Does your building need pressure testing?
Any new houses built under the new regulations will require testing before occupation. The Building Control will determine the to be testet dwellings. The sample size depends on whether ‘Robust Details’ have been used:
• If Robust Details adopted, test of each dwelling type one on each development. At failure, carry out improvement work an repeat testing procedures for the failed building, but aditionally also another building of the same type, located on the same development.
• If no Robust Details have been adopted, the number of tests to be carried out is to be determined by the following rule:
• Four or less dwelling types - test one of each
• Five to Fourty types - test 2 of each
• More than Fourty types - test Five percent of each. For every type, this can be reduced to 2% if the first Five pressure tests are passed..
| No of dwellings of one building type |
Amount# of air tighness tests to be carried out on each kind of building |
| 1- 4 | one test for all dwelling types |
| 5 - 40 | two pressure tests of all dwelling types |
| 41 or more | A minimum of five percent of all building types, unless the first five units of the tested type achieve the Design air permeability, the sampling frequency can be reduced to 2% |
Developement projects of two or fewer dwellings then a figure of 15 m³/m²/h can be used for the DER calculation and no testing is needed.
If the same contractor has built the same design within the preceding twelve months and can prove a compliant test result then no test is required either.
Blocks of Flats have to be considered as separate development projects, independent of number on the same site.
TER:
The TER is the Targetet Energy Rating.
DER:
The DER is the calculated CO2 emissions (kg/m² floor area) calculated using SAP 2005
Values:
The TER building assumes a q50 (air leakage) value of 10.0. If you use this as your design value (a cautious approach) the ventilation heat loss from your dwelling will be much the same as for the TER dwelling. As you have failed to deliver a 20% improvement here you will need to make it up somewhere else. If you proposal is a one or two dwelling development and you claim exemption from testing you will have to use a q50 value of 15.0, i.e. your ventilation heat loss will be significantly greater than that from the target dwelling. Making up for this is likely to be very challenging. The rationale behind this is fairly obvious: the ODPM does not want to encourage developers to claim the exemption, also human nature being what it is, it is very possible that quality control on site might be lessened when it is known that no test will be carried out (and vice versa).
BRE Survey of dwellings built to L1 AD 2002 (PDF) : Pressure testing a sample of dwellings gave the following results: Flats; range 3.2-12.4, mean 8.0; Houses: 5.6-16.7, mean 9.8