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Private Client - St Albans

A deep retrofit of a precast concrete-framed terraced house in St Albans and the addition of front and rear porches. This project was constructed to meet the PHI Low Energy Building Standard as well as going ‘gas free’ by using an air source heat pump and harnessing renewable energy with a solar pv array on the rear roof slope.


The existing gable and party walls were internally insulated using insulated lime plaster and woodfibre insulation and the concrete frame was externally insulated using woodfibre insulation finished with render. The curtain wall panels were removed and replaced with highly insulated timber I beam walls with woodfibre insulation and clad in metal weatherboarding. The concrete floor slab had a thin layer of insulation laid over the top and a retrofitted underfloor heating system. The roof was re-tiled and had 250mm woodfibre insulation laid between and over the ceiling joists.

Project Team

Contractor: Mars Building Group Ltd

ASHP: Solid Renewables

Windows and MVHR: Green Building Store/21°

Certifier: Mead Consulting


Project listing in Passive House Database 

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