Neil Sawers, Commercial Technical Manager at Grant UK, explains how changes to the Building Regulations may affect domestic heating installers.
Changes to Part L (Conservation of fuel and power), Part F (Ventilation) and Part O (Setting Standards for overheating in new residential buildings) of the Building Regulations are the biggest set of updates to Building Regulations to affect the heating sector in over a decade. It is important to note that these Regulations only affect new and existing buildings in England.
The Devolved Government of Scotland will introduce similar changes later this year on 1st December 2022. Wales announced its changes in late May 2022 which are coming into effect on 23rd November 2022.
The ambitious changes to Part L1, which came into force in June 2022, set out an interim target of a 30% reduction in CO2 emissions relative to the 2013 version of the document. From 15th June, the thermal performance of a new building will see improvements in external wall U-values (down to 0.18W/m2K) and the heating systems for such new builds will have to be designed with a maximum flow temperature of 55°C or lower, which favours low-temperature, low carbon systems.
Time delays have also been significantly reduced. The previous iterations of the Building Regulations assisted the developer by allowing them an indefinite period of time to complete the site provided they started developing the site within five years of permission being granted. However, the new Regulations include a transitional arrangement for individual buildings where plans submitted after June 2022 or where construction has not started before June 2023 must comply to these new Regulations.
Similar changes to Part L2 will see a 27% reduction in carbon emissions on properties such as shops and offices. Approved document O is new to this suite of regulations and is aimed at preventing domestic dwellings overheating as a result of solar gains in the summer and provide a means of removing this heat through the use of cross-ventilation – this will be introduced to include domestic dwellings, offices and schools. Approved Document F deals with ventilation and these changes will bring about changes to increase the standard of ventilation in new homes.
While historical versions of the Building Regulations only applied to new buildings, the 2022 version tackles some areas relating to existing properties, which is particularly important when renovating an existing dwelling. For example, when a wet heating system is newly installed or fully replaced in an existing building (including the heating appliance, emitters and associated pipework), it must be designed to allow the space heating system to meet the heating needs of the dwelling at a maximum flow temperature of 55°C or lower.
If this is not possible, the space heating system should be designed to the lowest design temperature possible that will still meet the heating needs of the dwelling. It is likely that this will have to be justified before electing to use a higher flow temperature.
While this will not be a requirement for a simple boiler replacement, it makes sense to start improving the system efficiency of the existing system by reducing the flow temperature that will still work with the existing heat emitters. However, to do this, the new Regulations now require a full room by room heat loss calculation to be carried out prior to the boiler replacement.
Calculations
This change will affect installers of all heating system types, both oil, gas and renewable. While a thorough room-by-room heat loss calculation is standard practice for all heat pump installations, it has not previously been required for oil boilers. However, since 15th June 2022, all oil heating installations now require a room-by-room heat loss calculation carried out as part of the initial site survey. It is also worthwhile calculating the output of the existing heat emitters to offer advice on energy saving measures that could be introduced while changing the boiler.
In Section 5.8 of the new Regulation, it states that, “The specification of space heating systems should be based on both of the following:
- An appropriate heat loss calculation for the dwelling.
- A sizing methodology that takes account of the properties of the dwelling, such as the Chartered Institute of Plumbing and Heating Engineering’s Plumbing Engineering Services Design Guide.”
This means that a whole house type calculation is no longer allowed, something that will have a huge impact on installers who are requested to replace a boiler in a distress situation.
The section then goes on to say that, “systems should not be significantly oversized” – and here there is some ambiguity. The Regulation’s purpose is clear, in that the selected boiler should match the calculated heat loss as closely as possible.
The queries arise when you look at combination boilers where the output has been historically sized for the domestic hot water performance and not space heating requirements. For example, a 36kW boiler may currently be satisfying a heat loss of 14kW – is this significantly oversized or acceptable? Should installers be discussing the ‘oversize’ element with their homeowners with the view of potentially installing a traditional boiler/cylinder system (instead of a combination boiler) allowing a smaller boiler to be installed?
While these changes to Building Regulations do raise some questions, there is no denying their overall aim which is to serve as a stepping stone towards the forthcoming Future Homes Standard.
Grant UK’s eLearning Academy features an updated training module on Part L of the Building Regulations as well as other training modules on renewable products, and heat loss calculations. Visit the Academy at www.grantuk.com/professional/training/academy
