What is the EnerPHit standard?
The EnerPHit standard provides requirements for retrofit projects designed to maximise the thermal efficiency of the building and drastically reduce its energy consumption and heating requirements.
What's the difference between EnerPHit and passive house?
This article assumes that you are already familiar with the Passive House standard. If not, refer to our guide to Passive Houses
for an overview.
EnerPHit focuses on the same core criteria for the project as Passive House while accepting that meeting Passive requirements is generally not possible for a retrofit project. This is because important elements, like orientation and structural form, are already decided in an existing house.
To illustrate: if a building was originally constructed in a way that creates numerous areas of thermal bridging through its basic fabric, it will be challenging to eliminate them entirely. The stringent Passive airtightness requirement of 0.6 ACH will be equally difficult to achieve if the building was not originally built paying close attention to airtightness.
Other aspects of existing buildings that cannot be determined by the renovator include its form, orientation, conservation and planning restrictions, existing architecture and its position relative to neighbouring houses.
EnerPHit is designed to offer all the advantages of passive certification while remaining realistic for refurbishment projects. It will require more energy to achieve ‘Passive’ comfort levels in an EnerPHit home - but it still constitutes a considerable step up in energy efficiency from most existing homes; even from new builds.
Retrofit – a renovation of a building undertaken to significantly improve its thermal performance. Typically, this involves improving – or replacing - the building fabric, rather than simply introducing renewable energy systems.
Two Routes to EnerPHit
The EnerPHit-Standard can be achieved in one of two ways: through compliance with criteria for the building’s components - including interior and exterior insulation, high performance windows with low U-values, and ventilation requirements - or through compliance with the criteria for the energy demand of the building.
The energy demand method specifies a space heating and cooling demand of 25kWh/m2/year for Cool-Temperate climates (the EnerPHit standard graduates energy demand requirements by climate zones where the Passive does not; here we assume UK-based builders) compared to the Passive House standard of 15kWh/m2/year. This also includes limiting the percentage of hours with indoor temperatures above 25 degrees C each year (aka limiting overheating) to less than 10% without active cooling.
Sometimes, though, even if the highest performance components are used, the resulting energy demand is too high for the EnerPHit standard. This might be caused by the building’s fixed orientation, for example.
These cases are where the building component method comes in: if the building’s individual components can meet criteria as per the table below, the project can still be EnerPHit certified.
The component method requirements are summarised in the table below: