
surrounding zone. The coils are controlled to achieve
the required supply air temperature to the zone; if
supplied with water they utilise three-port mixing valves
in a diverting application to obtain the required heating/
cooling effect. The operation of the coils is sequenced
so that heating and cooling are never provided at the
same time. The fan can either be:
constant speed;
two-speed; or
variable speed.
Variable speed control can be achieved with the use of DC
electric motors to drive the fan.

Information for purchasers

For further information about the ECA scheme,
the Energy Technology List (ETL) and other
Technology Information Leaflets in the series
please visit http://etl.decc.gov.uk/etl or contact
the Carbon Trust on +44 (0)207 170 7000 or
email info@carbontrust.com.

Heating, ventilation and air conditioning (HVAC) equipment

Close control air conditioning equipment

Close control air conditioning equipment is designed
to control the temperature in rooms and enclosures
containing heat-generating equipment, or processes
with high sensible heat loads. It also offers the option
to control relative humidity. ETL listed close control air
conditioning products must have a sensible cooling
capacity to total cooling capacity ratio of at least 90%.
Close control air conditioning units are typically used:
in rooms containing servers or other computer, electronic
and telecommunications related equipment; or
where temperature sensitive industrial or laboratory
processes are carried out.

Close control air conditioners containing an

electrically powered compressor
The diagrams below show a number of potential different
configurations for close control air conditioning equipment
that incorporates an electrically powered compressor.

Figure 6 Direct expansion system (DX)

air cooled (without free cooling)
close control air conditioning units
Indoor unit
Evaporator
Heat
in
Outdoor unit

This equipment often operates continuously and has a

much higher sensible cooling load requirement per unit
floor area than conventional air conditioning applications.
Close control air conditioning accounts for around 40% of
all UK packaged air conditioning energy consumption and
around 20% of the entire air conditioning sector5.
Energy savings may be delivered by selecting more
energy efficient close control air conditioning products.
Manufacturers can make more energy efficient products
by using more efficient components such as fans and
fan motors, compressors, electronic expansion valves
and larger heat exchangers, and by incorporating free
cooling coils.
Close control air conditioning products may either consist
of a single-packaged unit, or two or more factory built subassemblies that are designed to be connected together
during installation. A unit may contain an electrically
powered compressor(s) and/or incorporate a chilled water
cooling coil for connection to an external chilled water
(CHW) circuit.

Heat
out

Refrigerant pipes
Compressor

Condenser

Figure 7 DX air cooled with integral chilled water free

cooling coil(s) close control air conditioning units
Indoor unit
Evaporator
& free
cooling coil
Compressor

Heat
in

Outdoor unit
Heat
Refrigerant pipes
out
Chilled water pipes

CHW/free
cooling
system

Figure 8 DX water cooled (without free cooling)

close control air conditioning units
Indoor unit
Evaporator

Heat
in

Compressor
Condenser
CHW system

5 
DEFRA

market Transformation Programme Air Conditioning Sector Model.

Heating, ventilation and air conditioning (HVAC) equipment

The following assumptions have been made

in these scenarios:
Electricity price 9p/kWh.

10

Chilled water (CHW) close control air conditioners

Chilled water (CHW) close control air conditioning units
contain a chilled water cooling coil for connection to an
external chilled water (CHW) circuit.

Electricity CO2 emission factor: 0.524 CO2/kWh.

Annual savings do not degrade.

Indoor unit

Figure 9 DX water cooled with integral chilled water

free cooling coil(s) close control air conditioning units

CHW
cooling coil

Heat in

Indoor unit
Heat in

Evaporator
& free
cooling coil

CHW system
CHW/free
cooling system

For the installation of an ETL listed 80kW chilled

water close control air conditioning unit in place
of an existing non ECA-listed unit, the potential
annual savings are calculated as:

Compressor
Condenser

For the installation of an ETL listed 60 kW DX aircooled close control air conditioning unit in place
of an existing non ECA-listed unit, the potential
annual savings are calculated as:
1,643.
18,250kWh.
9.6 tonnes CO2.
Based on the following scenario:
Installation of one 60kW DX air-cooled close control air
conditioning unit with an average EER of 2.7.
Replacement of a 60kW DX air-cooled close control air
conditioning unit with an average EER of 2.4.
The close control air conditioning unit operates for 365
days a year at an average load of 75%.

1,898.
21,087kWh.
11 tonnes CO2.

Based on the following scenario:

Installation of one 80kW chilled water close control air
conditioning unit with an average EER of 16.7.
Replacement of a 80kW chilled water close control air
conditioning unit with an average EER of 10.0.
The close control air conditioning unit operates for 365
days a year at an average load of 75%.

Heating, ventilation and air conditioning (HVAC) equipment

11

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ECA762

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