The GLA’s Energy Assessment Guidance (2022) introduced an Energy Use Intensity (EUI) target of 35 kWh/m2.yr for residential developments. To meet this target, the following budget is proposed.
The points outlined below provide ideas on how the 35 kWh/m2.yr EUI target could be achieved.
- Fabric performance – minimising thermal bridging, low u-values.
- Heat pumps should be specified because the use of gas boilers significantly increases the energy associated with space heating.
- The specification of mechanical ventilation heat recovery (MVHR) instead of natural ventilation, or mechanical extract ventilation (MEV) reduces annual space heating demand due to the heat recovery and lower air permeability (i.e. <3m3/m2.hr).
- Individual systems perform better than heat networks due to lower distribution losses.
- Specification of waste water heat recovery – ideally System B (showers only).
- Reduced storage losses from HIU and hot water cylinders. For individual heat pumps, this could be further improved by selecting a heat pump with a large heat exchanger transfer area within the hot water cylinder.
- Heat pumps should be specified because the use of gas boilers significantly increases the energy associated with hot water.
- While fixed electricals (pumps, fans, and lighting) only make up a small proportion of energy use, these are higher when connected to a heat network.
- Unregulated energy accounts for cooking and appliances. There is no set methodology to determine unregulated energy use, therefore it is difficult to quantify how to reduce unregulated energy demands. One way that unregulated emissions can be minimised is by specifying A-rated appliances.