Haringey Passivterrace
Green Building Store products specified for Retrofit for the Future project
Anne Thorne Architects LLP recently completed a Passivhaus-inspired refurbishment of an Edwardian, solid brick, mid-terrace property in the London Borough of Haringey. A 109m2 family house owned by the Metropolitan Housing Trust, the project’s approach was ‘Fabric First’, so high levels of insulation and airtightness were key parameters of the project.
Insulation was applied externally at the rear of the house and internally at the front of the house driven largely by external appearance and its location in a conservation area. Natural insulation has been used throughout the interior: sheep’s wool for the front of house and wood fibre on the party wall, to prevent heat being lost to neighbours. Chimney stacks were also filled with insulation. Due to financial constraints, external rendered polystyrene insulated panels were used for the rear wall; it was deemed more important for the internal walls to have natural insulation than the external walls due to breathability.
Green Building Store’s triple glazed Ecopassiv windows (Uw = 0.75 W/m2K) were specified throughout the project. Jennie Swain of Anne Thorne Architects commented: “We chose Ecopassiv because of its high performance thermally-broken frame, minimising heat loss at the window frame. The frame profile of the window also makes it suitable for installation in both externally and internally insulated wall retrofit situations, The use of FSC 100% timber was also an important factor. We had specified Green Building Store windows in past projects, so trusted the build quality and performance of the windows”.
Stringent airtightness was emphasised throughout, with airtightness layers including airtightness membranes to internal insulated walls, roof and floor, and plaster to external insulated wall with existing plaster parged where necessary. Airtightness membranes were pre-sealed to new windows and doors, following AECB gold standard details. A layer of continuous internal plaster to party walls links the building membranes within the walls, ceilings and floors, whilst a new triple-glazed internal lobby allows the existing Edwardian front door to be retained.
In terms of minimising thermal bridges in the building, vulnerable points were external wall insulation to internal roof & floor junctions, where the strategy was ‘to overlap’ insulation inside and out. Each thermal bridge was thermally modelled to ensure cost effective minimisation of thermal bridges, and allow the minimised heat loss to be used in energy calculations.
Primary energy target: Max. 90 kWh/m2/yr
Annual carbon emissions: 15 kg/m2
Completed 2011
Anne Thorne Architects LLP, Tel: 0207 729 6168, info@annethornearchitects.co.uk, www.annethornearchitects.co.uk
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