Regulations

Part L: Conservation of energy

In April 2006, a greatly revised version of Part L of the Building Regulations came into force. As well as being stricter, it was split into four parts: L1A covering new homes, L1B covering existing ones and the other two covering non-dwellings.

The most significant change to the previous version of Part L is the approach taken to compliance. Designs must use the whole-building carbon emissions methodology. Previously, the elemental method allowed designers to consider the thermal performance of each part of the building separately. For dwellings, measurements must be done using the government’s standard assessment procedure, or SAP 2005.

A building that complies with the 2006 revision of Part L will be about 25% more efficient than one meeting the 2002 standard. The next reform, expected in 2010, will impose a further 25% reduction in CO2 emissions, which equates to level three of the Code for Sustainable Homes (see below). This is already a requirement when building for English Partnerships and housing associations.

The new regulations have led to a much greater uptake of items such as whole-house mechanical ventilation with heat recovery systems, and it is worth noting that this might have implications for maintenance. There is also a greater emphasis on airtightness – the minimum target is now 10 m3/h/m2. Typically, between 5 and 7 is being achieved, although consistency is a problem.

Beyond 2010, the government aims to use the Building Regulations to cut energy use. In 2013, there will be a 44% reduction and in 2016 all new homes will be zero carbon.

Part F: Ventilation

When Part L was revised, Part F was also given an overhaul. This involved a shift from prescriptive regulations to performance-based compliance, giving designers more scope for innovation.

There are now three approaches to ventilating a dwelling. The first is to follow the guidance on acceptable levels of moisture in the air to avoid mould growth and indoor pollutants. The second is to meet specified supply and extract rates in the approved document. The third is to follow the detailed design guidance for a range of ventilation systems.

Guidance on the ventilation of basements was also provided for the first time.

The new regulations have led to a much greater uptake of items such as whole-house mechanical ventilation with heat
recovery systems

Part B: Fire safety

In April a revised version of Part B came into force. This had a big impact on the non-domestic sector but also affected buildings such as tall residential blocks.

Apartment buildings more than 30m high must now have sprinklers. The way in which common areas are to be kept free from smoke during fire has also changed. Now, mechanical ventilation is required where there are no smoke shafts or automatic opening vents.

Recognising that there is no control of individual flats once they are occupied, the need to provide self-closing devices for fire doors within flats has been removed.

The Code for Sustainable Homes

Since April this year, developers of new homes in England have been able to choose to have their homes assessed against the Code for Sustainable Homes. This is the standard for the design and construction of homes, under which structures are given between one and six stars.

The code sets minimum standards for energy, water and materials use, surface water management and site waste management. In England it has replaced the EcoHomes scheme developed by BRE.

All its energy performance requirements are higher than the Building Regulations. Level one of the code requires a 10% improvement on energy performance over 2006 Part L, while level six equates to a zero-carbon home.

The code is voluntary (except for social landlords) but a consultation on making it mandatory closed this October.