NOTE: This section sets out minimum Building Regulations standards for fixed building services and other systems.
Best practice is to achieve higher efficiencies than these minimum standards.
NOTE: The Ecodesign for Energy-Related Products Regulations 2010 set the efficiencies and standards that must be met when introducing new energy-using products to the market. This approved document sets standards that should be met when installing fixed building services or on-site electricity generation. In cases where the Energy-Related Products Regulations and the Building Regulations both apply, both standards should be met.
6.1 This section sets out minimum standards for specific types of building services. The minimum efficiencies set out are based on documented manufacturers’ test data. Note that test results will always be based on the equipment’s operation under particular conditions. Equipment should be designed, specified and installed with the aim of maximising its efficiency as-installed.
Boilers
NOTE: This subsection applies to wet central heating systems that use commercial boilers fired by natural gas, liquid petroleum gas, oil or biomass. Steam boilers are not covered. Electric boilers are dealt with in a separate subsection.
6.2 In addition to meeting the general requirements for heating systems in Section 5 and following paragraphs 6.7 and 6.8, a boiler should meet either of the following.
a. For new buildings, the seasonal efficiencies in Table 6.1.
b. For boiler plant installed in existing buildings, the seasonal efficiencies, or the overall seasonal efficiency for multiple-boiler systems using non-identical boilers, in Table 6.2.
Table 6.1 Minimum heat generator seasonal efficiency for boiler systems in new buildings
Table 6.2 Minimum heat generator seasonal efficiency for boiler systems in existing buildings
Single-boiler systems and multiple-boiler systems with identical boilers
6.3 The seasonal efficiency of the boiler should be determined using equation 6.1.
boiler seasonal efficiency = 0.81η30% + 0.19η100%
Where:
η30% is the gross boiler efficiency measured at 30% load
η100% is the gross boiler efficiency measured at 100% load.
NOTE: Efficiencies based on net calorific value should be converted to efficiencies based on gross calorific value, using the appropriate conversion factor in the Standard Assessment Procedure version 10 Table E4. Equation 6.1 assumes that the efficiency at 15% load is the same as that at 30% load.
6.4 Equation 6.1 applies to both of the following.
a. Single-boiler systems that:
i. produce low temperature hot water
ii. have an output of less than or equal to 400kW.
b. Multiple-boiler systems that:
i. produce low temperature hot water
ii. comprise individual boilers with identical efficiencies
iii. have an output of less than or equal to 400kW.
NOTE: For boilers with an output of more than 400kW, the manufacturer’s declared efficiencies should be used.
Multiple-boiler systems in new buildings
6.5 For multiple boilers in new buildings, the four-step method described below should be used to calculate the overall boiler seasonal efficiency.
a. Step 1: Determine the load on each boiler for each of the three system part load conditions of 15%, 30% and 100%.
NOTE: For example, if the total system output is made up of three equally sized boilers, at 15% of system output the lead boiler will be operating at 45% of its rated output with the other two boilers switched off.
b. Step 2: Determine the efficiency of each boiler for the above operating conditions.
NOTE: Linear interpolation should be used to determine efficiencies between manufacturers’ declared efficiencies at 30% and 100% load. If efficiencies at below 30% are required and unavailable, the boiler efficiency may be taken as equal to that at 30% load.
c. Step 3: Calculate the overall operating efficiency at each system part load condition using equation 6.2.
ηp = Qp/Σ(qb,p/ηb,p)
Where:
ηp is the system efficiency at part load condition p, i.e. 15%, 30% and 100% of system rated output
Qp is the system heat output at part load condition p
qb,p is the individual boiler heat output at system part load condition p
ηb,p is the individual boiler efficiency at system part load condition p.
d. Step 4: Calculate the overall boiler seasonal efficiency (ηOBSE) as the weighted average of the efficiencies at the three load conditions, using equation 6.3.
ηOBSE = 0.36η15% + 0.45η30% + 0.19η100%
Multiple-boiler systems with non-identical boilers replacing existing systems
6.6 In existing systems, equation 6.4 should be used to calculate the overall boiler seasonal efficiency if both of the following apply.
a. More than one boiler is installed on the same heating system.
b. The efficiencies of the boilers are not identical.
NOTE: All boilers should be used in the calculation, including any that are identical.
ηOBSE = Σ(ηBSE × R)/Σ R
Where:
ηOBSE is the gross overall boiler seasonal efficiency – an average, weighted by boiler output, of the individual seasonal boiler efficiencies.
ηBSE is the gross boiler seasonal efficiency of each individual boiler calculated using equation 6.1
R is the rated output in kW of each individual boiler (at 80/60°C flow/return temperature).
Boiler controls
6.7 Boiler systems with an output of more than 100kW should have both of the following.
a. Optimum start/stop control with either:
i. night setback
ii. frost protection outside occupied periods.
b. Either:
i. two-stage high/low firing facility in boiler
ii. multiple boilers with sequence control to provide efficient part-load performance.
6.8 Gas-fired boilers and multi-stage oil-fired boilers with an output of more than 500kW should have fully modulating burner controls.
Biomass boilers
6.9 The efficiency of biomass boilers at their nominal load and tested to BS EN 12809 should be no lower than the following.
a. For independent gravity-fed boilers of ‹20.5kW output: 65%.
b. For independent automatic pellet/woodchip boilers: 75%.
Gas and oil-fired warm air heaters
6.10 In addition to meeting the general requirements for heating systems in Section 5, warm air systems in new and existing buildings should meet the heat generator seasonal efficiency in Table 6.3.
Table 6.3 Minimum heat generator seasonal efficiency for gas and oil-fired warm air heaters
Gas and oil-fired radiant heaters
6.11 In addition to meeting the general requirements for heating systems in Section 5, radiant heaters in new and existing buildings should meet the heat generator seasonal efficiency in Table 6.4.
6.12 For flued appliances, thermal efficiency should be measured to either of the following test standards, as applicable:
a. BS EN 1020
b. BS EN 13842.
The calculation of the thermal efficiency (net calorific value) should both:
a. exclude fans
b. take account of the radiant heater and associated flue pipe/tailpipe within the building envelope.
Table 6.4 Minimum performance standards for radiant heaters
Electric space heating systems
NOTE: Electric resistance heating is assumed to be 100% efficient, therefore no minimum efficiency is set for these types of system.
NOTE: This section of the guidance does not cover either of the following.
a. Electric heat pumps (guidance is provided in paragraphs 6.44 to 6.46).
b. Portable electric heating devices.
6.13 Electric space heating systems should meet the guidance in paragraphs 6.14 to 6.19, in addition to the general requirements for heating systems in Section 5.
6.14 Electric boiler systems should comply with all of the following.
a. Systems should both:
i. have flow temperature control
ii. be capable of modulating the power input to the primary water depending on space heating conditions.
b. Timing and temperature demand control should be provided.
c. If the building has a floor area greater than 150m2, heating should be split into different heating zones and each zone should have separate controls for timing and temperature demand.
6.15 Electric warm air systems should comply with both of the following.
a. Have timing and temperature demand control provided.
b. If the building has a floor area greater than 150m2, heating should be split into different heating zones and each zone should have separate controls for timing and temperature demand.
6.16 Electric radiant heaters should have automatic zone or occupancy control through presence detection.
6.17 Electric panel or skirting heaters should have controls for timing and temperature demand.
6.18 The input charge for electric storage heaters should be adjusted automatically, based on the internal air temperature. Manual control of heat release from the appliance should be possible.
6.19 Electric fan convectors should have switching to control both of the following.
a. The local fan.
b. The temperature of individual fan convectors.
Combined heat and power
NOTE: This section of the guidance covers CHP systems that both:
a. have a total power capacity between 5kWe and 5MWe
b. are used in commercial applications.
For systems with a total power capacity less than 5kWe, follow the guidance in Approved Document L, Volume 1: Dwellings.
6.20 CHP plant should, under annual operation, have both of the following.
a. A minimum CHPQA quality index (QI) of 105.
b. Power efficiency greater than 20%.
6.21 CHP plant should have a control system that, as a minimum, ensures that the CHP unit operates as the lead heat generator. Metering should be provided that measures all of the following.
a. Hours run.
b. Electricity generated.
c. Fuel supplied to the CHP unit.
Dedicated domestic hot water heaters
6.22 The recommended minimum standards set out in this section apply only to dedicated water heaters. Central heating boilers which provide space heating and domestic hot water should meet the minimum standards in paragraphs 6.2 to 6.9. Heat pumps which provide domestic hot water should meet the minimum standards in paragraphs 6.44 to 6.46.
6.23 In addition to meeting the general requirements for heating systems in Section 5, domestic hot water systems in new and existing buildings should meet the minimum thermal efficiencies in Table 6.5. Thermal efficiency should include the heat generator and any integral storage vessel, but exclude the following, where present.
a. Secondary pipework.
b. Fans and pumps.
c. Diverter valves, solenoids, actuators.
d. Supplementary storage vessels.
6.24 Domestic hot water systems should be sized for the anticipated domestic hot water demand of the building, based on BS EN 12831-3. Systems should not be significantly oversized.
Table 6.5 Minimum thermal efficiencies for domestic hot water (DHW) systems
6.25 Where efficiency data is not readily available, efficiencies should be calculated using manufacturers’ recovery rates and equations 6.5 and 6.6.
equations 6.5:
gross thermal efficiency = heater output / gross input
equations 6.6:
heater output = recovery rate of heater in litres/second × specific heat capacity of water × temperature rise of water
Controls for combustion-heated domestic hot water systems
6.26 Domestic hot water systems should have both of the following.
a. Time control which is independent of space heating circuits.
b. Electronic temperature control.
6.27 Primary hot water circuits for domestic hot water or heating should have fully pumped circulation where this is compatible with the heat generator.
6.28 Direct-fired circulator systems, direct-fired storage systems and indirect-fired circulator systems should have automatic thermostatic control to do both of the following.
a. Shut off the burner/primary heat supply when the desired water temperature is reached.
b. Shut off primary flow if the system temperature is too high.
6.29 Direct-fired continuous flow systems should include both of the following.
a. A flow sensor to control the rate of flow through the heat exchanger. This should both:
i. control outlet temperatures
ii. if the sensor detects insufficient flow, shut off the burner/heat input.
b. A high limit thermostat to shut off the primary flow if the system temperature is too high.
Controls for electrically heated domestic hot water systems
6.30 Point-of-use, local and centralised electrically heated domestic hot water systems should have automatic thermostatic control to interrupt the electrical supply when either of the following occurs.
a. The setpoint storage temperature is reached.
b. The system temperature gets too high.
Manual reset should be possible if there is an over-temperature trip.
6.31 Local and centralised electrically heated domestic hot water systems should have both of the following.
a. Seven-day time control.
b. The facility to boost the temperature by using an immersion heater in the cylinder.
6.32 Water heaters in instantaneous electrically heated domestic hot water systems should include both of the following.
a. A flow sensor to control the rate of flow through the heat exchanger. If the sensor detects insufficient flow, it should shut off the electrical input.
b. A high limit thermostat to shut off the primary flow if the system temperature is too high.
Comfort cooling
NOTE: Evaporative cooling and desiccant cooling systems are not within the scope of this guidance.
6.33 In addition to meeting the general requirements for cooling systems in Section 5, the seasonal energy efficiency ratio (SEER) of each cooling unit should meet the minimum standards in Table 6.6.
6.34 The specification of comfort cooling systems should be based on an appropriate heat gain calculation for the building, based on CIBSE’s Guide A. Systems should not be significantly oversized. In most circumstances this means that the cooling appliance should not be sized for more than 120% of the design cooling load.
Table 6.6 Minimum seasonal energy efficiency ratio (SEER)(1) for comfort cooling
Controls
6.35 Comfort cooling/air-conditioning systems should have all of the following controls.
a. The systems should be subdivided into separate control zones for areas of the building for which any of the following are significantly different.
i. Solar exposure.
ii. Pattern of use.
iii. Type of use.
b. For each control zone and for each terminal unit, it should be possible to control both of the following (independent of other control zones).
i. Timing.
ii. Temperature.
c. If both heating and cooling are provided in the same space, the controls should prevent them operating simultaneously.
d. Multiple cooling units should be provided with controls that ensure that the combined plant operates in its most efficient modes. Central plant should operate only when the zone systemsrequire it. The default condition should be off.
e. Controls for comfort cooling systems should meet BS EN 15232 Band C.
f. Controls should meet the requirements for thermostatic room controls in paragraphs 5.14 to 5.16.
Calculating the seasonal energy efficiency ratio
6.36 The value of the seasonal energy efficiency ratio (SEER) and the seasonal coefficient of performance (SCOP) should be determined using BS EN 14825 with average climate data; in conjunction with the Ecodesign Commission Regulation No. 2016/2281. The SEER of the cooling unit is given by equation 6.7.
equation 6.7:
SEER = a(EER100%) + b(EER75%) + c(EER50%) + d(EER25%)
Where:
EERx is the EER measured at the load conditions of 100%, 75%, 50% and 25% at the operating conditions detailed for the part load energy efficiency ratio.
a, b, c and d are the load profile weighting factors relevant to the proposed application. The load profile weighting factors can be taken from either of the following.
a. Table 6.7, if appropriate.
b. A detailed simulation or prediction of the load profile of the building. The calculation should include the desired indoor condition as well as the ambient loads in which the system will work.
Table 6.7 Standard cooling load factors for office accommodation
6.37 For cooling units for which there is no part load data, the SEER is the full load EER.
For applications where the load profile is not known but there is some data on chiller part load EER, the following apply.
a. For chillers where the full and half load (50%) EERs are known: the SEER is the average of the full load and half load EERs.
b. For chillers with four points of part load EER: the SEER is calculated using equation 6.7 with each EER weighted equally.
c. If the chiller used does not have data for four steps of load: the weights are apportioned appropriately.
6.38 For plants with multiple chillers, a plant seasonal energy efficiency ratio (SEER) should be calculated based on the sum of the energy consumption of all the operating chillers. All the following factors should be included.
a. Degree of oversizing of the total installed capacity.
b. Sizes of individual chillers.
c. EERs of individual chillers in operating conditions.
d. Control mode used, e.g. parallel, sequential, dedicated low load unit.
e. Load profile of the proposed building.
f. Building location (which determines ambient conditions).
6.39 For systems that have the ability to use free cooling or heat recovery, the SEER should be derived for the specific application, including free cooling or heat recovery elements. For variable refrigerant flow (VRF) systems, any calculations must include indoor and outdoor conditions, the power input from controls, and indoor units.
6.40 For absorption chillers used in conjunction with on-site CHP or a district heat network or community heating system, the CO2 emissions and primary energy should be calculated in the same way as when using CHP for heating. The control system should ensure as far as possible that heat from boilers is not used to supply the absorption chiller. The minimum full load EER of the absorption chillers should be no worse than 0.7.
6.41 For district cooling schemes, the CO2 and primary energy content of the cooling energy supplied should be calculated. This value should be used to calculate the building emission rate and primary energy rate.
Heating and cooling system circulators and water pumps
6.42 On variable volume systems, variable speed glandless circulators should be used.
6.43 If a water pump is used on a closed loop circuit and the motor is rated at more than 750W, then it should be fitted with or controlled by an appropriate variable speed controller on any variable volume system.
Heat pumps
6.44 Air-to-air heat pumps with an output of 12kW or less should have either of the following.
a. A seasonal coefficient of performance (SCOP) rating for the median temperature range in BS EN 14825 of at least D.
b. A coefficient of performance (COP) that is not less than the value in Table 6.8.
Table 6.8 Minimum COP for heat pumps in new and existing buildings
6.45 In addition to the general guidance for zoning and controls in Section 5, any outdoor fans, including those in cooling towers or dry coolers, should be controlled.
6.46 For heat pump installations in which there are other heat sources available to the same building, each of these heat sources should be appropriately incorporated into a singular control system.
Mechanical ventilation
6.47 The specification of ventilation systems should be based on the ventilation needs of the building, in accordance with Approved Document F, Volume 2: Buildings other than dwellings.
6.48 Air handling systems should be capable of achieving a specific fan power (SFP) at 25% of design flow rate no greater than the SFP achieved at 100% design flow rate.
6.49 Fans used for general air distribution that are rated at more than 1100W should be fitted with variable speed drives.
6.50 Ventilation ductwork should be made and assembled so as to be reasonably airtight. Ductwork should comply with the specifications in either of the following.
a. BESA’s DW/144.
b. BS EN 1507, BS EN 12237 and BS EN 13403.
6.51 Air handling units should be made and assembled so as to be reasonably airtight. Air handling units should comply with Class L2 air leakage given in BS EN 1886.
6.52 The specific fan power of air distribution systems at the design air flow rate should be no greater than in Table 6.9, as adjusted by the appropriate factors within this table.
Specific fan power should be calculated in accordance with BS EN 16798-3 at the full design load. For fan coil units, use BS 8850.
Table 6.9 Maximum specific fan power (SFP) in air distribution systems in new and existing buildings
Controls
6.53 Mechanical ventilation systems should have all of the following.
a. The systems should be subdivided into separate control zones for areas of the building for which any of the following are significantly different.
i. Solar exposure.
ii. Pattern of use.
iii. Type of use.
b. For each control zone it should be possible to control all of the following (independent of other control zones).
i. Timing
ii. Where appropriate, temperature.
iii. Where appropriate, ventilation rate.
iv. Where appropriate, air recirculation rate.
c. Central plant should operate only when the zone systems require it. The default condition should be off.
6.54 System controls should be wired so that when there is no demand for space heating or hot water, the heating appliance, if appropriate, and pump are switched off.
6.55 Central mechanical ventilation systems should have both of the following.
a. Time control at room level.
b. On/off time control at air handler level.
6.56 Heat exchangers should have both of the following.
a. Defrost control to protect the heat exchanger.
b. Control to ensure that heat recovery can be stopped, modulated or bypassed during periods when heat recovery is undesirable.
Supply temperature control should be provided via a variable set point with outdoor temperature compensation.
6.57 Local and zonal systems should have on/off air flow control at room level.
Heat recovery
6.58 Ventilation systems that provide supply and extract ventilation should be fitted with a heat recovery system where technically feasible.
Lighting
6.59 Any fixed lighting should achieve levels of illumination appropriate to the activity in the space.
Spaces should not be over-illuminated. Lighting should be designed based on CIBSE’s SLL Lighting Handbook or an equivalent design guide.
NOTE: For smaller spaces where total lighting power is likely to be low (toilets, store rooms etc.) there is no expectation that lighting calculations should be produced.
6.60 Lighting should observe the following.
a. If it is general lighting, either:
i. have an average luminaire efficacy of 95 luminaire lumens per circuit-watt
ii. the Lighting Energy Numeric Indicator (LENI) method, following Appendix B.
b. If it is display lighting, any of the following:
i. have an average light source efficacy of 80 light source lumens per circuit-watt
ii. have a rated power usage no greater than 0.3W/m2 in each space
iii. the LENI method, following Appendix B.
c. For high excitation purity light sources, an average light source efficacy of 65 light source lumens per circuit-watt.
NOTE: This approved document does not include minimum standards for specialist lighting, such as theatrical spotlights, stage lighting, gobo projectors or wall-washers.
6.61 General lighting and display lighting should be metered by one of the following methods.
a. Dedicated lighting circuits with a kWh meter for each circuit.
b. Local power meter coupled to or integrated in the lighting controllers of a lighting management system.
c. A lighting management system that can both:
i. calculate the consumed energy
ii. make this information available to a building management system.
Lighting controls
6.62 Lighting controls in new and existing buildings should follow the guidance in the Building Research Establishment’s Digest 498.
6.63 Unoccupied spaces should have automatic controls to turn the general lighting off when the space is not in use (e.g. through presence detection). Occupied spaces should have automatic controls where suitable for the use of the space.
6.64 General lighting in occupied spaces should have daylight controls (e.g. photo-switching and dimming) for parts of the space which are likely to receive high levels of natural light.
6.65 Display lighting should be controlled on dedicated circuits that can be switched separately from those for lighting provided for general illuminance.
Building automation and control systems
6.66 If a new building has a space heating or air-conditioning system with an effective rated output greater than 180kW, a building automation and control system should be installed.
6.67 If an existing building has a space heating or air-conditioning system with an effective rated output greater than 180kW, a building automation and control system being replaced or installed should follow paragraphs 6.72 and 6.73.
NOTE: The requirements in paragraphs 6.66 and 6.67 also apply to buildings containing heating and air-conditioning systems which are combined with ventilation systems.
6.68 For building systems that do not satisfy paragraph 6.66 or 6.67, consideration should be given to providing centralised controls to allow the facilities manager to switch off appliances when they are not needed. Where appropriate, these should be automated (with manual override) so that energy savings are maximised. Consideration should be given to the power requirements of essential (e.g. life safety) systems.
Determining the effective rated output
6.69 The effective rated output of a space heating or air conditioning system is the combined output of the equipment in the building which is provided for heating or cooling the internal space in normal operation, for the comfort of occupants.
For air-conditioning systems, the effective rated output should include the combined maximum output of both of the following, as specified by the manufacturer.
a. Air-conditioning systems.
b. Air-conditioning systems combined with or as part of a ventilation system.
For heating systems, the effective rated output should include the combined maximum output of all the following, as specified by the manufacturer.
a. Primary space heating systems.
b. Space heating systems combined with or as par t of a ventilation system.
c. Secondary space heating systems.
It does not include any of the following.
d. Heating or cooling equipment only intended for emergency or occasional backup use.
e. Heating equipment for frost protection.
f. Heating for domestic hot water.
g. Heating or cooling for industrial processes.
6.70 If the building is heated through a district heat network or community heating system, the effective rated output should be based on the capacity of the equipment installed in the building, making reasonable assumptions for the operation of the district heat network or community heating system, including flow temperatures.
6.71 The effective rated output should be assessed based on the final installed capacity of the heating or air-conditioning system. When estimating the effective rated output at the design stage, designers should make allowances for the final installed capacity, including potential oversizing and equipment substitution.
Building automation and control system specification
6.72 A building automation and control system installed in a new or existing building, where the building meets the space heating or cooling criteria in paragraphs 6.66 and 6.67, should be capable of carrying out all of the following functions.
a. Fully complies with BS EN ISO 16484.
b. Continuously monitors, logs, analyses and allows for adjusting energy use.
c. Benchmarks the building’s energy efficiency, detects losses in efficiency of heating, ventilation and air conditioning systems, and informs the person responsible for the facilities or building management about opportunities for energy efficiency improvement.
d. Allows communication with connected fixed building services and other appliances inside the building and is interoperable with fixed building services across different types of proprietary technologies, devices and manufacturers.
NOTE: A BS EN 15232 Class A rated type system would meet these requirements.
6.73 Where a building automation and control system is installed, its control capabilities should be appropriate for the building, its expected usage and the building services specification.
On-site electricity generation and storage
6.74 Where on-site electricity generation and storage is installed, such as photovoltaic panels or battery storage, systems should be an appropriate size for the site, available infrastructure and on-site energy demand.
6.75 The system should be specified and installed according to the manufacturer’s instructions to ensure the overall performance of the system meets a reasonable standard.
6.76 When replacing an existing system, the installed generation capacity of the new system should be no less than that of the existing system, except where a smaller system can be demonstrated to be more appropriate or effective (e.g. replacing an existing system with a system which is better matched to the building’s energy demand).
6.77 On-site electricity generation should be provided with automated controls that support the design of the system and the intended use. This is particularly the case where electricity generation and storage systems are used, such as batteries.
District heat networks and community heating
6.78 The central heat source for community heating systems should comply with the relevant minimum standards outlined throughout Section 6 of this approved document.
6.79 A district heat network that is being connected to a new building should not have either of the following.
a. A CO2 emission factor for delivered heat to the building greater than 0.350kgCO2/kWh.
b. A primary energy factor for delivered heat to the building greater than 1.450kWhPE/kWh.
NOTE: The same CO2 emission factors and primary energy factors used to calculate the building emission rate and building primary energy rate described in paragraph 2.7 of this approved document should be used to check against the minimum performance standards described in paragraph 6.79.
