New building services
5.1 For each new fixed building service in a new or existing building, the efficiency of the service should be no lower than the value set out in Section 6. If a proposed service is not covered in Section 6, the service should be shown to be no less efficient than a comparable service that is covered.
5.2 Both of the following apply to the efficiency claimed for a fixed building service.
a. The efficiency should be based on the appropriate test standard set out in Section 5 or Section 6.
b. The test data should be certified by a notified body.
5.3 For heating and cooling systems, paragraphs 5.9 to 5.17 should be followed, in addition to system specific advice in Section 6.
Replacement building services in existing buildings
5.4 A replacement fixed building service should be at least as efficient as the value set out in Section 6 and should comply with either of the following.
a. Use the same fuel as the service being replaced and have an efficiency that is not worse than that of the service being replaced.
b. Use a different fuel than the service being replaced. The system should both:
i. not produce more CO2 emissions per kWh of heat than the appliance being replaced
ii. not have a higher primary energy demand per kWh of heat than the appliance being replaced.
Worked example
Replacing an old oil-fired boiler with emissions of 0.298kgCO2/kWh and primary energy of 1.180kWhPE/kWh at 85% efficiency with an LPG boiler with emissions of 0.241kgCO2/kWh and primary energy of 1.141kWhPE/kWh at 93% efficiency.
CO2 emissions
Oil-fired boiler: 0.298/0.85 = 0.35kgCO2/kWh
LPG boiler: 0.241/0.93 = 0.26kgCO2/kWh
Primary energy
Oil-fired boiler: 1.180/0.85= 1.39kWhPE/kWh
LPG boiler: 1.141/0.93 = 1.23kWhPE/kWh
The new LPG boiler has both lower CO2 emissions and primary energy than the oil-fired boiler being replaced, and therefore complies. It is also at least as efficient as the minimum efficiency as set out in Section 6 of this guidance.
NOTE: For grid-supplied electricity, a CO2 emission factor of 0.136kgCO2/kWh and primary energy factor of 1.501kWhPE/kWh should be used. All other CO2 emission factors and primary energy factors should be taken from Table 29 (or Table 32 for district heat networks) of the National Calculation Methodology Modelling Guide.
NOTE: Where the efficiency of the appliance being replaced is unknown, this should be established in line with the hierarchy outlined in Appendix E.
5.5 If renewable technology such as a wind turbine or photovoltaic array is being replaced, the new system should have an electrical output that is at least the same as that of the original installation.
5.6 When installing a new heating appliance in an existing building, the heating system after the work is complete should have the following controls.
a. Timing.
b. Temperature.
c. Where appropriate and technically feasible, weather compensation.
5.7 For heating systems that are being replaced, paragraphs 5.9 to 5.12 should be followed in addition to system specific guidance in Section 6. Facilitating future connection to any local district heat networks should be considered (e.g. providing capped off connections in pipework to allow later connection to a district heat network).
5.8 If work involves providing or extending fixed building services, energy meters should be installed following paragraph 5.17, and consequential improvements may apply (see Section 12).
Sizing new and replacement space heating systems
5.9 The specification of space heating systems should be based on an appropriate heat loss calculation for the building, based on BS EN 12831-1 and CIBSE’s Guide B1. Systems should not be significantly oversized.
5.10 Where a wet heating system is either:
a. newly installed
b. fully replaced in an existing building, including the heating appliance, emitters and associated pipework all parts of the system, including pipework and emitters, should be sized to allow the space heating system to operate effectively, and in a manner that meets the heating needs of the building, at a maximum flow temperature of 55°C or lower. To maximise the efficiency of these systems, it would be preferable to design to a lower flow temperature than 55°C.
Where it is not feasible to install a space heating system that can operate at this temperature (e.g. where there is insufficient space for larger radiators, or the existing distribution system is provided with higher temperature heat from a low carbon district heat network), the space heating system should be designed to the lowest design temperature possible that will still meet the heating needs of the building.
Controls and zoning for new and replacement space heating systems
5.11 Heating systems should have all the following controls.
a. The systems should be subdivided into separate control zones for areas of the building in 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 both of the following independently of other control zones.
i. Timing.
ii. Temperature.
c. The service should be appropriate to the requirements of the space. If both heating and cooling are provided, the controls should prevent them operating simultaneously.
d. Central plant should operate only when the zone systems require it. The default condition should be off.
e. Where appropriate and technically feasible, heating systems should have weather compensation.
5.12 System controls should be wired so that when there is no demand for space heating, the heating appliance and pump are switched off.
System treatment for hot water systems for space and domestic hot water heating
5.13 Before a new heating appliance is installed, all central heating and primary hot water circuits should be thoroughly cleaned and flushed out. A suitable chemical inhibitor should be added to the primary heating circuit to protect against scale and corrosion. In hard water areas, suitable measures should be taken to treat the feed water to water heaters and the hot water circuit of combination boilers to reduce limescale accumulation.
Thermostatic room controls
5.14 For heating and cooling systems in a new non-domestic building, or when a heat generator such as a boiler is replaced in an existing non-domestic building, each room should be provided with thermostatic room controls. These should be capable of being used to separately adapt the heating or cooling output in each room served by the heating or cooling appliance. Where justified in accordance with paragraph 5.15, heating and cooling may be controlled for each heating zone rather than individual rooms.
NOTE: There is no need to install thermostatic room controls in rooms/zones without heating or cooling in new and existing non-domestic buildings.
NOTE: Installing thermostatic room controls may not be technically feasible in some cases. These may include the following.
a. Buildings with very low heat demand (e.g. less than 10W/m2).
b. Buildings with buffer zones for heat absorption or dissipation with high thermal mass.
5.15 It may be justified to control a heating zone rather than individual rooms in either of the following cases.
a. In open-plan spaces in which heating demand and patterns of use are similar across the whole space, sub-zoning of temperature control might not be appropriate. In such cases, the space should be considered as a single heating zone.
b. Where two adjacent rooms have a similar function and heating or cooling requirements (e.g. kitchen and utility room). In such cases, the adjacent rooms should be considered as a single heating zone.
NOTE: Exhaust air heat pump systems, which extract heat from the exhaust air of a building, may not need to provide independent thermostatic control to individual rooms. Providing room/ zone control on this type of system is unlikely to be economically and/or technically viable.
However, other space heating systems also in use in the same building should be controlled using thermostatic room controls as described above.
5.16 The standards in paragraphs 5.14 and 5.15 may be satisfied by providing any of the following.
a. Both of the following.
i. A thermostat in a room that the heating or cooling circuit serves.
ii. An individual thermostatic room control for each emitter, such as a thermostatic radiator valve, on all emitters outside the room that contains the thermostat. Thermostatic radiator valves should not be used in the same room as the thermostat.
b. An individual room/heating zone thermostat or fan coil thermostat for each room or heating zone.
c. An individual networked heating or cooling emitter control for each emitter.
Energy submeters
5.17 Energy submetering systems should be installed in new buildings, or when fixed building services are provided or extended in an existing building, and should meet all of the following requirements.
a. The various end-use categories, such as heating, lighting and cooling, should be submetered in such a way that at least 90% of the annual energy consumption of each fuel can be assigned to an end-use. Detailed guidance on how to achieve this is given in CIBSE’s TM39.
b. Metering should enable the comparison of forecast energy use and in-performance energy and facilitate energy reporting. This can be demonstrated by basing the submetering strategy on a design-stage energy forecast for the building, using one of the methodologies in paragraph 9.4.
c. Metering should allow the energy use of different tenants within the building to be separately monitored.
d. The outputs of any renewable systems should be separately monitored.
e. In buildings with a total useful floor area greater than 1000m2, automatic meter reading and data collection facilities should be installed.
