PHPP states a target controlled air change of 0.3 ac/h. Assuming a ceiling height of 2.5m (default in PHPP) this is equivalent to 0.21l/s.m2 (of floor area) when converted into units for UK building regs - if my maths are right.
However, the building regs (Part F 2010) specify a minimum average controlled ventilation rate of 0.3l/s.m2 of floor area.
This means that the controlled ventilation being assumed for PHPP energy calculations is less than that required for the UK building regulations.
Is my maths right?
If so, then either I stick with the PHPP value, which means I am breaking the Building Regs or I go with Building Regs, which means my energy calculations in PHPP are optimistic and I need to factor in a larger MVHR system.
There is a get out in the building regs related to performance based ventilation but this seems complicated and difficult to prove.
What is the generally accepted approach?
I'm sure this is covered elsewhere, but I've done a search and not managed to find anything.