The standard for the buildings we already have.

EnerPHit is the Passive House Institute standard for deep retrofit of existing buildings. The full Passivhaus standard assumes you can design the fabric from scratch; existing buildings rarely allow that, because of their structure, party walls, heritage status or site constraints. EnerPHit applies the same building physics to what you already have, with criteria relaxed just enough to be achievable on a real existing building while still delivering very low heating demand, comfort and a certified result.

EnerPHit can be certified by two routes. The component method sets a U-value and quality criterion for each element of the envelope. The energy demand method caps annual space-heating demand (25 kWh/m²a in the cool-temperate climate that covers Ireland and the UK, adjusted by climate zone). The airtightness target is 1.0 air changes per hour at 50 Pa, against 0.6 for new Passivhaus, recognising that an existing structure cannot always be sealed as tightly. We advise on which route suits your building before any design commitment.

Yes. The EnerPHit Retrofit Plan (ERP) lets you certify a phased retrofit: a single coordinated plan that sequences the work over years or budget cycles so each step is done correctly and in the right order, without a later phase undoing an earlier one. This is how most occupied housing stock and public estates realistically reach the standard, and it is exactly the kind of plan that protects an asset owner from paying twice.

This is the real risk in any deep retrofit, especially where insulation goes on the inside of a solid or heritage wall. Adding insulation changes where the structure sits relative to the dew point, and a detail that is wrong can trap moisture and cause decay or mould. We run hygrothermal analysis (WUFI dynamic modelling and Glaser steady-state to BS EN ISO 13788) on the critical build-ups so the retrofit is safe for the fabric over its life, not just efficient on day one.

It is one of the strongest answers available. EnerPHit delivers warm, dry, well-ventilated homes with controlled humidity, which is precisely what Awaab’s Law is driving social landlords toward on damp and mould. Mosart has applied the standard to social housing retrofit, including Rochestown House in Dún Laoghaire. Paired with our Pulse monitoring, a landlord can also prove the homes are performing and evidence compliance continuously.

For an asset you intend to hold, usually yes. A standard retrofit often improves the energy rating on paper while leaving comfort problems, cold spots and a performance gap in place. EnerPHit is a whole-building method that closes that gap and is independently certified, so the improvement is real and verifiable. We will tell you honestly at feasibility whether a building is a good EnerPHit candidate or whether a lighter intervention makes more sense.