Introduced in 2005 the new Building Regulations Part L has changed the scene as far as boilers are concerned. According to the new requirement, all boilers replaced or installed must be of high efficiency rating. This includes condensing and combination boilers which utilize a larger heat exchanger (or a secondary heat exchanger) to recoup some of the heat that would normally be released into the atmosphere with the exhaust gases. Since some of the energy can be reused, the boiler can generate the same amount of heat with less fuel.

The new high efficiency heating unit introduced a new level of professional requirements from the system designer and the operative installing it. Each part of the system (such as the boiler, the radiators, the hot water cylinder and the heating controls) is fully integrated with the other components, to maximize the system's efficiency and heating output. As such, the design has to account for each component's specific set up and consider their input and output demands.

Industry research calculated that since the introduction of part L of the building regulations, the savings of carbon emissions made by the UK domestic heating market have been substantial. Recently conducted research puts the amount of carbon emission reduction at around 2.4 million tonnes. The researchers further calculated that if the industry did not apply the new Part L requirements, and continued installing SEDBUK D rated boilers, the carbon emissions from domestic heating would have grown by over one million tonnes since 2005.

At current levels there is still large potential for reducing the carbon emissions generated by the domestic boilers in the UK. There are around four million old boilers which are significantly less efficient than modern SEDBUK A rated boilers. Replacing such old boilers with an A rated boiler can reduce carbon emissions by around 30%. Each home in the UK produces an average of 5 tonnes of CO2 per annum. Across the whole population, domestic heating accounts for around 16% of the UK's CO2 emissions.

The UK government is actively trying to encourage carbon reducing behaviour through legislation. The government introduced measures such as zero stamp duty on carbon neutral homes and instructed all home sellers to produce energy performance certificates as part of their home information pack. It is, nevertheless, important to put it in perspective, as there are very few carbon neutral homes in the country and the savings should be focused on the highly inefficient homes. There is additional criticism that home information packs only apply when homes are sold and make no carbon reduction related impact at other times.

Other levers that can be pulled to reduce carbon emissions from domestic heating in the UK are related to renewable and sustainable energy. The government plans to build around 3 million new homes between now and 2020. If just 10% of these new homes use solar thermal heating or heat pumps along with traditional (gas or oil) boilers, around 150,000 tonnes of carbon emissions would be saved annually.

There are several options for the government to reduce the carbon emissions from the UK housing stock and meet the challenging targets it set. It is important to note that any relevant plan would be met with a prepared and professional group of plumbing and heating companies that are investing in professional development and staff training for the new technologies.