Whilst we support many of the underlying principle of Passivhaus design, we don’t believe that Passivhaus principle and design are the most suitable approach to retrofitting most of the UK’s buildings.  Essentially this is for the following reasons:

– Passivhaus compared to best practice standard eco renovation means lower gas and higher electricity loads due to the centralised MVHR.  Net this can lead to higher CO2 emissions

– Retrofit means convoluted ducting which means reduced efficiency. In addition whole house MVHR is not ideally suited to many occupancy models e.g. tenancy.

– The additional cost of achieving Passivhaus (on paper) is not usually cost effective when compared to the savings.

– There is usually a significant performance gap between Passivhaus modelling and in use figures.

Nethertheless, it is worth comparing our figures with those required for the different CarbonLite stages. As Carbonlite is focused on Passivhaus it necessarily expects a significant amount of the energy load to be for MVHR.  This means that the useful space heating energy requirement figure is low whilst the primary energy consumption figure is high. Click on the below to see the results.