U/R Values overview U/R-values are used to describe the thermal performance of building elements including floors, walls, windows, doors and roofs. This data is then used to calculate the energy performance of the whole building which in turn can impact on the size and cost of the specified insulation, heating system and overall cost of the development. U/R-values are calculated using a range of computerised calculators and in some cases...

Airtight Membranes & SD values Often referred to as airtight membranes know but should be classified as - Vapour Checks Vapour Barriers Before we discuss the differences in 1 & 2 we need to discuss Vapour resistance, SD values and μ values. Vapour resistance The vapour resistance of a material is a measure of the material’s reluctance to let water vapour pass through. The μ (“mu-value”) of a material is...

Should new construction be windtight ? It sounds like an obvious answer but until now very few people even consider it. It is an important part of the construction fabric and although it may not cause the same heat loss or structural damage as ineffective airtightness its benefits should not be overlooked. This a change in thinking for many professionals who for years have been encouraged to have as much...

Passive Airtightness & MVHR V Building regulations We decided it would be interesting to see a cost comparison of a typical house designed to meet current building regulations and a house designed to achieve passive house levels of Airtightness including MVHR. The results were surprising and had the potential to save $20,000 over the life of the mortgage $643/year = Cost of air leakage at 7/m3/m2/h - N 50 of...