Sustainable Building Glossary

Thermal comfort: Requirements for thermal comfort are stated in BS EN ISO 7730 from which the following figure has been taken:

Thermal mass: Thermal mass is calculated by multiplying the mass of a product by its specific heat capacity. The higher the figure the better a product protects from summer overheating and usually acoustic noise. Natural insulation products such as wood fibre boards perform extremely well compared to mineral/glass wool and other insulating materials because they have a significantly higher specific heat capacity and much greater mass.

Transmittance (U-value): The U-value of a physical body (e.g. wall) is the conductance plus the surface effects. It is related to one m² of the (building) component. The higher the value the lower its thermal resistance and therefore the more heat/energy passes through the element. Unit: W (m²K)^-1.