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Passive house examples: cost breakdown

In this day and age anyone building or extending knows that a high level of insulation and airtightness have become practically mandatory. So we thought we’d break down the costs of two very low energy projects to show you just how much price variation there can be. In ROI, we bring you a detached two storey designed to PassivHaus standards with a high spec finish, costing approximately €1,700 per sqm (£132 per sqft). Supplied by architectural practice MosArt, The Phoenix Centre, Block 6, Broomhall Business Park, Wicklow, County Wicklow, tel. 0404 25777, www.mosart.ie.

BUILD SPEC

House size: 301 sqm / 3,240 sqft External walls: U-value 0.15 W/sqmK; blockwork cavity wall filled with EPS beads, plastered inside and out, total width 50.5cm. Floor: U-value 0.119W/sqmK; build up of 100mm concrete subfloor, 300mm phenolic foam insulation, 100mm cement screed. Roof: U-value 0.112 W/sqmK; build up of natural slates, batten & counter- batten, breathable membrane, 100mm fibreboard, 250mm cellulose insulation between rafters, airtightness membrane, 50mm mineral wool, gypsum & cellulose plasterboard 12mm. Windows: Triple glazed, argon filled, timber alu-clad, total U-value (frame and glazing): 0.8 W/sqmK, G-value: 0.55 Solar panels (hot water): Hot water demand: 5,930 kWh/year for six person occupancy; solar will supply 46% of this demand. Type installed: Vacuum tube collectors, 8 in total, collector area 6 sqm. Heat recovery ventilation (hrv): 91.3% efficient with average air change rate of 0.29 l/hr for total volume 750m3 (2.5m ceiling height x 301 sqm house).