The house uses the FutureForm construction methodology to create a Passivhaus shell topped by an unheated winter garden, achieving up to level 5 of the Code for Sustainable Homes. The house can be assembled as semi-detached pairs or as extensive terraces in three-plus-one and four-plus-one storey configurations and in forward and rear entrance modes to suit site demands. Using a combination of passive solar, solar photovoltaic (PV) and optional roof-mounted duct-augmented or vertical axis wind turbines, it can connect to district combined heat and power and/or to the national grid.

Planning considerations
In any development, the E Howard House faces north-south. The ideal layout has the terraces arranged along one-way streets with main roads connecting these between gable ends. The front of one terrace faces the rear of the next with pavements and cycleways between. Larger trees are planted against the northern façades to enhance privacy. High densities are possible with no loss of sunlight to living areas or roof gardens.

All houses take into account Lifetime Homes and Access For All requirements. A Part M compliant rack and pinion lift replaces the additional storage rooms as the needs of residents change. The stairwell landings are set at 1500mm depth to facilitate this. All staircases meet ambulant disabled requirements and all thresholds are level.

At ground floor level there is a porch, cloakroom and office/spare bedroom in addition to the garage, which is 3300mm wide to assist car use by the mobility impaired. At first floor (and at second floor in four-plus-one storey configurations) are the bath/shower rooms and bedrooms. The latter contain deep curl-up-and-read window bays. At second floor is the open plan cook/dine/live area (in four-plus-one configurations an additional communal room can replace one of the bedrooms on the second floor).

There is a 1900mm deep, south-facing and protected balcony.
At third floor is the unheated winter garden (which lies outside the thermal envelope of the house), and the plant room.

Urban food production lies at the heart of this design: the greenhouse provides a perfect environment for vegetable and fruit growing. A gangway across the roof connects all terraces and provides access to wind turbines, and is a platform for roof maintenance.

Construction
Each floor divides lengthways into two sections for manufacture and transport. Construction uses micro-piles and a steel ring beam in an excavated footprint (ground conditions permitting) to reduce construction times. The framing for the shell is a standard FutureForm system, with triple-glazed windows and a polished zinc rainscreen. The over-roof is a steel portal frame with toughened and laminated single glazing to the conservatory. Gable end walls are clad in either ceramic panels or lime-mortared brickwork.

Energy in use
The house uses high levels of thermal insulation and airtightness to achieve the Passivhaus standard. Energy use is monitored and controlled by a plant room building management system. Passive solar gain through the southerly façade heats air that is mechanically drawn through the habitable rooms from the top of the stairwell (enhanced by natural stack effect). Warm air is also drawn directly from bathroom and kitchen locations via the full height ducting behind these areas. Exchangers in the Plant Room mechanical ventilation with heat recovery (MVHR) unit transfer this heat to incoming fresh air drawn from high level on the northerly façade (in winter) or to water in the thermal store (in summer). Fresh air, preheated as required, is ducted through habitable room floors. There is no further space heating.

The house is all electric, and future-proofed against growing shortages of fossil fuels. It uses a 50 per cent PV fritting pattern to all non-habitable area glazing (stairwells and winter garden) providing in the region of 70m2. For appropriate sites each house can also have two duct augmented or vertical axis wind turbines mounted on the portal roof frame, with inverters and batteries mounted in the plant room. The house can supplement district biomass combined heat and power in larger developments or can trade against the national grid.

Low-energy demand fittings, including induction hobs, are standard. There is a charge point for an electric vehicle in the garage. Some 7m2 of evacuated tube solar collectors above the stairwell combine with the heat exchangers in the plant room to lower demand on the electric boiler, which is coupled to the thermal store.

Water in use
Rainwater is harvested. From the northern slopes the water channels into a grey water tank in the plant room for toilet flushing and washing machine use. From the southern slopes it is stored in a water butt at ground floor level for garden use. Water demand is further reduced by controlled tap and shower fittings. In developments with extensive garden allocation, composting toilets supplant those used in higher density developments.

Stormwater is managed by extensive sustainable urban drainage systems beneath permeable paving to the driveway and throughout the scheme.

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