Part L2 (Conservation of fuel and power in non-domestic dwellings)

Building Regulations Part L2 (Conservation of fuel and power in non-domestic dwellings) Effective from October 2010

The new Part L2 Part A for new buildings and Part B for work on existing buildings came into force in October 2010.

To fall in line with the EU Energy Performance in Building Directive (EPDB), the new L2 2010, Part F (Northern Ireland - update due 2012) and the Technical Handbook – Section 6 (Scotland) 2011 documents require a major change in the way buildings are to be assessed for compliance with energy efficiency and carbon emission standards.

The new approach taken is to compare the CO2 emissions for the actual building (Building Emission rate-BER) with those if a National Calculation Methodology (NCM) – the approved procedure for demonstrating compliance with the UK building regulations – (Target Emission Rate – TER).

This approach has been adopted because of the variations in improvement potential across a variety of building types. Extensive research was carried out into the main building categories, and appropriate levels of CO2 emissions reduction over 2006 emissions rates is 25%.

Part L requires a reasonable provision for the conservation of fuel and power in buildings by:

a. Limiting heat gain and losses:

i Through thermal elements and other parts of the building fabric and;

ii From pipes, ducts and vessels used for space heating and space cooling and hot water services:

b. Providing and commissioning energy efficient fixed building services that are fitted with effective controls and;

c. Providing the building owner with sufficient information about the building and the fixed building services and their maintenance requirements, to allow their efficient operation.

Approved Documents offer technical guidance on means of compliance with the building regulations. They are not intended to represent the only methods available, but they do provide reference points that are useful in the practical process of compliance. If the guidance is followed, there is a presumption that the compliance requirements will be met.

Approved Document Part LA2 cover work on new non-domestic buildings and major extensions to existing non-domestic building – i.e. where the additional useful floor area is greater than 100m2 and 25% of the original building’s floor area.

The new regulations require the submission of a checklist that demonstrates that compliance has been met against five defined criteria. These criteria are detailed in Approved Document L2A.

Criteria 1 mandatory and refer directly to building regulation 17C. Criteria 2-5 are considered as guidance.

Criteria Main Points

  1. The building emission rate (BER) must be less than the target emission rate (TER) as calculated under the approved methodology.
  2. The performance of the building fabric and heating hot water and fixed lighting systems should achieve reasonable overall standards of energy efficiency. To avoid a situation where poorly performing systems or construction details are compensated for by other building fabric and services. For building services, this includes the use of appropriate controls, equipment with minimum efficiency levels (verified by testing to acceptable standards) see “Associated Documents” below and appropriate levels of metering and monitoring.
  3. The building shall be provided with appropriate passive control measures to limit solar gains – to reduce the need for, or capacity of air conditioning systems. (Note that compliance with the suggested assessment method does not imply that acceptable levels of comfort will be achieved in the space.
  4. The performance of the building, as built, is consistent with the BER. Credits are given in the emissions calculation procedures where this can be demonstrated. Particular attention is required to building air-tightness, where extensive guidance exists and to the continuity of thermal insulation, for which it is suggested that reference be made to accredited construction details and third party verification of design detail. Building services are required to be commissioned effectively (where possible) according to the approved procedures in CIBSE guide M – Commissioning Management. Documentary evidence of the use of the approved procedure is required for Building Control to issue a final compliance certificate. Air leakage testing of ductwork may be required, depending on the classification claimed in the BER calculation.
  5. The necessary provisions for energy-efficient operation of the building are put in place. This is best achieved by using the guidance in CIBSE TM31 – Building Log Book toolkit. Information on the building services equipment may be cross referenced to the specification documentation and the manufacturers’ operation and maintenance manuals. Data used to calculate the TER and BER should be included in the Log Book along with the recommendations for improvements that are generated by the assessment software package used.