U-values tell us how effective a material is as an insulator. The lower the U-value, the better the product is at keeping heat in the house.
U-values are measured in Watts per metre squared Kelvin, or W/m²K. Typically, a cavity wall will have a U-value of about 1.6 W/m²K, a solid brick wall will have a U-value of about 2.0 W/m²K, and a double-glazed window has a U-value of about 2.8 W/m²K. So, whilst cavity walls are good insulators, windows are some of the worst.
How can U-values be improved?
Fitting natural insulation is an effective and environmentally friendly way to decrease your overall U-values and increase the warmth of your home whilst lowering your energy bills – perfect! Thermafleece insulation comes in varieties of British wool, hemp, and recycled materials so whichever you choose your conscience is clear (if a little green-tinted).