There are some calculators for various construction methods but they tend to make blanket assumptions.
In particular I assume I have a solid concrete floor without insulation.
Can anyone point me to U-values for walls, floors for various existing constructions?
My intention is to make my own calculations for what could be described a 'composite' property!
Further to above. Take the reciprocal of the "U" value (="R" value.) for the various components of your structure. Add together. Take reciprocal of total to get back to"U" value.
Many thanks.
The table references:
which is a US site. The numbers seem too small. For instance a "double pane" window is claimed to have a "U" Factor of 0.7, whereas I would expect it to be double that. In short I think the values here are using Fahrenheit temperature scale.
Yes - works rather like electrical resistance (which is should as it's a symmetric problem with a linear relationship:
delta-T ~ Voltage Power (W) ~ Amps Thermal Resistance ~ Ohms
The analogy regarding resistance is good, except you would add resistor values when in series.
I also find it hard to come to terms with thermal power and amps, as electrical power tends to follow a square law of voltage (and ampage).
That's brill, many thanks.
The only missing info is the different types of cavities and the effect of an air gap.
There are only two numbers for cavities which seem a bit low for my cavity with brick inner and outer skins. Somewhere else I came up with a figure of 1.5W/m2/K
If you find more reliable looking references, feel free to update the wiki with extra values or qualify some of them with ranges of typical values.
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