Legislation

Building regulations

Building Regulations are made under the Building Act 1984. Part L of Building Regulations addresses conservation of fuel and power.

This building regulation is a legal requirement and is split into four parts:

• L1A– New dwellings
• L1B – Existing dwellings
• L2A – New building other than dwellings
• L2B – Existing building other than dwellings

Part L sets maximum carbon dioxide emission targets and provides guidance on thermal efficiency of fabrics and air permeability limitation within building design.

L2A – New buildings other than dwellings

Part L2A covers the following:

• Achieving an acceptable CO₂ emission rate
• Limiting air permeability
• Minimum values of thermal conductivity efficiency (U-value) for building materials
• Splitting controls for heating, ventilation and air conditioning systems into zones
• Specifying suitably efficient plant
• Installing insulation to the Non Domestic Heating, Cooling and Ventilation Compliance Guide
• Installing energy meters to enable at least 90% of energy use to be assigned to end use, with automatic meter reading and data collection for buildings over 1000 sq.m
• Limiting effects of solar gain
• Lighting efficiency of not less than 45 luminaries-lumens/circuit-Watts, as averaged over the whole area and providing adequate control to avoid unnecessary use

Note: Achieving an acceptable building CO₂ emission rate is calculated by achieving a percentage reduction of CO₂ emission rate compared to a notional building built to the 2002 regulations. This is typically 25% and is dependent on whether building is naturally ventilated or mechanically air conditioned.

L2B – Existing buildings other than dwellings

This part is for refurbishments of over 1000 sq.m of usable floor area (note large extensions are considered as new buildings). Part L2B includes the following points:

• Achieving an acceptable CO₂ emission rate
• Limiting the air permeability and pressure testing
• Quality of commissioning
• Minimum values of thermal conductivity efficiency (U-value) for building materials
• Splitting controls for new heating, ventilation and air conditioning systems into zones
• Specifying suitably efficient plant
• Installing energy meters to enable at least 90% of energy use to be assigned to end use
• Upgrading lighting with less than 40 luminaries-lumens/circuit-Watts
• Lighting efficiency of not less than 45 luminaries-lumens/circuit-Watts, as averaged over the whole area and providing adequate control to avoid unnecessary use