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  • Writer's pictureCliff L'Aimable _Chartered Surveyor & Building Engineer

40% total energy is used to power and heat your homes

Updated: Jan 15, 2023

Currently, heating and powering buildings in the UK accounts for a staggering 40% of our total energy usage. Making buildings more energy efficient, increasing your insulation, as well as eliminating un-wanted cold air draughts, will reduce demand for expensive energy, as well as saving you as homeowners lots on your energy bills.

Building Control Surveyors_Approvals
Building Control Surveyors_Approvals

The roof is one of the primary places in your house where precious heat is lost, so it must be adequately insulated to save energy (and money), and ensure that your loft conversions for instance or other extensions, can be comfortably used all year long.

Properly designed insulation can keep you cosy in the winter, and can help reduce excessive solar gains during the summer.

Additionally, it needs to fulfil the energy efficiency goals outlined in Part L of the building regulations – Hmmmm … starting to sound a bit techy already.

BCS Approved Inspectors_ Part L
BCS Approved Inspectors_ Part L

Ok well, “Part L” of the building regulations outlines the required level of insulation, basically expressed in “U-values”. Part L is the guidance published by the government which should be referenced when you carrying out certain building work in your homes or even places of work.

So what is all this talk about “U values” – well a U value merely defines the rate of heat transfer through a structure, which can consist of a single material, or a composite of various materials forming a sandwich, divided by the difference in temperature across that structure.

Basically put the slower the heat transfer, the better the insulation, the lower the U-value.

A building control surveyor (like me !!), will use the calculation to help determine compliance with building regulations, after your architect or designer calculates the thermal heat loss on your behalf.

In England right now, the U-value must be 0.15W/m2K for loft conversions, but this can change as the government is on a mission to introduce more and more stricter measures to lower the nations energy heat losses over the years ahead - especially during our energy crisis periods which appears to be with us for the foreseeable future.

BCS Approved Inspectors_ Part L
BCS Approved Inspectors_ Part L

There are numerous insulant materials to choose from, and each will require a different thickness to meet the minimum U-value requirements.

If you actually read the building regulations (the law) and the approved documents (e.g. Part L) that go with them, you would discover that they do not actually specify what materials you should use, let alone how different components of construction, like plasterboards, vapour membranes, insulants, timber rafters, battens, and breather membranes, should be combined.

Therefore, in the real world, one should aim, with professional advice, to achieve the best reduction in heat loss in a sandwich of construction made entirely of locally sourced, inexpensively produced, environmentally friendly materials, that are all as thin as possible.

This is especially important if you are forming, let's say, a loft conversion where final as-built headroom is already perhaps at a premium.

Your designer ought to be able to quickly think of different thermal options and combinations that are appropriate for your project.

This has been made even simpler by the fact that many insulation manufacturers have made their "U" Value calculators freely available online. This makes choosing materials simpler even for a computer novice to "have-a-go."

But there are a few things I want you to be aware of:

• Windows are the second-highest surface area of heat loss from your homes – design smaller windows which balance out with your needs for adequate light levels (which avoids you having to switch lights on during the day)

• Purchase efficient quality windows that keep your valuable room's heat in for longer periods, at the most cost-effective price—more "bang for the buck!"

• Insulate your floors, any roof eave voids (which may be used for storage), and any separating construction adjacent or below your new rooms to help soundproof your new rooms.

• To achieve the benefits of both sound and thermal insulation, remember to install insulated wall panelling between newly formed habitable loft rooms , that you share with your neighbour.

Insulating the rooms in your loft

Insulation is frequently added between or underneath the timber rafters of the roof, preferably both, to eliminate thermal bridging and the dreaded pattern staining effect simultaneously.

So what is patterning staining – well it describes the discoloration of plastered ceilings brought on by the different thermal conductivities of the underlying joists, steel beams, or other building materials, placed behind the plastered ceiling or even wall surfaces.

Building Control Surveyor
Building Control Surveyor

The air circulates more freely over the warmer parts, causing more dust to accumulate on them thus staining the surfaces.

And secondly, just to be clear, a thermal bridge is a location where thermal insulation coverage is not continuous, elevating the likelihood of increased heat loss and possibly condensation (or even mould) forming in various areas of your building that are connected to the outside air, where thermal bridges occur.

On window ledges and cills, thermal bridges can produce cooler regions that can draw moisture from the warmer air around them. This can cause the growth of mould, particularly in spaces that are just not regularly ventilated. These might even spread into the adjoining walls, posing a serious health risk to anyone living in the building.

Mold removal is furthermore a very expensive and time-consuming process. Such a situation can be avoided altogether with proper window thermal insulation and routine airing out of risky areas. This also holds true for door frames, leafs, and reveals because of how similarly effective their insulating characteristics are.

A vapour control layer, insulation, and perhaps plasterboarding is typically configured to lessen the likelihood of condensation and the risk of mould growth.

A wall separating a bedroom from an adjacent bathroom, for example, requires soundproofing on the inside and thermal insulation where the walls also connect or abut the outside air.

Blog written by Chartered Surveyor / Building Engineer Cliff L'Aimable :

As always if you are considering building something new, extending or improving your homes or places of work then give us a call – we offer very competitive quotes for the provision of private sector building regulation approvals. Tel 01992 710 763 or email: get a fee quote from

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