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Technical
Part L changes and how they affect you
Changes to Buildings Regulations in England, due to take effect this month, include additional requirements when you install gas boilers and heating systems. Gas Safe Register’s Technical Team set out the main updates.
Building Regulations Approved Document L has been updated. The previous version of the document was split into four parts: • L1A – Conservation of fuel and power in new dwellings • L1B – Conservation of fuel and power in existing dwellings • L2A – Conservation of fuel and power in new buildings other than dwellings • L2B – Conservation of fuel and power in existing buildings other than dwellings.
The updated document now consists of only two parts: • Conservation of fuel and power,
Volume 1: Dwellings • Conservation of fuel and power,
Volume 2: Buildings other than dwellings.
Why does this matter to me?
With the environmental impact of burning fossil fuels driving many changes in the industry, these documents give guidance
on how to comply with Part L of Schedule 1 to the Building Regulations 2010.
While most of the information contained in these documents does not affect gas engineers, there are some parts in both new documents that will affect the work you do when you’re installing a gas appliance, most notably central heating boilers, and the wet central heating systems that they serve.
What’s new in Volume 1?
The changes mainly cover limiting heat losses through building services. The easiest way to do this is by insulating the hot water and heating pipework. As before, the guidance is that in a new system, heating pipework must be lagged when it passes outside the heated living space, including where it passes into a void. There is now an additional requirement that when a boiler or hot water storage vessel is replaced, any accessible pipes in the dwelling should be insulated.
All new hot water pipework
must be insulated – on both primary and secondary circulation – along with all pipework connected to a hot water storage vessel, for at least 1 metre from the point at which they connect to the vessel. The level of insulation required is given in Table 4.4 of the document:
for example, pipework between 11mm and 25mm would require 10mm lagging.
There is also guidance on
sizing heating and hot water
systems: systems should be designed following sizing methodology so as not be significantly oversized. An example of this can be found in the Chartered Institute of Plumbing and Heating Engineering’s Plumbing Engineering Services Design Guide.
When the central heating system is newly installed or fully replaced in an existing building, it should be designed to operate effectively at a maximum flow temperature of 55°C or lower. It is now a requirement to fit
thermostatic radiator valves
(TRVs) on all radiators except those fitted in the same space as the room thermostat. This also applies when replacing the boiler on an existing system. Previously this was good practice but not a requirement.
What’s new in Volume 2?
Volume 2 contains clear guidance for buildings other than dwellings. Again, most of the changes involve minimising heat loss. For instance, hot water pipework should be insulated in all areas inside and outside the building, unless it can be demonstrated that the heat is ‘always useful’. The insulation thickness requirements are different from those in Volume 1 and also differ for heating and hot water. The requirements can be found in Tables 4.4 and 4.5.
As in Volume 1, any new or fully replaced wet heating system should be designed to work effectively with a heating flow temperature of 55°C or lower. However, to maximise the efficiency of these systems, it would be preferable to design systems to work at a lower flow temperature than this.
Where pipework is run in a communal area of a building other than a dwelling but that contains a dwelling – such as in a block of flats – then Volume 2 is the Approved Document to follow for the communal area, and Volume 1 for the dwelling.
When do the changes take effect?
Both Volume 1 and Volume 2 come into effect on 15 June 2022 for use in England.
Wales has recently concluded a consultation period for its own version of Part L, and Gas Safe Register will update you further once these have been published.
There have been no recent changes to Technical Handbooks in Scotland or Technical Booklets in Northern Ireland. ■
This article is an overview of some of the changes that will come into effect this month. You can read the full Building Regulations Approved Document L Volumes 1 and 2 at:
