Energy and SUSTAINABILITY Strategy - eastbridge
Minimum Heat Loss:
A 'fabric first' approach reduces heating requirements to a minimum. The houses are constructed from a super-insulated proprietary timber frame system with triple glazed doors and windows. Building junctions and cold bridges have been carefully analysed to reduce thermal loss further and the airtight design minimises heat leakage.
A balanced ventilation system ensures a high turnover of fresh air with a minimum of heat loss. Internal air is drawn from the kitchen and bathrooms and passed through a heat exchange to preheat the external air coming into the building.
The front door lobby also forms a buffer zone to reduce heat loss when entering and exiting the buildings in winter.
The Passivhaus approach carefully tests the size and orientation of windows. The large south facing glazed gable maximises the heat gain from the sun, while the window area is restricted on the north elevation to reduce thermal loss. Furthermore, the south facing glazed gable is set back from the elevation to provide shading in the summer, when solar gain is at it's most intense, but maxmises solar gain in the winter, when the sun is lower and the heating requirement at it's peak.
Integrated whole house heating:
A single integrated unit balances the ventilation, heating and hot water requirements of the building. It is likely that the solar gain combined with the heat created from normal usage (bathroom use, cooking, appliances, body heat) will provide the majority of the heating requirements. The ventilation system balances the heat sources and is designed to maintain a comfortable 20 degrees throughout the house, while the high turnover of of fresh air ensures an extremely healthy and comfortable internal environment.
The ventilation unit has a small integrated heat pump to provide hot water and supplementary heating if required. The only dedicated heating source is the electric underfloor heating in the bathrooms - while this is largely for comfort, it will also supply supplementary heating if needed.
The heating strategy is designed to be self-regulating, with simple and understandable technology - there is a single controller for the ventilation, heating and hot water. The houses do not require a primary heating source, radiators or a wet underfloor heating system, and there is no need for a separate external heat pump or ground source heating.
There is a 2.64kWh solar photovoltaic installation on each house, sized to match the energy demand of the heating, hot water and ventilation under normal efficient usage. The houses are connected to the mains electricity network, and the solar energy created will initially be used to meet the energy demand of the house and any surplus will be exported to the national grid.
The property will be eligible for the Feed-in-Tariff and the energy supplier will pay a set rate for each unit generated, plus a minimal export rate, however, these grants have been significantly reduced.
The houses will be equipped with an energy monitor detailing electricity consumption and generation. A simple colour system is used, glowing green when more power is being generated than used in the house. The monitor displays electricity usage in cost, watts or kg of carbon and comes with software to monitor detailed usage patterns.
The buildings are designed to ensure they are accessible and adaptable for homeowners in the long-term and as circumstances change. The design caters for wheelchairs users and individuals with reduced mobility, in relation to car parking facilities, external access, low thresholds, good access to entrances, doorways and hallways, ground floor facilities and window specification, amongst others. Furthermore, the store cupboards located near the entrance lobby have been specifically located for the installation of a lift if required in the future.
Sustainability in Construction:
The building materials were assessed against the Green Guide to Specification to ensure the wall and roof materials were rated to the highest sustainable level (A+).
The use of Modern Methods of Construction has created very high thermal performance and air tightness with minimum environmental impact. The insulation materials used also minimised environmental impact, with all products having a Global Warming Potential of less than 5, A low construction waste policy ensured a minimum of site waste to land fill.
Sustainable water management:
The bathroom and kitchen fittings, as well as the appliances supplied, have been designed to significantly reduce water usage, whileexternal rainwater collectors will further reduce the water consumption in the garden.
A shared package treatment plant ensures clean waste water is released into a drainage field, and all landscaping surfaces are porous, which, in conjunction with the use of swales, minimises surface water runoff and ensures a sustainable approach to water management.
PHI (Passivhaus Institute) Low Energy Building
Energy Performance Certificate 'A' rated.