Thermal Regulations
Approved Document L - Edition 2006
(ADL) Conservation of Fuel and Power

Objectives of Part L
Approved Document L 2006 sets out to make buildings more energy efficient, with an aim to reduce carbon production by one million tons per year.

Methods of compliance

The new ADL offers only one method of compliance, based on the whole building
energy performance approach. All new buildings MUST now achieve a minimum
CO2 emissions rate based on the following methodologies:

ADL1A - SAP 2005 (SAP worksheet and specification can be downloaded from www.bre.co.uk/sap

ADL2A - NCM /SBEM (Simplified Building Energy Model). Further information can be downloaded from www.ncm.bre.co.uk

New dwellings - Demonstrating compliance

Compliance with L1A is demonstrated by meeting five criteria:
1. The Dwelling Emission Rate (DER) is no greater than the Target CO2 Emission rate.
2. The performance of the as built dwelling is consistent with the DER.
3. Provisions are put in place to ensure the energy efficiency of the dwelling.
4. The buildings fabric and fixed services perform no worse than set design limits.
5. Appropriate passive control measures are put in place to limit the effect of solar gain on the dwelling.

Achieving the TER
Using SAP, calculate the CO2 emission rate of a notional building (Table 1) based on the same size and shape as the proposed dwelling, using a fixed set of criteria for the fabric heat loss, fuel choice and building services. The resulting CO2 emissions rate is then equivalent to a gas heated dwelling insulated to ADL 2002 standards.

Table 1: U-values used in the notional dwelling

The TER is arrived by reducing the notional buildings CO2 emission rate by 20% and making an allowance for any changes in the main heating fuel using the fuel factor (Table 2).

Table 2: Fuel Factor

The SAP calculation is then repeated but this time inserting the proposed fuels, building services, U-values and low or zero carbon energy sources for the proposed dwelling. This produces the Dwelling Carbon Rate (DER). If the DER is less than the TER the first set of criteria has been achieved.

Limit on design flexibility
It must be shown that the thermal performance of the dwelling fabric, lighting systems, heating and hot water systems are within the design limits.

Limiting solar gain in summer
To prevent high internal temperatures due to solar gain, designers should use Appendix P of SAP 2005 to calculate the level of risk.

Quality of construction and commissioning
The building insulation envelope should be constructed in such a way as to avoid where possible thermal bridging. Recognised design details should be adopted and to ensure quality of construction an air pressure test should be carried out by an accredited tester.

Exceptions include:
• Buildings with a floor area less than 500m2.
• Factory made modular buildings.
• Large complex buildings.
Refer to ADL2A for further information.