Member Project: Hawkhurst
The developer members of the GHA have all committed to building fully sustainable homes and communities in accordance with the GHA Standard and Charter in the majority of their developments, and to higher standards wherever possible.
GHA Developer Member:
Town and Country Housing Group appointed Cowan Architects to design the scheme and asked Calford Seaden to provide specialist consultancy and energy assessment in addition to their role as Employer's Agent. The design approach to the project has been one of integrating environmental principles and technologies with traditional forms, with the intention of producing a sustainable building that is appropriate to the area in a contemporary manner.
The environmental approach relies on a high level of thermal insulation and airtightness, with 350mm thick walls. These, combined with heat recovery from ventilation air and use of solar gains, reduce the energy required to heat the building.
The building is closely oriented to the points of the compass, with the South-facing roof pitch incorporating 23 sq/m of photovoltaic tiles to supply all of the necessary electricity. A further 3 sq/m of solar hot water tiles and a heat pump will meet the demand for heating and hot water.
To meet the required energy target the Hawkhurst 'Zero Carbon' 2 bedroom home will need to be very airtight (90% more so than the minimum Building Regs requirement) and so we will be using a carefully selected ventilation system which will actually filter the air of allergens and toxins and prevent any condensation. This should have significant health benefits for the occupants.
The scheme will engage with and demonstrate best practice not only in energy consumption in use, but against the wider agenda of Sustainability, in meeting Code for Sustainable Homes - level 6. The ambition for responsible use of resources extends from the selection of building materials 'V the energy embodied in them in manufacture, transport to the site 'V through to the reduction of waste during construction, and potential for toxins to leach out in use; the whole lifecycle in other words. For example external timber cladding is intended to be Sweet Chestnut, coppiced from Kent and Sussex woodlands, and manufactured in Sussex. The way the building and its occupants impact on the environment is weighed against other criteria too, such as reducing water use and storm water runoff, waste reduction and recycling and the protection and enhancement of local biodiversity.
Standard:CSH Level 5 - achieved Level 6
Walls to be 350mm thick to achieve high thermal capacity (U - V value < 0.15 w/m2/K) using either Celcon aircrete thin bed blockwork or high performance timber frame (tbc) plus Terranova 'Eco' bricks
Lifetime Homes compliance
Roof to use naturally sourced clay tiles
Integrated solar thermal (hot water) tiles on the roof
Integrated solar photovoltaic PV tiles on the roof - V 23sqm
A ground source heat pump to provide heating and top up hot water
An airtightness rating of 1
A highly efficient mechanical ventilation and heat recovery system
Triple glazed timber windows
A grey water recycling system
A rainwater harvesting system
Low flow rate shower, low flush WC and flow rate restrictors on taps
Low energy light fittings throughout
Natural (low toxin) paints
Internal & external recycling facilities
Maximisation of sustainably sourced and where possible local materials
'Passivhaus' principles introduced
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