June marks the end of the grace period for the Building Regulations changes that came into force a year earlier, meaning that the rules apply to any projects that haven’t yet started and to all new work moving forward. 

There are some specific changes in relation to heating that must now be followed to make newbuild properties and renovations on existing properties compliant. But in recent conversations with our customers, we know many of you are unclear on what this means and are concerned about the cost implications for your own customers. In this article, we explain the key details for the Part L changes and how to navigate the new rules in your role as a plumbing or heating engineer.

The big picture

The changes to Building Regulations are largely positive and will help to improve the UK’s housing stock, which ultimately benefits homeowners. Sustainability is at the heart of the matter; the changes will lead to higher standards and help to make more energy efficient homes. The new regulations are also a stepping stone to bigger changes coming in 2025, when the Future Homes Standard will be introduced.

However, there has been a lack of communication about how tradespeople in different fields now need to change their usual ways of working, and the products they’d normally install, to be compliant. 

Changes to Part L concentrate on energy efficiency. All new homes, extensions, or refurbishments that are referred to Building Control will now be assessed under a new Standard Assessment Procedure (SAP) calculation, known as SAP10. The SAP calculation muse be performed at the design stage and again upon completion, measuring the Dwelling Emission Rate (DER) and the Target Emission Rate (TER). 

This becomes particularly important when considering the heating source of a property. As a plumbing engineer or heating installer, it’s vital that you know how to meet the new standards. 

How the changes impact your job

The government has set a target of reducing the carbon emissions produced by dwellings by 31%, and Part L – and heating systems in particular – will play a role in this. However, there are different requirements when it comes to new build properties and changes to existing homes. 

Newbuild homes

Gas boilers in newbuilds must now have a minimum efficiency score of 92%, while oil boilers must meet 91% – or 86% if it’s a combi boiler.

New wet central heating systems must be sized to operate at a maximum flow temperature of 55°C.

Once installed, a heat loss calculation must be carried out to ensure the new boiler meets this standard and isn’t oversized.

Any exposed pipework must be insulated, and thermostatic radiator valves must be in place on radiators in all rooms other than where the thermostat is installed.

The system must be balanced, as well as flushed, cleaned, and inhibitor added in accordance with BS 7593. 

As well as a mandatory airtightness test, property developers will also need to provide the owners of the new home with detailed information on their heating controls. These need to include where they are, what they do, and how to maintain comfort and minimise energy use. Plumbing and heating engineers should work closely with the developer to share this information so it can be collated and presented in a clear way for the future residents. 

Existing properties

Properties undergoing extensions or renovations that require input from building control will also need to adhere to the new standards. However, there is less to consider than if you’re working on a newbuild. 

Primarily, the main change relates to new or full replacement wet central heating systems – including all radiators and pipework. Like newbuild properties, these should be sized for a maximum flow temperature of 55°C. If the property doesn’t allow for the system to be sized in this way, the system should be designed for the lowest achievable flow temperature possible. This decision has been made to make it easier to retrofit heat pumps in the future. 

Products needed to meet the new Part L

Solar panels and heat pumps should be considered for any new homes and extensions, as they can help you to pass SAP10 measures. Part L favours renewable and low carbon energy sources over traditional alternatives, and the regulations state that any newbuild properties with gas central heating or an electric boiler must have solar PV by law. If not, you must install a ground or air source heating system to meet the SAP10 requirements. 

Wastewater heat recovery systems are also included in the range, as Part L recommends that they are used in any newbuild projects. The systems can convert heat that is lost down the drain into heat for new water and can be retrofitted into existing bathrooms or installed into new ones. 

Using these products may mean that costs of your projects rise, and therefore need to be passed onto homeowners. It may be particularly useful to explain the wider context of the changes in these instances, informing them that the steps you’re taking are to not only futureproof their home but to comply with the new regulations. 

Planning is key 

Now the grace period is over, make sure you always allow plenty of time to plan and purchase compliant products. Those that meet the new regulations will be in high demand, so purchase from a merchant, like Jewson, that has the necessary stock levels to help you complete your project on time and within budget. You could also consider using the Build Aviator estimating tool which guides you through the products and expertise required to remain compliant, and then collaborates with Jewson to ensure you’re receiving products at the right time for each stage of your project. 

This is a period of change that will inflict challenges on the industry, but if we unite to navigate and fully understand the new landscape, there are opportunities and rewards for all involved. Jewson’s downloadable guide contains further details about the changes and how they might affect you.