Before and After Design: Sustainable in Suburbia

At first glance it’s difficult to see evidence of the changes – implemented by architect Jerry Harrall – that have transformed this run-of-the-mill 1930s end of terrace into an exemplar low-energy home. However, introducing high levels of insulation, harnessing thermal mass and working with the house’s orientation have all helped to reduce annual fuel bills from £706 to just £166.

Like many builds of its period, the solid brick walls of this 1930s home were without insulation — so too were the roof and floors. Jerry responded by creating a superinsulated structure, insulating walls externally with 100mm of extruded polystyrene, finished with render.

Heat loss through the roof has been minimised with the addition of 600mm of mineral wool in the loft space, and 100mm of insulation has been added within the floors. The house’s average U-values have massively reduced from 2.24W/m2K to 0.37W/m2K as a result.

Inside, a concrete floor has been introduced, facilitating the house’s capacity for thermal mass — heat entering the home is now captured by this material and then slowly released when internal temperatures fall. Thermal inhibitors such as wallpaper, gypsum and plasterboard have been removed — replaced by wet plaster, which aids this process.

Jerry has also capitalised on the house’s orientation by increasing glazing on the south-facing rear — allowing heat and light into the home. The old rear timber utility room has been removed to facilitate passive solar gain, while lost floor space has been compensated for with the addition of a two storey extension. Furthermore, reducing glazing by half on the north-facing front elevation has significantly reduced heat loss.

Such changes have enabled Jerry to design out central heating, with heat from everyday activities and passive solar gain keeping this well-insulated home cosy. Low-energy electric underfloor heating and a woodburning stove do, however, provide back up in the colder months.

A 1,100-litre rainwater harvesting system completes the sustainable picture, providing water for outdoor use.

LOW RUNNING COSTS

1. Passive Ventilation (See Main Image)

Passive stack ventilation means moist, warm air from the kitchen, utility and bathroom naturally rises – via vertical ducting – and is released outside. This no energy approach is used in conjunction with trickle vents and passive cross ventilation (opening windows) which introduce fresh air.

2. Solar Power (See Main Image)

Solar PV (electricity) and solar thermal (for hot water) panels on the southfacing roof reduce this house’s reliance on energy from the Grid — cutting running costs and making carbon savings. The above example, Worcester Bosch’s Greenskies solar thermal panels, costs £3-5,000 to install.

Further Reading:

• Before and After Design: Renovating a Bungalow 
• Before and After Design: A Green Makeover
• Before and After: A Modern Makeover