Knowing the Facts - The New Part L Regulations

With new changes to Part L Building Regulations having come into place in June, it is important for installers to be aware of all the new legal requirements that will apply to their work in both new and existing heating systems, when the heat source is replaced.

These new regulations are a lot to digest, so here’s a simple breakdown of the key points!

 

Fabric First Approach

A ‘fabric first approach’ means that methods are put in place to maximise the performance of the components that make up the building fabric within a dwelling, such as insulation and glazing. A target of 31% decrease in carbon emissions has been set as a result of this approach, as the Government hopes to meet the target of a 75-80% decrease by 2025 in the ‘Future Homes Standard’.

 

Heat Loss Calculations

A major difference between the old and new Building Regulations is that heat loss calculations will now be required for every room in a dwelling, rather than just for the dwelling itself, when installing a replacement boiler. This is to ensure the heat source is not oversized.

An installer will need to calculate heat loss for all heating system types, including oil, gas and renewable systems.

Examples of appropriate sizing methodology can be found in CIPHE’s Plumbing Engineering Services Design Guide.

 

Flow Temperatures

Continuing the push towards low carbon heating systems, the new requirements state that these systems must have a maximum flow temperature of 55 degrees, compared to the previous standard of 80 degrees.

If this is not possible for an existing installation, the new requirements state that the space heating system should be designed to allow the lowest possible flow temperature to be used, whilst still meeting the needs of the dwelling.

 

Gas Boilers

Minimum energy efficiency for heating systems has been set as part of the new requirements, with 92% ErP for gas boilers and a SCOP of 3.0 for heat pumps.

High efficiency condensing gas boilers will meet the minimum requirements for Part L, but only when combined with secondary energy efficiency levels such as:

• Solar PV panels
• Underfloor heating
• Wastewater heat recovery
• Flue gas heat recovery

 

Continuation of the Boiler Plus Scheme

The ‘Boiler Plus’ requirements were set out in 2018 and remain the same. These requirements state that a gas combination boiler (whether this being installed in a new or existing system) must include one of the following:

• Weather compensation
• Load compensation
• Flue gas heat recovery
• Smart control with automation and optimisation functions

More information on the Boiler Plus Scheme can be found at… https://www.beama.org.uk/resourceLibrary/resource---boiler-plus-changes--april-2018--docx.html

 

Heating Controls

With the new Part L requirements, when a replacement heat source is installed, every room will require thermostatic room controls. The thermostatic room controls can consist of thermostatic radiator valves (TRVs), thermostats, programmers, boiler interlocks, cylinder thermostats or independent HW time controls, and must be able to be used to separately adapt the heating output in each room service by the heating appliance.

With most heating systems having radiators already installed, adding a TRV onto these radiators in each room is the least obtrusive way to meet this requirement. By ensuring that each room is maintained at a comfortable temperature, they avoid any overheating in those rooms that will be a waste of energy. This will include reducing the heat output of a radiator when the outside temperature increases, at times when that room is getting a lot of sunshine, or when additional heat is generated by people or electrical appliances in the room. The boiler will sense when the TRVs are closing and either turn off or reduce the amount of heat it produces in response to this.

 

Water Treatment

Mandatory water treatment for every heating system, is now recognised by reference to BS 7593: 2019. This outlines the best practices for the preparation of the primary wet central heating systems. Each system should be designed to allow for efficient cleaning and flushing and addition of water treatment chemicals. Good practice during installation should limit the ingress of installation debris such as millscale, metal swarf, soldering flux, jointing compounds and grease.

By aligning with this British Standard, the new requirements for Part L ensure that potential problems are highlighted, and measures are put in place to maintain the efficiency and maximize the life of heating and cooling systems.

 

Balancing is Best

Whenever a heating system is designed, the intent is to deliver the proper rate of heat transfer precisely when and where it’s needed within a building. Without proper balancing and adjustment, that goal is almost never achieved. The most obvious consequence of an improperly balanced system is lack of comfort and wasted energy from room air temperatures that are too high, too low, or both.

To overcome this, and to ensure that a system remains compliant to the new Part L regulations, it should be best practice to balance a system. This can be done using balancing devices, with the designer of any system calculating the flow rate required to each terminal unit and selecting the type and size of the balancing valve to control the flow based on the type of pumping system utilised (constant speed or variable speed).

 

The Future of Building Regulations

Looking to the future, building regulations will see a complete overhaul in 2025 as the Future Homes Standard and Building Standards will be in place. These will be an additional steppingstone to meet the UK’s NetZero target in 2050.

It is important for all installers to consider both the new requirements, and best practice to ensure that these requirements are consistently met, and maximum efficiency is achieved.

 

If you need any further support with the new Part L regulations, please email technical@altecnic.co.uk.