The thermal transmittance of a building element (like a wall, roof, window, or floor) is a measure of how well it conducts heat, and is expressed as a U-value. The lower the U-value, the better the material is at insulating against heat loss in winter, or heat gain in summer. The overall U-value of a building element depends on the layers of materials, their thickness, and how they are assembled. The thermal resistance, or R-value, is the inverse of the U-value, where a higher R-value signifies better heat retention.
The Scottish Building Regulations require new buildings to meet stringent maximum U-values for different elements of the insulation envelope. When undertaking work on an existing building, the regulations require the insulation envelope to be improved as much as is practicable. The aim is to meet the recommended U-values for a new build, or at least to significantly improve upon the existing levels of insulation.
Read more about how Sparran can help determine appropriate U-values for your project here.