A whole alphabet of regulations may be changed soon, as the government aims to tighten up energy efficiency, while not overburdening businesses. It’s already rewritten the definition of zero carbon. Here’s what’s in force and what’s coming up

Already in force

Parl L of the Building Regulations

The latest version of Part L took effect in October 2010 and requires an overall 25% cut in carbon emissions compared with the 2006 version. This applies across the board for dwellings but varies for non-domestic buildings. Called the “aggregate approach”, this recognises it costs more to reduce carbon emissions from some types of buildings than others.

For example, a hotel would need to reduce emissions by about 16%, a supermarket 26% and a shallow plan office 40%. The final reductions will vary according to factors such as size and shape and the type of servicing solution.

Designers are required to put forward a design stage carbon dioxide emission rate and building specification in order to help building control understand the compliance strategy.

For housebuilders, Part L 2010 is the equivalent to the energy component of level 3 of the Code for Sustainable Homes. However, they will find it harder to comply with 2010 Part L than the headline 25% reduction in carbon emissions figures suggests.

Previously, housebuilders could insulate party walls and claim carbon reductions but they will now lose credits if walls are left uninsulated and unsealed. This means reductions will need to be made elsewhere.

Conservatories under 30m2 remain exempt from the requirements, providing the main home heating system isn’t extended into the conservatory and it is separated from the main house by a wall, window or door.

Depending on the solution adopted, compliance costs for homes have increased by 1.67% for apartments, up to 10.3% for mid terrace houses.

Part F of the Building Regulations

This covers ventilation and has been updated with Part L, as airtightness rules in Part L affect indoor air quality. The changes mainly affect homes.

Homes that are more airtight than 5m3/m2/hr at 50pa will require higher ventilation rates to compensate, which in practice means fitting mechanical ventilation and heat recovery systems.

There are new rules on commissioning, and airflow rates for all buildings must be established and submitted to the building control body. Information on ventilation systems must now be given to home occupiers.

Originally intended to set out the road map to zero-carbon homes by 2016, recent changes in policy have rendered the energy elements of the code largely redundant.

Designers have to comply with the energy element of level 3 by default as this is now equivalent to Part L; the code was revised in November 2010 to bring it in line with these changes. Since then, the government has announced that zero carbon now only means mitigating emissions from space and water heating and lighting, taking energy used by appliances out of the definition. The energy element of level 6 will never be part of the Building Regulations unless there is another policy u-turn.

The standards in the code for water use and surface water management, materials, site and household waste still apply. The recent revisions to the code now mean the requirement for mandatory site waste management plans has been dropped, as these are now a general requirement. Lifetime Homes measures are now a requirement for level 6 of the code, although there is an exemption for steeply sloping sites.

Social housing providers must already build homes to level 3 to receive government grants and all new homes have to be assessed against the code. Some local authorities, including in London, require social housing to be built to code level 4.

There is a question mark over the future of the code, the current administration says it wants to reduce the regulatory burden and has indicated the code could be merged into the Building Regulations.

All buildings need to be assessed for energy efficiency before being sold or rented.

The energy performance of the building fabric is assessed and the building is then given an energy rating on an A to G scale with A being the best.

Buildings over 1,000m2 that are occupied by public bodies and those where large numbers of the public visit, such as universities, need to display a certificate showing how much energy is actually being used. This is called a Display Energy Certificate and the rating is based on the size of energy bills.

There are also compulsory, five-yearly energy efficiency checks for the air conditioning systems installed in a building.


This Miller Homes development in Basingstoke includes homes with Code for Sustainable Homes ratings ranging from 1 to 6. The government’s recent change to the definition of zero carbon means building homes to level 6 now won’t become part of building regulations

Part G of the Building Regulations

This covers sanitation, hot water safety and water efficiency and took effect in April 2010. There is a limit of 125 litres of water per person per day, which is the minimum provision in the Code for Sustainable Homes.

Part G also defines where non-drinkable water can be used in homes and sets outs rules on water storage. This is intended to make installing rainwater and greywater systems easier.

Thermostatic valves and mixer taps are now required for baths to mitigate the risk of children being scalded by hot water.

CRC energy efficiency scheme

The CRC took effect in April 2010 and affects medium-sized organisations such as developers, central and local government, healthcare trusts and supermarkets.

These organisations must record their emissions and buy carbon credits to cover these emissions each April. Each October a carbon emissions league table is published. Originally the money used to buy the credits was going to be redistributed, with companies performing better than average receiving a cash credit. The scheme was changed in last October’s spending review so all organisations have to buy credits, regardless of their position in the league table.

The government will now also keep all the money raised from buying carbon credits without any recycling, effectively turning it into a carbon tax.

However, implementation has been delayed by a year - companies don’t have to buy credits until April 2012. The credits will be priced at £12/tonne and will add 8%-9% to energy bills.

Coming up

What’s changing this year?

At the end of 2010 the government announced its programme of change to regulations for 2011 with a view to implementing these in 2013. It is considering revising Part A (structure) and C (site preparation and resistance to contamination and moisture) in response to changes to structural Eurocodes and concerns about health risks from radon gas. It is also considering consulting on scrapping Part D (toxic substances) as this relates to a type of insulation no longer used in cavity walls.

Work will start on revisions to Part L and F and the government will look into rationalising Parts K (staircases and balconies), M (access to buildings) and N (glazing) due to conflict between these regulations and a “desire to reduce the regulatory burden.”

It also says it will look at how effective Part P (electrical safety) is, again with a view to cutting back on regulation, although a new regulation covering security is under consideration, and regulations that ensure disabled people have adequate toilet and changing provisions.

Part L

Work is just beginning on the 2013 revision to Part L. The overall target is another 25% cut in carbon emissions over 2010 Part L (44% over 2006) but this time round there is likely to be a move away from percentage improvements over previous versions of Part L to absolute figures. This will help bring Part L in line with the work the Zero Carbon Hub has done on defining zero carbon for housing. It has just defined and had accepted by the government the standards for carbon compliance (see below, the definition of zero carbon), which are expressed in kg/CO2/m2/year. These figures vary according to housing type. For example, the standard for low-rise apartments is 14 kg/CO2/m2/year, a figure that is equivalent to the percentage reduction in carbon emissions for 2013 Part L. This means carbon reductions are likely to vary according to housing type for the first time. As 2013 Part L is seen as a stepping stone to zero carbon in 2016 it could mean a less than 25% improvement over the current version of Part L for certain housing types.

On the non-domestic side, the revisions last year ushered in the aggregate approach, where standards vary according to building use. This was introduced to make the costs of improving different building types broadly similar. For example, it is more difficult to cut emissions from a supermarket than an office building so the standards for supermarkets were less onerous. This approach is likely to continue, with a refinement of the building types as the costs of improving a small high street retail unit are different from a department store. The timetable is tight: government wants a consultation on the changes out before the year end.


The German Passivhaus standard is becoming a popular route to creating low-carbon buildings. This office in north Wales was the first non-domestic building to become Passivhaus certified

Definition of zero carbon

The big news here is the government changed the definition of zero carbon for homes in the March Budget. Previously this included all the energy used by appliances in the home but now only includes the energy needed for space and water heating, fans and lighting. The idea is that this will reduce costs for housebuilders after 2016.

In practical terms this change makes very little difference to the work carried out to date on the definition by the Zero Carbon Hub. The definition is divided into a simple hierarchy, with a set amount of carbon emissions being mitigated by minimum standards for fabric energy performance.

The next step is “carbon compliance”, which is the minimum amount of carbon emissions that must be mitigated on site. This could include going over and above the minimum fabric efficiency standard and using onsite low and zero-carbon technologies.

The final step is so called “allowable solutions”, where the remaining energy comes from off-site sources. Under the new definition, fabric energy efficiency and carbon compliance will still apply, plus some energy from off-site sources will still be needed.

The fabric energy efficiency standard is set as a maximum figure of 46kWhr/m2/yr for semi-detached and detached properties and 39kWhr/m2/yr for all other homes. The carbon compliance levels include the minimum standards for energy efficiency plus additional mitigation of carbon emissions by going above these standards and employing low and zero-carbon technologies on site. The levels are 10kg CO2/m2/year for detached houses, 11kg CO2/m2/year for other houses and 14kg CO2/m2/year for low-rise apartments. The figure for high-rise apartments is yet to be defined.

The final job is defining allowable solutions. This is likely to include the export of heat to other developments and investments in low or zero-carbon community heat infrastructure. The Hub is now acting in an advisory role since the change of definition, the work is being carried out across government departments and the zero carbon task group. There is no timescale for defining allowable solutions, although the government is actively working on it.

Zero carbon for new non-domestic

A consultation on the last government’s ambition to make all buildings zero carbon by 2019 closed in February 2010. This proposed that regulated energy must be zero carbon and between 10% and 20% of energy for equipment is met from zero-carbon sources. The consultation also proposed the same hierarchy used for the definition of zero carbon for homes.

Because non-domestic buildings vary so much, there are different targets for different building types, 11 in total.

This was a proposal from the last government and to date there has been no official response to the consultation. As the definition of zero carbon from homes has been watered down it is likely zero carbon standards for non-domestic will do the same. If these proposals are implemented it will be done using Part L.

Energy performance of building

This is the Europe-wide instrument that gave us energy and display performance certificates (DEC). It is being revised to extend its scope and clarify and simplify existing provisions.

Proposals include extending the scope of DECs so they must be provided for all buildings over 250m2 occupied by a public authority or frequently visited by the public. The government recently announced in the Carbon Plan that it wants DECs extended to non-domestic private sector buildings by October 2012. The UK Green Building Council and the British Property Federation are calling for the Energy Bill, which is now going through parliament, to be amended to enable DECs to become compulsory but the business department is opposing it as an extra burden on industry.

A path to zero carbon?