MVHR is a whole house system that extracts air from wet rooms while supplying fresh, filtered air into habitable rooms.
- It must meet the whole dwelling ventilation rates set out in Table 1.3
- The heat recovery minimum efficiency has increased from 70% to 73%
- The extract airflow must match the supply airflow to create a balanced system.
- It must be installed by a competent person (SAP benefit as of 2010)
- The ductwork must be designed to minimise the overall length and to reduce the number of bends required.
- Ensure an appropriately sized duct has been installed for the air flow rate needed.
Number of rooms | 2013 edition | 2021 edition | Increase |
|---|---|---|---|
1 | 13 l/s | 19 l/s | 46% |
2 | 17 l/s | 25 l/s | 47% |
3 | 21 l/s | 31 l/s | 47% |
4 | 25 l/s | 37 l/s | 48% |
5 | 19 l/s | 43 l/s | 48% |
A significant change to Part F is that the ventilation rates of the whole dwelling have been increased.
A minimum ventilation rate of 13l/s should be used if a dwelling has one habitable room.
For each additional bedroom, add 6l/s to the 13l/s minimum requirement.
Alternatively, the whole dwelling’s minimum ventilation rate should be 0.3l/s per m² of internal floor area.
