An air leakage rate of 3.7m3/h/m2 at 50 pascals, quoted in 'Building an airtight case' (aj 20.4.00), is good compared with the average new building in the uk. However, it is easily surpassed by other uk buildings, such as the contemporaneous house at Twyford with an air leakage rate of about 1.0m3/h/m2.
Elsewhere, standards have moved on. In continental Europe, we have seen social housing, speculative developments, private houses and commercial buildings constructed to the European 'Passive House Standard', with air leakagerates of 0.6m3/h/m2 or less, at 50 pascals.
This specification is essential for such buildings, which are so energy efficient that they do not need a central heating system.