Private Client - Harpenden - As featured on the Passvhaus Trust website (Award Finalist) 

Deep retrofit of a 1960s detached house in Harpenden and the addition of a small rear extension.

This project is certified as meeting the EnerPHit Plus (Passivhaus) retrofit criteria, the third such project in the UK, and is 'gas free', using an air source heat pump and harnessing renewable energy with an entire roof pitch dedicated to solar pv. 

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The existing brickwork walls were externally insulated using wood fibreboard and finished with a painted render and the curtain walls were removed and replaced with new highly insulated timber I beam walls with cellulose insulation and clad in larch. The rear single storey extension was also constructed in this way and finished with either render or timber cladding. The existing ground floor was removed and replaced with a new highly insulated slab with underfloor heating. 

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See the press information below.