Thermal imaging surveys – a good idea?

Thermal imaging surveys – a good idea?

10:39 AM, 4th April 2023, About A year ago 7

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Hello, Thermal imaging surveys – are these a good idea? I am considering one for my own home to determine where there might be some obvious heat leak areas. Ideally each room scanned, as well as the building as a whole.

Anyone had any experience of them – do they really ‘see’ and are able to identify cold bridging areas to the degree they can also give recommendations as to how to address cold spots? Do they produce evidential reports?

From what I can see they charge from around £450 or so, but you can buy a camera/hand held one for not much more and then have the option of checking your own rentals.

Thank you,

Reluctant Landlord


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G Master

10:58 AM, 4th April 2023, About A year ago

I vouch for that. I nearly bought one for my own home but they are over £330 and I might use it once only.
But it is ideal to see where the heat loss is occurring.

Reluctant Landlord

11:18 AM, 4th April 2023, About A year ago

Reply to the comment left by G Master at 04/04/2023 - 10:58
Did you get someone in? I've been thinking about this too but wondering who to use.

G Master

11:57 AM, 4th April 2023, About A year ago

I have not made up my mind yet. It needs to be done but I am looking for a cheaper alternative. Another source of this is the people who come to install cavity wall insulation. They would show the heat loss free to you.
If I decide to do something then I will let you know for sure.

Robert Locke

12:00 PM, 4th April 2023, About A year ago


I'm both a Landlord and a Certified Passive House Consultant focusing on retrofits.

Thermal imaging can be useful, if the results are correctly interpreted. A lot of the images you see on news websites fail to show the scale in the image, making the image more-or-less useless as the colour gradients vary between the warmest and coolest part of the image - that variation could be 10, 1, or even 100°C. You'd be admonished by a teacher for handing in a graph without scales, yet publishing these images in the national press without scales is perfectly acceptable!

It's best to start on a macro-scale. Try using the IR camera externally first thing in the morning, with the heating on. This way the sun hasn't had a chance to warm the external surfaces, and you'll be able to clearly see where the greatest heat-loss is.

Next, work internally. missing insulation is usually pretty obvious, but check around light fittings and sockets in particular. These can be a source of air leakage - you can lose up to 80% of the effectiveness of insulation through convection, as well as risk damage from moisture in the air reaching cost, inaccessible surfaces.

Improperly detailed junctions between ceilings and wall, walls and floors, walls and windows can be huge sources of thermal bridges', where the depth of insulation decreases due to structural components. The losses through thermal bridges can add up to a significant chunk of the heat losses in a home. Humidity is drawn to these cold spots, increasing the risk of mould growth. This is particularly true when insulation is increased elsewhere as the square-meterage of cold surfaces decreases, leading to a greater amount of condensation on the remaining cold spots. Designing out these thermal bridges is my bread-and-butter. Ventilation is key, of course, but when thermal modelling, the aim is to keep any internal surfaces about 17°C to remove the risk of condensation, no matter the relative humidity.

Whatever you choose to do to improve EPC performance, make sure you're designing out thermal bridging as up-front cost savings could well lead to greater costs down the line for mould mitigation or getting into inaccessible spots that could have been properly dealt with earlier.

Reluctant Landlord

12:21 PM, 4th April 2023, About A year ago

Reply to the comment left by Robert Locke at 04/04/2023 - 12:00
thank for the detailed info - gave me more insight. My own house was a new build 20 years ago but I suspect that the cavity wall insulation is a bit hit and miss as some rooms colder than others. Too late to go back to the builder now. Was thinking of having the old stuff sucked out and replaced with new thinking this might help.

If biggest heat loss from bridging areas/junctions, what can be done in your opinion? I don't particularly want to start hacking into plaster at room corners... how would you insulate these areas anyway?

You got me thinking now!

Robert Locke

12:55 PM, 4th April 2023, About A year ago

Reply to the comment left by DSR at 04/04/2023 - 12:21
Most cavity wall insulation in new-build properties is in slab form, inserted between the cavity wall ties as the wall is constructed. Injected/blown cavity wall insulation is used in older properties with an empty cavity void from when the installation wasn't mandatory. As such, 'sucking out' and starting again with the cavity insulation is unlikely to be an option. If you can precisely locate the cold spot, it should be possible to have an installer inject cavity insulation into that zone only. If the cold spot looks quite small on an IR image, it may be due to something physically bridging the cavity such as a glob of mortar, which will need some bricks removing externally to be accessed.

Wall-to-wall junctions tend not to be massive thermal bridges, unless the property has solid (i.e. not cavity) walls. I've got multiple ways of tackling this on a case-by-case basis. If the surface temperature and u-value of a cavity wall is still lower than required, it may be possible to increase the amount of cavity wall insulation (assuming a partial cavity fill exists), or start looking at internal or external wall insulation, timed to coincide with the redecoration of the property. Any insulation used will have to be suitable for the materials the property is already made of to avoid risks due to interstitial condensation (e.g. no foil-faced of petroleum based insulation in pre-war properties).

Most of the time, the eaves junction (ceiling to wall) is a big culprit for thermal bridging. Once any air leaks from the habitable rooms to the roof have been sealed, it's usually a case of adding an appropriate rigid insulated baffle to the eaves to allow necessary airflow to the loft, appropriate insulation over the wall plates to reduce thermal riding and then adding insulation to a depth of at least 270mm (preferably 500mm). The type, size and location of said insulation vary on a case-by-case basis, but takes into account the existing materials, roof pitch and overall roof geometry.

I'm, not allowed to advertise here, but Google is your friend...

Wyn Burgess

14:13 PM, 8th April 2023, About A year ago

Reply to the comment left by Robert Locke at 04/04/2023 - 12:55
I'd love a IR camera but it would get enough use to justify purchase. I use an IR thermometer,
really useful for identifying cold spots in a room (by plotting the readings at intervals on a wall or ceiling) to prove condensation is the cause rather than a defect with the structure.

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