Passivhaus Project: hybrid retrofit and new build extension

One of the UK's first Certified Passivhaus refurbishment projects

Retrofit element: conventional cavity wall construction with high performance external insulation; self-coloured render (wall U-value 0.10W/m²K)

New build element, using natural, breathable materials: Steico timber I-frame with woodfibre and sheepswool insulation, clad in UK sourced, FSC sweet chestnut cladding (average wall U-value 0.11W/m²K), living roof.

Totnes Passivhaus project statistics

Usable floor area (TFA): 162m² | form factor (ext. area/TFA): 2.62 | design space heating demand: 13.3kWh/m² per annum; heating load 9.3W/m²

Ventilation: Passivhaus Institute Certified heat recovery (MVHR), Paul Novus 300 with Lindab ducting

Air leakage: 0.2 air changes/hour on final airtightness test for Certification.

Windows: Internorm Varion/Varion 4, integrated blinds for summertime shading, installed whole window U-value from under 0.85W/m²K, g-value 0.6 on solar gain facades, double e-coated, argon filled.

Renewables: photovoltaics - Mobasolar panels, total 3.99kWp, Fronius IG TL transformerless inverter; solar hot water - Rotex 500 litre thermal store with 9.4m² of integrated roof panels

Construction cost (exc. VAT) per m² gross floor area: ca. £1400

Location:

South Devon

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