It’s not correct to say a Low Energy Building (LEB) is a Passive House. Yes, it is a PHI standard. But to claim it is a Passive House, as a real estate agency’s media release did last month, is going too far. Yes, LEB is a building certification awarded by the Passive House Institute but it is confusing to conflate LEB and Passive House certifications.
However the two differ by degree, not substance. Compared to a Passive House, a LEB
- may use up to twice as much energy (up to 30kW/m2/a vs 15kW/m2/a for a certified Passive House)
- is not as airtight (up to 1.0 vs 0.6ACH); and
- is not modelled for thermal comfort (this means it may feel slightly colder sitting by a window on a winter’s day. In a certified Passive House, there would be no noticeable difference in temperature anywhere in the room).
The reasons for the difference in performance will vary on a case-by-case basis. Sometimes the same construction methods and materials are found in a LEB compared to a Passive House project but form factor or other constraints mean the building doesn’t hit the PH targets. In other New Zealand LEB-certified homes, budget constraints meant less insulation and more affordable windows and doors were specified, with a subsequent impact on thermal performance and energy efficiency.
However, a LEB is a MUCH better house than one built to the legal minimum standard (ie the NZ Building Code) and for reasons I wrote here, we should celebrate every one of them.