We are working on an increasing number of projects targeting the Passivhaus and EnerPHit low energy building standards. We use the Passivhaus standard for new build homes and the EnerPHit standard for work to upgrade the performance of existing buildings. 

EnerPHit is the slightly less challenging standard for the retrofit and refurbishment of existing buildings, where achieving the passivhaus standard is not technically (or perhaps financially) feasible due to the nature of the existing construction.

Achieving the EnerPHit standard usually requires deep retrofitting of the building, and our process begins with an analysis of the existing building and modelling of the possible strategies for the retrofit (Building Fabric Retrofit Analysis).

The analysis shows the impact of taking different measures, which allows a more targeted approach and takes into account the unique nature of each project. The existing building's location, orientation, construction and design all effect how a retrofit could best be approached. In addition to these factors, it is often the case that clients want to undertake a retrofit project as part of a larger extension or refurbishment of their homes. Sensible sequencing of works therefore also comes into play when deciding what work to tackle now and what to do later.

There are a number of reasons that the EnerPHit standard can be challenging to achieve in the course of one set of works, for example if a client has relatively new double glazing and does not want to change this in the short term for triple glazing. In acknowledgement of this, the passivhaus institute has created multiple routes to compliance.