The Air Tightness Testing and Measurement Association, ATTMA, has released an update to ATTMA Technical Standard L4 (TSL4) – Measuring Air Permeability in Passivhaus & Low Energy Buildings – Fan Pressurisation Method.
This minor update amends the changes to the AECB building standard by providing details on the 3 levels that are now in the standard. This can be found on Table 1 on Page 5 and as seen below
| Ventilation Strategy | Target Air Change Rate N50 |
| Passivhaus Standard | ≤0.6 |
| EnerPHIT Standard | ≤1.0 |
| PHI Low Energy Building | ≤1.0 |
| AECB CarbonLite Standard Level 1 | ≤5.0 |
| AECB CarbonLite Standard Level 2 | ≤2.0 |
| AECB CarbonLite Standard Level 3 | ≤1.5 |
The updated standard can now be downloaded through the ATTMA website, and has also been updated in the combined technical standard folder.
If you have any queries, contact Paul Carling, ATTMA Technical Manager on paul@bcta.group or 01494 358 159
