Decarbonisation: what are the options for specifiers?

The grace Part L of the Building Regulations ended in June 2023 and below we discuss solutions that specifiers could consider to help decarbonise the UK’s housing stock.

The revisions to Part L were introduced alongside changes to Part F and the introduction of Part O (ventilation) by The Department for Levelling Up, Housing and Communities (DLUHC).

The legislation came in as a response to the public consultation on the Future Buildings Standard in June 2021 and includes a number of interim uplifts, which are seen as a stepping stone to ensuring that all new homes built from 2025 are net zero ready and will produce 75% fewer carbon emissions than those built under the 2013 regulations.

Knowing the facts

The regulations came into effect on 15^th June 2022 with a grace period until 15th June 2023 to allow projects that were already in the planning process to continue.

This meant that any projects with planning permission under the old regulations needed to start work by 15^th June 2023, otherwise the new regulations would have applied, regardless of permission being granted before this date.

Key updates to Part L include:

• All new homes must produce 31% less co² emissions compared to the 2013 standards
• New heating systems must be designed with a maximum flow temperature of 55°C
• Heating zones within a home will need to have system control devices designed into them
• An onsite audit will be required on new builds to confirm that they have been constructed in line with the (Building Regulations England Part L) BREL report

In addition, by introducing the requirement for on-site audits and evidential photographs, there is now a greater focus on quality assurance, transparency and accountability. So, specifiers and designers will need to ensure that any work carried out is compliant with the requirements of Part L.

So, what are the options?

These changes, in conjunction with the decarbonisation of the energy grid, are intended to help the UK to move away from our reliance on gas. This is all part of the push to encourage designers, housebuilders, developers and homeowners to consider – and implement – alternative technologies that are able to provide low temperature heating.

Of course, changing heat distribution systems across the UK will be no small feat. In fact, research published by the BEIS in March 2021¹ found that up to 90% of all heating systems may need to be upgraded in order to provide adequate thermal output at a lower temperature on a cold winter’s day.

This will mean a complete rethink when it comes to the heat emitters that we currently design and install in homes across the UK. This is because in order to run efficiently at a lower temperature, the sizes of traditional radiators would need to increase significantly, which is something many homeowners would not want, particularly when there are space limitations or where aesthetics are a concern.

While there are already numerous renewable energy sources available, such as wastewater heat recovery (WWHR) units and solar PV panels, it is anticipated that heat pumps will become the primary heating technology for new homes. In fact, the Government has already set a target to install 600,000 heat pumps per year by 2028.

But which heating systems will work at lower temperatures?

Traditional convectional radiators usually have only one or two square metres of heat emitting surfaces and distribute heat upwards towards a ceiling, which – as many of us will have experienced – can lead to temperature differentiation (hot and cold spots) within a room. However, as radiant heating systems, such as UFH, have a very large heat emitting surface they can provide an even spread of radiant heat across the entire space.

Due to this larger surface area, underfloor heating systems are naturally designed to run at a lower temperature which means that they are ideally suited to work effectively alongside both air source heat pumps (ASHP) and ground source heat pumps (GSHP). The overall efficiency of a heat pump is determined by the temperature output from the heat source – the lower the supply temperature, the higher the pump’s performance factor. So, with underfloor heating systems running at between 35°C-55°C, as opposed to a traditional heating system running at around 70°C, UFH enables heat pumps to work at their most efficient capacity.

In fact, both Part L and the Future Homes Standard feature UFH as a recommendation for low temperature heat emitters in dwellings and other buildings. This recommendation is further backed by the UK Energy-related Products Policy (ErP) Study³ which indicated that there could be considerable savings from moving to low temperature emitters. Not just when it comes to carbon emissions, but when it comes to energy bills, too.

And what about zoning a home?

When it comes to radiators, thermostatic radiator valves (TRVs) could be an option for controlling individual rooms. However, a further benefit of underfloor heating is that it is already designed for zonal control meaning that each area can be controlled individually from a central thermostat, smartphone or even voice control systems such as Alexa.

Being able to control individual zones or rooms provides an enhanced thermal environment as people tend to prefer a different temperature at varying times in a bedroom to a living room or bathroom. But, on top of this, it also allows residents to turn off the heat in some rooms and not others, which means that only the rooms in use can be heated instead of the entire home. This minimises the amount of waste heat produced and further reduces a home’s carbon emissions.

Meeting the demands of tomorrow

While the standards and legislation place a big focus on new builds, it’s important to remember that these properties will not always be ‘new builds,’ they will become the homes of future generations and therefore need to be able to meet the demands of tomorrow.

It’s not that the innovation isn’t already here. In fact, numerous solutions for low temperature heating are already available. The main thing to do now, is implement them.

But it isn’t just about compliance to legislation. Energy efficiency is becoming an increasingly important factor for people when buying a home and it has now become a significant element of their purchasing lists. So, designing energy efficient, low temperature heating and cooling into our buildings is vital if we truly want to lower carbon emissions and provide homes that will be fit to meet the needs of the planet – and the people – of the future.