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film set of a futuristic city. But it is here now and demonstrates the extraordinary potential we have to reduce our carbon emissions today.

      Changing light bulbs can yield yet more savings – in fact the International Energy Agency estimates that we could save 10 per cent of our global electricity bill by switching to energy-saving light bulbs. Each 100 W bulb replaced by a compact fluorescent light (CFL) bulb will save up to 38 kg of carbon dioxide a year – and will last 12 times as long. Incandescent tungsten filament light bulbs are to be phased out by 2011 and LEDs (light-emitting diodes) could become 80 per cent efficient in the future. Simply switching off the lights can make a difference too. Research has shown that we waste £180 million worth of electricity by leaving lights switched on – and 770,000 tonnes of carbon dioxide a year.

      If we were more aware of how much energy we were using, the chances are we would use far less. So, rather than hiding the electricity meter away under the stairs, putting it on display can help save energy, cutting electricity consumption by between 5 and 15 per cent. Households can install free meters as part of a government-backed trial and there’s an increasing number of canny gadgets to keep you on top of your home’s electricity use.

      top tip

      The Energy Performance Certificate (issued by an Energy Assessor) is a major part of the new Home Information Packs (HIPs) which are now required in England and Wales when you sell your home (right). The certificate shows your home’s energy efficiency rating from A (most efficient) to G (least), and its environmental impact (CO2) rating as well as advising how both of these can be improved.

      save to spend

      It’s a curious thing: although there’s huge potential for saving energy in our homes, offices and industry, evidence suggests that energy savings can, perversely, lead to more energy use.

      A theory known as the Khazzoom-Brookes Postulate describes how, in a free market, increased energy efficiency results in cheaper prices – so consumption increases. Add to this the fact that companies take advantage of savings by spending the money elsewhere. Halve your gas bill and you have extra cash to spend on other things, which are likely to have their own carbon price. This is known as the rebound effect.

      Energy efficiency is good for householders and for business. It means that more can be done with less. It also means that people who previously could not afford to have warm homes, may now be able to. But if the end result is an increasing demand for energy, this could mean more carbon dioxide emissions.

      Not everyone agrees with the Khazzoom-Brookes Postulate, and there is evidence to suggest that the rebound effect is small compared to the total amount of energy and emissions saved. But the theory sounds a warning. Being more efficient is the first, necessary step. But we need to make sure the savings are invested in further efficiencies.

      the art of the possible – the energy-saving house

      Six low-energy homes are being built at Nottingham University as part of a teaching project run by the university’s School of the Built Environment.

      Reducing energy demand was the starting point for the houses. But it was also crucial, for the purposes of the demonstration, that they did not cost more than conventional properties.

      Five of the six houses were designed with different building methods and the latest energy-saving technologies – an upgrade of a 1930s house would complete the project. When the homes are finished, students or staff of the university will live in them, and their energy use will be monitored continually via a website.

      Dr Mark Gillott, project leader, explains that making the homes desirable was crucial: ‘We wanted to give the houses a wow factor when people walk in. We want people to think “I want to live in this house.”’

      Innovative building techniques are key to making the homes affordable. A four-bedroomed family house – the first property built – uses a lightweight recycled steel frame, rather than bricks and mortar, but with its pitched roof, looks like a conventional home. The frame, which took less than five days to put up, is insulated with plasterboard designed to absorb and give out heat. Savings in construction time and labour costs meant more money could be spent on the latest technologies to generate and conserve energy.

      The foundations use an insulated concrete framework; but rather than conventional concrete this is made primarily from ground granulated blast furnace slag – a byproduct of the iron industry, which produces a tenth of the carbon dioxide emissions produced in the manufacture of Portland cement. Good design and renewable technologies combine to provide power and heat. An underground pump channels warm air (11-12°C) into the south-facing conservatory on the ground floor of the house, where it is warmed by the sun, and then pumped into the rest of the house.

      In the loft a ventilation and heat-recovery unit converts solar energy from roof-mounted panels to produce hot water and warm air for under-floor heating. South-facing windows are triple-glazed and have blinds and external louvres to stop it getting too hot in summer. Balconies add to natural shade.

      Smart energy controls allow the house to respond to changes in the weather – or to be controlled remotely via a website or a phone line. Appliances are all energy-saving models and lighting uses highly efficient light-emitting diodes (LEDs).

      A water-saving system uses rainwater for the outside tap, washing machine and downstairs shower; and water from the bath and shower for flushing toilets. Aerators in the shower fittings increase the water pressure, and sensors on tap fittings ensure they are only used when needed.

      Dr Gillott says, ‘It’s designed so that there’s plenty of daylight, and it’s a warm and comfortable place to be in winter and ventilated and airy in summer.’ Good design, he emphasises, is crucial. ‘It’s what we say to the architecture students all the time. Don’t leave it to the engineers to bolt on solutions afterwards.’

      Two of the five new-build properties will cost under £60,000 and Dr Gillott hopes one of these will achieve zero-carbon status. ‘There are no barriers from the technology to say that we cannot generate all the energy we need. There’s no reason why we can’t generate a zero-carbon home,’ he says. ‘The question is whether the industry will embrace it quickly enough to achieve it. Really, it is only legislation that can make the difference.’

      the workplace

      Just as big energy savings could be made in the housing sector, we can also smarten up the carbon impact of the workplace – whether that’s a major corporation, government building or a home study.

      Energy-efficient buildings play an important role. Good design can, for example, make the most of natural light and provide shade from too much sun. Here are three examples:

      A recent Royal Navy building in Arbroath uses thermal heat stores and sunpipes to make the most of natural warmth and daylight in an energy-efficient office building for the Royal Marines.

      The Swiss Re building, affectionately known as the gherkin, was designed as ‘London’s first environmentally progressive working environment’, making use of natural light and ventilation, with an extracted air cooling system.

      A Tesco store at Diss in Norfolk is designed to use 20 per cent less energy. Small steps such as adding doors to chill display units can make a huge difference to a supermarket’s energy use.

      For what you can do in the workplace, turn to Chapter 9.

      PRETTY PICKLE:

      London’s iconic Gherkin reveals how architects can combine cutting-edge design with environmentally advanced features to reduce

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