The amazing thing about Comfort-Haus is that it doesn’t need a boiler. It has no radiators, no underfloor heating or air conditioning, yet it stays warm in winter and cool in summer. With insulation three times better than current building standards and air-tightness 14 times better than building regulations, the heat from people, appliances and the sun are retained in the building to maintain a comfortable year-round temperature.
Comfort-Haus has been designed to allow communities to grow and evolve. It is easily adaptable to changes in its occupant’s requirements and allows people to grow old among their lifelong friends. The whole ground floor of Comfort-Haus can easily be converted into an autonomous “granny flat” with a carer accommodated above, so that families and communities can remain intact.
There is extensive opportunity for alterations to internal layouts:
- The floor slabs allow openings to be formed through floors so that lifts or hoists can be installed.
- The ground floor WC is fitted with additional plumbing and drainage to allow for the later inclusion of a shower.
- The house comes with a garage suitable for a large family car. However, alternative configurations allow for a larger garden space with a garage that can accommodate a Smart car and several bicycles.
- The home-office space on the second floor landing can be converted to a fourth bedroom.
Comfort-Haus has three large bedrooms with a spacious “great room” on the ground floor. It has been designed to take advantage of daylight so that the need for artificial lighting is reduced. It is also ideal for natural ventilation in summer.
A domestic sprinkler system avoids the need for fire lobbies, which take up valuable space.
External bin stores house domestic waste in recycled waste containers and compost bins.
The exterior of the building is finished with ventilated larch weatherboarding treated with breathable coloured wood stains to limit maintenance.
Energy conservation is the key to the comfort of Comfort-Haus. High levels of insulation and air-tightness eliminate the need for heat sources while a comfortable temperature is maintained all year round.
Several structural features make Comfort-Haus different from ordinary houses:
- The structure sits on an insulated concrete foundation slab formed using ground granulated blastfurnace slag (GGBS) cement (a recycled by-product of steel manufacturing). GGBS cement reduces the CO2, NOX and SO2 emissions of concrete by 70% and reduces the embodied energy of the concrete by 40 per cent.
- The structural walls and floors are constructed from 150mm-thick panels of KLH cross-laminated timber formed from small sections of sustainably grown wood.
- The external walls are insulated with 250mm of Pavatherm wood-fibre insulation. This provides excellent insulation against winter cold, summer heat and noise.
- The roof also uses KLH cross-laminated timber panels and 300mm of Pavatherm insulation.
- The roof and walls have a U-value of 0.12W/m2K, which is three times what building regulations require.
- This low cost, simple construction of cross-laminated timber panels, wood-fibre insulation and larch weatherboarding also creates a store of 35 tonnes of CO2.
- The house is fitted with Bayers’ Eco-Therm triple-glazed windows with average U-values of 0.73W/m2K, which exceeds current continental Passivhaus standards. Careful window installation creates an incredibly airtight structure (<0.6 air changes per hour) that is 14 times better than current building regulations.
- A heat recovery ventilation system in the roof void uses residual heat from bathroom and kitchen extract air to preheat fresh air supplied to living spaces. The HRV system combines with the high level of air tightness to prevent the loss of heat through drafts while maintaining a supply of fresh air to the benefit of the occupants health and comfort.
- A 300-litre rainwater harvesting tank beneath the garden provides water to the 6-litre dual-flush toilets, washing machine, sprinkler system and external tap for garden watering.
- All domestic appliances are specified to at least an A rating under the EU Energy Efficiency Labelling Scheme.
- All light fittings are low voltage and energy-efficient.
- The secluded garden provides a private external recreation space which can be used for clothes drying. This eliminates the need for tumble driers.
- An internal airing cupboard on the second floor is located over the solar hot water tank. The slatted floor allows residual heat from the tank to dry clothes in bad weather.
- All timber specified is to be from Forest Stewardship Council accredited sources.
- All materials and finishes are specified to at least grade B of the Building Research Establishment’s Green Guide to Housing Specification.
Designed to zero-carbon principles, Comfort-Haus also incorporates a number of features to limit the community’s demands on external energy generation:
- A Viessmann ‘Vitosol 300’ 3m2 evacuated glass tube solar panel provides at least 65 per cent of the house’s hot water requirements thoughout the year.
- Integrated within the roof are 35.2m2 of Solarcentury’s C21e photovoltaic roof tiles. These tiles will provide approx 3500Kwh of electrical energy per year (compared to expected demands of 3300Kwh for an average family).
- A ground source heat pump is used to supply top-up heating to the warm fresh air from the heat recovery ventilation unit.
The house is expected to achieve a Code for Sustainable Homes score of over 70 points and a level 6 rating.