Part L1A and L1B  Building Regulations Documents Covers

Last November delayed reforms to building regulations were introduced in the UK, providing guidance on Conservation of Fuel and Power in new domestic (L1A) and non-domestic (L2A) buildings. These come into effect from 6 April 2014.

But the government has been accused by MPs of frustrating attempts by sectors of the building industry to improve the energy efficiency of homes.

For domestic properties

The main improvement under the revised building regulations is that CO2 emissions from domestic properties are required to be 6% better than 2010 regs.

There will be a requirement to calculate the fabric efficiency of the dwelling, which must meet or exceed the target in the same manner as the dwelling carbon dioxide emission rate (DER) and TER (target carbon dioxide emission rate). Fabric energy efficiency is measured in kWh per square metre of floor area, and takes into account the space heating and cooling demand. The CO2 emissions, on the other hand, are measured in kg of CO2 per square metre of floor area and the calculation only takes cooling into account for dwellings that use mechanical cooling.

To achieve compliance, both the fabric energy efficiency and CO2 emissions must be below those of a notional dwelling. This notional dwelling has been redefined such that an emissions reduction of 6% is achieved, compared with dwellings that meet 2010 standards.

The Fabric Energy Efficiency Scheme (FEES) assesses the kwh/m2/pa required in the property using the U-values (these are the inverse of North American R-values), air tightness and thermal bridging specification; it ignores heating, heating fuel and renewables.

Backstop U-values have not changed but the values required will need to be far superior. A sample set of U-values (and other SAP inputs) have been published which will meet the requirements of part L1A.

Greater emphasis is placed on reducing the heat loss through party walls and the evidence required to demonstrate compliance with each of the stated U-values. Updated values for thermal junctions when default values not used are also given.

Nondomestic properties

The methods of compliance for new non-dwellings have not changed significantly, but the CO2 emissions reduction required is greater than for dwellings: 9%. This means more energy efficiency measures will need to be incorporated, and even though renewables are not a requirement, more designs may incorporate them as a means of achieving the CO2 target.

By building type, the required improvements are:

  • Distribution warehouse: 9%
  • Deep plan office with AC: 12%
  • Retail warehouse: 8%
  • Shallow plan office: 13%
  • Hotel: 12%
  • School: 9%
  • Small warehouse - 3%.

Limiting fabric parameters remain unchanged however these will need to be far superior for the actual building. Limiting U-values are now:

  • Roof: 0.25W/m2.K
  • Wall: 0.35W/m2.K
  • Floor: 0.25W/m2.K
  • Windows, roof lights: 2.20W/m2.K
  • Vehicle access doors: 1.50W/m2.K
  • High use entrance doors - 3.50W/m2.K
  • Rood ventilators: 3.50W/m2.K.

Air permeability remains unchanged at 10m3/(h.m2) however this will need to be far superior for the actual building.

For both domestic and nondomestic buildings architects must provide building control with design stage calculations before work is started on site. A document considering high efficiency alternative systems for the dwelling must be produced and made available to building control. It should consider the technical, environmental and economic feasibility of using high efficiency alternative systems:

  • decentralised energy supply systems based on energy from renewable sources;
  • cogeneration eg CHP;
  • district or block heating/cooling;
  • heat pumps.

Also 'as built' calculations must be provided to building control within five days of completion.

Some of the minimum plant efficiencies set out in the Non-domestic Building Services Compliance Guide have been upgraded. One example is the minimum efficacy of lighting in office, industrial and storage areas has been upgraded from 55 to 60 luminaire lumens per circuit-watt.

Changes to the Approved Documents for existing buildings – L1B and L2B – are minimal. But they do stipulate that changes should be made in accordance with Standard Assessment Procedure 2012, not 2009. 

The Code for Sustainable Homes

These improvements to Buildimng Regs come just after the UK Housing Secretary has reduced the need for developers to build homes from 2016 that are 'zero carbon', meaning that the UK is taking two steps forward and one step back in promoting energy efficiency in buildings.

Housing Secretary Eric Pickles said in October that he would remove a policy that has delivered sustainable homes and supported the low carbon construction sector for several years, because he thought it was providing a brake on the building of new homes which are desperately needed across the country.

But his decision was severely criticised by a committee of MPs, the cross-party Parliamentary Environmental Audit Committee, which said that his department, the Department for Communities and Local Government (DCLG), was wrong to axe the Code for Sustainable Homes (CSH).

Although it is optional, the Code has been used widely by local authorities and others to drive up sustainable house building and help drive down carbon emissions from Britain’s housing stock.

Pickles is instead proposing using building regulations or national standards as the driver for greener homes.

The Environmental Audit Committee said scrapping the Code would introduce a "lowest-common-denominator national standard" that would curtail local choice, drive up energy bills and damage the building industry and green exports.

"The Secretary of State should think again before demolishing the Code for Sustainable Homes," Environmental Audit Committee chair Joan Walley said. "The policy has been a big success in driving up home building standards, delivering local choice and supporting green exports. Building materials manufacturers in the UK told us that they use the Code as a green kitemark when they sell their products abroad.

"This decision bulldozes local choice in favour of a one-size-fits-all approach designed to benefit developers who want to build homes on the cheap," she added.

The Government introduced the CSH as a national standard in 2007. The Code measures sustainability against categories such as energy and CO2 emissions, water, materials, surface water run-off, waste, pollution, management, ecology, and health and well-being. Although not compulsory for every new home to be built to the Code, each home must contain a rating against the Code.

The construction industry is divided on the Code. The Home Builders Federation states that the Code is outdated and should be scrapped but the UK Green Building Council (UK-GBC) would like to see it retained in some form.

Jo Wheeler, senior policy advisor at UK-GBC, said: "The time was right for review and rationalisation, but any changes must support the delivery of high quality homes. With the demise of the Code and big omissions in the Housing Standards Review consultation around issues like materials, we risk losing a momentum that has transformed the way homes have been built over the last seven years."

"Hundreds of thousands of homes have to be built in the coming decades. Smart energy and water saving measures – which will ultimately save homeowners money on their bills – must become the norm if we want our homes to be fit for the future," said Walley.