We would like to determine which elements of building are to be renewed or changed. Among other things, we want know which elements are subject to a specific heat transfer.

Does exist a measuring method to determine the real existing value of thermal transmittance (W/(m²·K)) or R-value ((m²·K)/W) of a bulding component (e.g. wall, roof, window glass, window frame, ...)? And what accuracy is there?

  • This could be identified with an energy audit. I have an FLIR camera that attaches to my phone it is great for finding areas of heat loss and even better for heat gain (loose or overloaded electrical wires). Even if we know your structure type and wall thickness we would need to know the type and amount of insulation to calculate it. Or just have an audit. IR cameras can also be rented and the FLIR one pro that I use has saved me many times it cost.
    – Ed Beal
    Jan 20 '20 at 15:05
  • I haven't read this, but this is a link to a paper describing a method to measure thermal resistance in a field setting. It's clearly not a simple undertaking. There are also methods and equipment for laboratory settings, but those require steady state conditions over extended time periods. web.ornl.gov/sci/buildings/conf-archive/1985%20B3%20papers/…
    – Mark
    Nov 17 '20 at 5:33

Window manufacturers will provide those values and they are used when designing the building envelope.

There are books and papers which have generic values for single, double and triple glazed windows, this is also available for all types of insulation used in the roof and walls..

Perhaps the easiest way to determine the worst performing parts of the building is to use a thermal imaging camera. Trying to remove, then test under laboratory conditions components would be challenging and difficult.

  • In the whole building are double pane windows installed. But there is condensation on some of the windows. Reasons can be the indoor climate but also the insulation effect. The valuation of window glass with the thermal imaging camera seems to be a special challenge (elements after the window, reflections). Data sheets and literature show that enormous differences are possible at window glass, 1... 2 m²·K/W. Therefore I would find it good to detect the heat transmission of installed elements in reality.
    – gotwo
    Jan 21 '20 at 13:07
  • As with any tool, knowledge, experience and understanding are key, but if you don't start you won't improve.
    – Solar Mike
    Jan 21 '20 at 13:19

If you know what makes up your wall (for example), you can find thermal conductivity (U-values) or insulating values (R-values) for most/all common building materials such as wood panels, drywall, insulating materials, etc. You can then just stack up the insulating (R-values) given the type and thickness of the material in your wall and come with a total R or U value.

For things like windows and doors, manufactures usually provide R or U value for their products.


For any changes concerning walls or roof there is a site providing an easy tool for calculating thermal losses, dew points and more. Each layer can be edited and switched on/off to instantly see any change if an insulation layer is added or removed. But it is mainly based on European materials and standards. It is free for private use. www.ubakus.de

Fastest way is to choose an adequate example (menu) and to edit the layers.

Disclaimer: I do not have any association with that web site, I do not benefit/profit in any way from my recommendation/mentioning of that site. It is just by far the most professional and sophisticated site to calculate and visualize the relevant insulation parameters that I have found up to now.

  • Please indicate your affiliation (or lack thereof) with the site you linked. Just to ensure there are no thoughts of spamming...
    – FreeMan
    Jun 18 '20 at 18:35

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