How to calculate how much energy your windows will save from its U-value

Old cottage made airtight and insulated with woodfibre insulation

The number assigned to a building fabric element (eg, a window) that represents its thermal resistance is called its U-value. A U-value tells us how quickly or slowly it takes for heat to pass through it. Fabrics with lower U-values are better insulators than those with higher U-values. Part L of the UK Building Regulations … Read more