How do we quantify the effectiveness of external insulation?
Heat will always flow from a warm area to a cold one. In winter, the colder it is outside, the faster heat from your home will escape into the surrounding air. External wall insulation slows down the rate at which heat escapes, keeping as much of it as possible inside your home for as long as possible.
In the summer the enters into your home from the surrounding air. During summer the role of external insulation is to moderate internal temperate.
But how do we quantify this?
Thermal Transmittance (U-value)
The ease with which heat can flow through your walls is called the U value. The lower the U value, the more slowly heat is lost – and the more money you will save on your fuel bill to keep your home warm. It is measured in units of W/m2K. Click here for examples of recommended U-Values from current UK and Irish building regulations
Thermal Resistance (R value)
If we look at the U value upside down we get the R value which another term that is commonly used. It expresses the resistance of your walls to heat flow the so called Thermal Resistance. It is measured in units of m2K/W.
Since U and R values and R
values are the reciprocal of one another once you know one you can figure out the other. They both give an overall figure which tells you how good your walls are at keep you warm.
U is the reciprocal of R-value; U=1/R
Thermal conductivity (λ value)
The only other figure to concern yourself with is “Lamba”, this is a measure of the effectiveness of an insulation. The reason a good wool jumper will keep you warmer than a nylon jumper of the same thickness, is because the wool jumper has a lower Lamba. So for your external insulation, you want insulation with as low Lamba as possible for your euro. Lambda is measured in Units of W/mK. See here for some common lambda values
Contact us now to learn how your home can benefit from External Wall Insulation.