Lake District passivhaus

Staveley Passive House 2

First floor walls: Eternit Cedral weather boarding on, 50 x 50mm vertical battens to form ventilated cavity, on Pro Clima Solitex WA wind-tight membrane, on 12mm Panelvent, on MBC 300mm twin stud timber wall with full fill cellulose insulation, on 12mm OSB with taped joints, The walls are finished internally with 50 x 50 battens to form service void insulated with Knauf glass wool insulation, on 12.5mm Fermacell board with Dulux Ecosure emulsion paint finish. (PHI certified). U-value: 0.110 W/m²K. Unfortunately the sub-contractors on site omitted to install the specified Pro Clima Intello Plus vapour control membrane assuming the 12mm OSB with taped joints would suffice. This goes some way to explain the marginal pass rate at the final airtest, when compared to other subsequent timber frame projects, where we have come to expect a result of 0.2 to 0.3ARC (at 50 Pascal’s) as standard.

Roof: bob-tail fink truss rafters at 600c/c with 620mm full fill Warmcel insulation, followed underneath by Pro Clima Intello vapour control layer/air tightness barrier, 25 x 50 battens to form a services void, 12.5mm drylining Gyproc board, Dulux Ecosure white emulsion paint finish. (PHI certified). U-value: 0.065 W/m²K. Unfortunately the sub-contractors on site failed to install the specified OSB ceiling board to support the loft insulation, so we had significant sagging of the air tightness membrane between the service battens, which made taping difficult.

Windows: Ecohaus Internorm KF410 triple-glazed aluminium clad windows and doors with ISO glazing spacers (overall U-value: 0.72W/m²K) were supplied and installed with air tight tape seals by Ecohaus to a very good standard. We certainly recommend a similar supply and install package on all our other PH projects to retain a single point of responsibility and high levels of quality assurance.

Passive and active solar design: A large percentage of the high performance solar glazing is orientated due south to the private courtyard back garden to obtain the benefit of passive solar gain to the living spaces. Shading prevents summertime overheating but permits low-level winter sun to penetrate to the heart of the house. Windows to the north, east and west elevations, that have less passive solar gain potential and are, in comparison, deliberately kept more traditional in scale and modest in size to reduce heat loss.

Solar hot water: one the largest consumers of energy within any house is the heating of domestic hot water to service the kitchen and bathrooms. As part of the sustainable development, 7.8m² consisting of 3 Consolar 27H flat plate integrated solar Panels are located on the south-facing roof of the house and are connected to an Akvatherm 500 litre  solar plus thermal store located in the centre of the house, off the landing.

Solar electricity: a 4kWp Solar photovoltaic integrated array, consisting of 16 Hyundai 250W modules are mounted on the south-facing roof of the house to convert sunlight to domestic use electricity and hot water via a immerse controller unit to transfer excess electric to the Akvaterm solar thermal store.

Low energy appliances: all appliances have been carefully considered to eliminate unnecessary electrical demand and to optimize the efficiency of the essential items (cooker, fridge, low energy LED lighting etc).

MVHR: in the winter months, when the outside air is cold relative to the required inside temperature, a Passive House Institute certified Paul Focus 200 whole house clean air comfort ventilation system is fitted with a 1kW electric supply duct heater, which includes the controller, programmable room thermostat and duct insulation (note: all of the supply ductwork was insulated with 50mm of foil backed fibre glass insulation. (heat recovery rate 91%.) All the duct work was installed by the local Cumbrian plumbing sub-contractor, who had little previous experience and the final installation was commissioned by the suppliers, the Green Building Store.  Tim and Sarah have the option to swap the heat exchanger with a ‘straight through’ module, a standard Paul accessory, which solves the summer over heating problem of the first year of occupancy.

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