|Brick-built family home|
... is a four bedroomed detached house built in 1954 by Doug Murray, the then city architect. There is an extension built in the 1990s. We have lived here since 1999. Since then we have tried to make improvements to the energy efficiency of the house. The idea has partly been to explore might be done with an ‘ordinary’ house to reduce its impact on the environment.
This is a four bedroomed detached house built in 1954 by Doug Murray, the then city architect. There is an extension built in the 1990s and the total floor area is around 140 m2. The house is situated in the Headington Hill Conservation area.
Annual Energy Usage
Electricity: Around 4000 kWhr per year imported (plus another 1300 kWhr generated on-site – some of which is exported back to the grid).
Net cost £330 (includes cooking).Gas: Around 10000 kWhr per year.
Cost around £230
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|About us and why we did it
We are a family of four: two working parents and two school-age children. We wanted to make our house more energy efficient and reduce our impact on the environment The idea has partly been to explore might be done with an ‘ordinary’ family house. We have found that a lot of people are interested in what we have done and we are keen to encourage others to make similar improvements. Since moving in we have reduced our net electricity use by 25%, our gas use by about 30% and water use by 25%.
One of the obvious features is the large photovoltaic array on the south facing roof. This is 12 m2 in area and rated at 1.5kW (peak). It was installed in 2005 by Chiltern Future Energy (www.chilternfutureenergy.co.uk). The cost was around £9000, but we received a government grant of £4200 towards this. The system generates around 1300 units (i.e. kWhr) per year, which is about 25% or our electricity use. We can’t use all of the energy on site (e.g. on a sunny day in the summer), and any surplus spills over into the grid. Thus, the reduction in the electricity that we need to buy is only around 1100 units per year. We do, however, receive 9p for every unit that we generate (even if we use it ourselves). Together with the reduction in imported units, the financial saving amounts to about £240 per year.
We buy the rest of our electricity from Good Energy, a completely renewable supplier (www.good-energy.co.uk). We import around 4000 kWhr, so the cost is around £400 p.a. before the rebate mentioned above. We have also bought shares in the Westmill Wind Farm Co-operative, which is installing five wind turbines near Shrivenham (www.westmill.coop). Our share of the electricity generated will be sufficient to supply the electricity that we use but cannot generate ourselves.
We have tried to minimise electricity use. Low energy light bulbs are used wherever possible. Ebulbshop (www.ebulbshop.com) is a good source of the more unusual ones. We have yet to find anything satisfactory for use with dimmers or to replace the 12v halogen lights in the kitchen. We have a Neff induction hob, which is much more efficient than conventional electric hobs.
In 2006 we installed a solar water heating system. This consists of 20 Thermomax evacuated tubes, together with a pump and larger hot water cylinder. The system was supplied by Solar Solutions Direct, a local company (www.solsol.co.uk), and cost around £3400. We received a government grant of £400 under the low carbon buildings scheme. The system provides nearly all our hot water during the summer months (April-September). During the winter the system still works to ‘pre-heat’ the water during the day before the boiler comes on in the evening to top up the temperature. Overall, about 70% of the energy required for our hot water comes from the solar system.
We have tried to economise on water usage and there are now water butts on the house and summerhouse which provide water to use in the garden. The 100 litre ‘slimline’ butt on the house is a good space-saving solution. This measure, combined with a new washing machine (when the old one wore out) and ‘hippos’ in the toilet cisterns have helped us reduce our water consumption by 25% to around 0.3 m3 per day. Our water bill is around £230 per year for a family of four.
The main heating comes from a condensing gas boiler, installed in 2000. There are thermostatic radiator valves on all of the radiators and an electronic thermostat which was installed last year. This is much better than the mechanical ones in maintaining an accurate temperature. We buy our gas from Equigas, which is a ‘fair trade’ supplier (i.e. it charges the same tariff to all customers, including those on prepayment meters - www.ebico.co.uk) The total gas bill is around £230 per year.
Another important factor is the design of the house itself, which has large south facing windows, so we benefit from quite a bit of passive solar heating, particularly on sunny days in the winter when the sun is low in the sky. We have thought about installing a ground source heat pump and the lawn is an ideal source of heat, but these systems are more efficient with underfloor heating (so that the temperature difference between the source and the heating elements is as small as possible). Our house has solid floors downstairs, so it would be expensive to install.
Cavity wall insulation was installed before we bought the house. We installed modern argon-filled double glazing with Pilkington K-glass (www.oxforddoubleglazing.com). We have recently upgraded the loft insulation to comply with modern building regulations (270 mm thickness). This was done using foil-wrapped insulation rolls (obtainable from Homebase), which are much easier to handle than unwrapped fibreglass.
We do have cars, but we try not to use them! Three of us are able to travel to work/school by bike and we try to use bikes for local journeys around Oxford. When the children were smaller we had a ‘U plus 2’ double trailer bike, which was great fun. Tess commutes to Abingdon two or three times a week. We have thought about getting an electric moped and would be interested to hear from anyone with experience of using one.
We grow some of our own vegetables in the garden, but most things are bought in. We use the Oxford Farmers Market and Fellers (the organic butchers in the covered market, who will deliver). Fruit and veg comes from Abel and Cole (www.abel-cole.co.uk) who deliver once a week.
We have compost bins for garden and kitchen waste and have recently bought a wormery for kitchen scraps. We are still learning how best to look after the worms, but you are welcome to ask to see them.
We try to use re-chargeable batteries for battery-powered toys and equipment. Battery force (www.battery-force.co.uk) is a great internet supplier and one often gets a free chocolate or sweet with each order! The UniRoss Hybrio batteries are particularly good as they hold their charge better than other NiMH rechargables.