In 2005 the Building Regulations introduced the new Part L demanding all new boilers installed to be categorized as high efficiency systems. This includes condensing boilers and combination (also known as combi) boilers which use a secondary heat exchanger (or an extra large single heat exchanger) to recoup the heat that would otherwise be expelled into the atmosphere via the boiler flue. The new Building Regulations Part L also called for heating controls, system insulation and hot water cylinders among other components to improve their respective energy efficiency levels.

The new requirements are much more demanding than previously in terms of the professional level of the system designer, the installer and the service engineer. The new systems are more integrated than old systems as all components are specifically designed to provide the right output (in terms of power) or demand the right input (such as in the case of heating controls). The engineer has to have good understanding in order to maximize the efficiency of the system.

Research shows that since the introduction of the new Part L, the domestic heating industry has made a major reduction in the amount of carbon emissions generated every year. Recent analysis conducted in the industry indicates that savings of around 2.4 million tonnes of carbon have been made since the new Building Regulations have been introduced. Furthermore, the analysis shows that had Part L not been introduced and with the industry relying on SEDBUK D rated systems, the amount of carbon emissions would have increased by over one million tonnes since 2005.

At present there is still plenty of room for improvement in terms of the amount of carbon generated and emitted by domestic heating in the UK. There are around four million old boilers still installed around the country which have significantly lower efficiency compared to modern A rated boilers. Installing a modern A rated boiler as a replacement, would reduce their respective carbon emissions by around 30%. A typical home in the UK generates around 5 tonnes of carbon dioxide emissions every year. Overall carbon emitted from domestic heating sources is responsible for around 16% of the total UK national CO2 emissions.

The government is trying to encourage carbon reducing behaviour within the home heating sector. It has scrapped stamp duty for carbon neutral homes and has introduced the home information packs which have an energy performance certificate as part of the pack. However, the stamp duty benefit does not apply to the vast majority of inefficient homes around the country making it less effective. The home information packs (with their energy performance certificate component) also have drawbacks in that they are only produced when the house is sold, and thus not having enough of an impact at other times to encourage reduction in carbon emissions.

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.

The government applied a combination of carrots and sticks to force the domestic heating market to reduce its carbon emissions. The plumbing and heating industry is largely keeping up with the trend with many companies investing in training and professional development on renewable energy technologies to address any market need in those areas.