Energy Conservation

The Building Regulations (Approved Document Part L1A: Conservation of fuel and power in new dwellings [2006 edition]) require that all new dwellings have predicted carbon dioxide emissions - Dwelling Emission Rate (DER) - not greater than the Target Emission Rate (TER) determined for the equivalent notional building of the same size and shape. The TER, expressed as the quantity of CO2 in kg emitted per m2 of floor area per year, is calculated for dwellings of less than or equal to 450 m2 total floor area by the Standard Assessment Procedure (SAP 2005 edition). For all dwellings above 450 m2 floor area, the Simplified Building Energy Model (SBEM) calculation is required. For reasons of energy conservation and climate change, the target emissions are reduced to 80% of those from equivalent buildings compliant to the previous 2002 regulations.

The following reference figures are area-weighted average limits for guidance. However, for most buildings enhanced specifications are likely to be required in order to achieve the required carbon dioxide Target Emission Rate.

Floor 0.25 W/m2 K

Windows/roof window/door 2.2 W/m2 K

U-values better than the following are considered to be positive design features:

Wall

Floor

Roof

Window/door

The Building Regulations also require provision to prevent excessive summer solar gains causing high internal temperatures. This can be achieved by the appropriate use of window size and orientation, solar control with shading or specialist glazing systems, ventilation and high thermal capacity. The Building Regulations set limits on services performance and envelope airtightness (including sample pressure testing) and in addition they require each new building to be supplied with guidance on its energy efficient operation.

The TER method gives a good degree of flexibility in relation to the design by allowing trade-offs between different energy-saving factors. The benefits of useful solar radiation gains may also be taken into account.

The Building Regulations (Approved Document Part L2A: Conservation of fuel and power in new buildings other than dwellings [2006 edition]) requires the predicted carbon dioxide emissions - Building Emission Rate (BER) to be no greater than the Target Emission

Rate (TER) calculated by the Simplified Building Energy Model (SBEM) or other approved software tools. The area-weighted average limits for elements are set at the same standards as for new dwellings. However, the appropriate Building Emission Rate, rather than individual element U-values, is required for compliance.

Building Regulations Approved Documents Part L1B and L2B refer to work on existing dwellings and other buildings respectively. Guidance is quoted on the reasonable provision and standards for new extensions and replacement of existing thermal elements, but again, full compliance in all aspects of the regulations is required.

Standards for new elements in existing buildings:

Wall Floor

Pitched roof - insulation at ceiling level Pitched roof - insulation at rafter level

Flat roof - integral insulation Windows/roof window/ roof light

0.20 W/m2 K 1.8 W/m2 K or Band D or centre pane 1.2 W/m2 K

Standards for replacement elements in existing buildings:

Wall Floor

Pitched roof -insulation at ceiling level Pitched roof -insulation at rafter level Flat roof - integral insulation Windows/roof window/roof light

2.0 W/m2 K (dwellings) 2.2 W/m2 K(non dwellings) or Band E or centre pane 1.2 W/m2 K

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