Old Home Superhome visits April 1st-3rd

39 Hawthorne Rd
Bournville B30 1EQ

Open house with 50 minute tours:
Friday 1st April 2pm - 6pm
Saturday 2nd April 10am - 4pm
Sunday 3rd April 1pm - 5pm

Book to visit online at
www.sustainable-energyacademy.org.uk/superhomes/
or phone 0121 475-2088

Read on to see how Chris and Harriet reduced their energy use by 85% and saved 6,300 kg CO₂

Chris and Harriet Martin purchased their 3 bedroom, 1932 semi-detached house in 2009 and immediately set about ways in which they could improve its energy efficiency. They were motivated to do so by a "deepening concern for the effects of our profligate energy use on the environment".

As active Cotteridge Quakers, they had been involved in renovating their meeting house, reducing its energy use by 90%. This success, combined with a desire to downsize, gave the Martins the motivation, knowledge and skills to find a new project to work on, and so they took up the challenge of 39 Hawthorne Road. By acting as an exemplar house, they hope to "empower others by sharing the experiences and understanding gained in the process"

Insulation is the key to energy saving. The cavity walls are filled with polystyrene balls. Additionally they are lined internally with 55mm of Thermoline insulation board bonded to plasterboard. In consequence the walls' U value (and heat loss) dropped 89% from 1.7 to 0.2.

The loft contains an unheated storage room which has 160mm of thick foam blocks (U value 0.2) fitted beneath it. The remaining area has solid insulation blocks underneath the loft floor (U value 0.2), Where there is no flooring, the old insulation was topped up to 400mm with fibreglass (U value 0.1). Under the downstairs wooden floors foam blocks were inserted between the floor joists (reducing the floor U value 95% to 0.2). The central heating pipes were positioned just below the floor joists so that any excess heat comes up through the floor.

The pre-existing windows were wooden framed with single pane glass and were extremely draughty. By replacing them with A rated double glazed argon filled UPVC windows, the U value has dropped from 5 down to 1.2, reducing window heat loss by 75 %.

In addition, the unheated conservatory which replaced an old extension benefits from passive solar heating and collects any heat lost from the house. The floor's dark brown floor quarry tiles maximise absorption of solar heat. Over the winter temperatures inside vs. in conservatory vs. outside were in the ratio 6:3:1 (e.g., 18C inside, 9C in conservatory, 3C outside). Its A rated double glazed units considerably reduced heat loss.

Finally, the front door was replaced, reducing the U value (and thus heat loss) by 64% from 3.6 to 1.3.

Renewable energy systems are incorporated right through the Martin's house. Solar thermal panels (Worcester Bosch Greenskies) are in place on the back roof. The house is on the Bournville Village Trust which does not allow solar panels if visible from the road. In consequence the panels on the back roof face west, not south, reducing their efficiency by 5% (according to the Encraft SAP 2009 Solar Thermal Calculator).

On a sunny summer day the panels can heat the 180 litre water cylinder to 53°C. Our Wickes eco bath saves 40% and the Mira eco shower-head saves 64% on our hot water usage.

In order to make space for solar PV panels, the Martins constructed a south facing pergola at the bottom of the garden. 10 PV panels are fixed to its roof with an output of 1800kWh per year - an output that matches their annual use. What they don't use is fed back into the national grid. They receive a Feed-In Tariff of 41.3p for every kWh generated, whether they use it or not.

The pre-development boiler dated from the 1960s would have been at best 68% efficient. The back of the boiler protruded into the unheated utility room covered only with a sheet of asbestos, resulting in considerable heat from the house. The new boiler is a Worcester Bosch Greenskies boiler with over 90% efficiency. All the radiators are fitted with thermostatic radiator valves meaning each room can be controlled separately. The thermostat is set to 18C; the house is occupied all day. Bedrooms have radiators, but are set low and normally unheated in winter.

In addition, a smokeless wood burner has been installed in the living room. It is specifically designed from smokeless zones and burns at 80% efficiency. It is a vast improvement on its predecessor, an open fire burning at 30% efficiency which was legally only able to burn a smokeless fossil fuel. With a fire smouldering all day the wood burner seems to generate about 10 kWh a day (about 25% of gas usage on a cold day).

Further to insulation and renewable energy systems, the Martins have made use of several energy saving appliances.

The whole house makes use of energy saving lighting. A Megaman candle bulb greets visitors in the hallways, with 18W energy saving lamps in the study, low energy bulbs in the living room, 5W LED bulbs in the kitchen (using just 10% of the old halogen bulbs energy consumption). There are Megaman spot light in the dining room and a 20W LED spot light for the patio and garden.

Their white goods all have very high efficiency ratings, with an A+ rated washing machine, dishwasher and fridge, plus an A rated freezer. Low flush toilets and water butts in the garden (like the eco bath, toilets and shower mentioned earlier) have helped reduce our water use to c. 100 litres daily each (66% below UK average). Clothes are line dried, in wet weather in a drying area under the pergola. A key factor of becoming energy efficient is to cut wastage, and introducing such everyday measures as these makes a significant contribution.

Energy use from 1st July 2010, when the Martins moved in, up to mid February 2011 suggests they will save 85% of the energy used in a similar (but un-insulated) house with no solar panels. They are on course to pay for all their year's heating with their old age heating allowance.