15th May, 2023

Ask the experts: Dan Love discusses the impact of Part L


Ask the experts: Dan Love discusses the impact of Part L

With the grace period for compliance to Part L ending in June this year, if you haven’t already gained a good understanding of the new regulations, then now is the time to do your research.

Over the coming months we’ll be asking our team of experts about what the updated regulations mean for installers, specifiers, and merchants to help you gain a better understanding of the impact that the legislation will have on your role.

This month, we spoke to Dan Love, Head of Commercial at Polypipe Building Products, on how to accommodate the new flow temperature requirements in heating system designs and what the regulations mean for underfloor heating.

Why has Part L been updated?

Part L has been updated in an effort to significantly improve the energy efficiency of new and existing homes and buildings. Compliance with the regulations should result in a 31% decrease of carbon emissions produced by homes and a 27% decrease in other buildings. Meeting this goal will provide the industry with a step in the right direction when it comes to meeting the government target of net-zero carbon emissions by 2050.

The new regulations are also being implemented ahead of the Future Homes Standard, which is due to come into effect in 2025.The Future Homes Standard aims to ensure that homes are built with 75% less carbon than the previous regulations and will mean that all future homes are net-zero ready and will not need retrofitting at a later date. Of course, a 75% decrease would be a major jump from the previous Part L regulations. That’s why implementing the changes under the new Part L will provide a solid stepping stone for installers, developers, and homeowners before incremental changes need to be made in the second half of the decade.

What needs to be considered to meet the maximum flow temperature?

One of the major changes to the regulations is that all new and replacement wet space heating systems will now need to be designed for a maximum flow temperature of 55°C in order to keep the system efficient.

This means that those designingheating systems to meet the new requirements must consider updating heat emitters, such as radiators,which tend to run at higher temperatures.

The new regulations around maximum flow temperatures mean that traditional steel panel radiators would need to significantly increase in size to meet the new requirements, which is not always possible due to space constraints and aesthetics. For example, to provide 900 watts of heat output with a flow and return of 45°C/35°C, a double panel radiator would need to be 1800mm L x 600mm H compared to 1000mm L x 600mm H when using 75°C/65°C so nearly double the size.

This means that alternatives such as underfloor heating, which cover a greater surface area than radiators, should be a key consideration. These systems are designed to run at a lower temperature of between 35-55°Cfor maximum efficiency. This means that UFH can perfectly accommodate the optimal coefficient of performance (COP) for heat pumps, which is attained when they run at 35°C.

What if it’s difficult to size the system for 55°C in the case of a full system replacement?

If it’s not possible to achieve a flow temperature of 55°C – which may be the case in properties where there is insufficient space for larger radiators, or where the existing distribution system is provided with higher temperature heat from a low carbon district heat network–then you should design a system that achieves the lowest flow temperature possible, whilst still meeting the heating needs of the property.

How does Part L affect underfloor heating?

Whilst Part L does not specify requirements for underfloor heating outright, it does outline new requirements for the insulation of the flooring. These requirements demand that floors of new homes should have a U-value of less than 0.25w/m2k, along with a guidance note that if underfloor heating is installed the value should be no larger than 0.15w/m2K. It is also important to note that the regulations request that if underfloor heating is installed, insulation should be present beneath the system to limit downward heat loss.

However, as the main focus of Part L is on lower carbon emissions – and therefore an uplift in the usage of renewables such as heat pumps – UFH actually provides an ideal solution to ensure Part L compliance in most system designs. Not only is this because UFH systems are naturally designed to designed to operate at low flow temperatures (35-55C), but they are also already designed to be split into zones, which is another core requirement of Part L. Splitting the system into zones means you can control the levels of heat being emitted in certain areas, meaning that residents can heat only the parts of the property that are in use, and turn it off for any rooms in which heat is not required. Ultimately, this ensures that less energy is wasted as a result.

In fact, a UFH system will be between 15% and 40% cheaper to run compared to traditional radiators. This means that beyond compliance to the updated regulations, and thermal comfort, installers and developers can also promise homeowners that they will benefit from reduced running costs.

If there is anything you’d like to know more about or you want to ask us a specific question, why not contact our technical team and they will be happy to help.

Need some help?

Contact our technical team for advice today

Other helpful information you might like

Take a browse through our helpful content which will provide you with everything you need to know about how the regulations will affect you..


Heating Homes of the Future

The new regulations broken down and made simple



Find the answers to our most frequently asked questions

Get your free quote