Renovate or Rebuild: Which is Greener?

With mortgages in some parts of the country averaging ten times the annual salary, increasingly people are looking to buy a more affordable property and invest time and effort in improving it — and statistics are reflecting this shift to renovation. The number of home sales in June 2008 fell by a remarkable 80 per cent compared to June 2007, according to the Land Registry. But Lloyds TSB has seen a near 20 per cent jump in the number of borrowers wanting to improve their homes, while sales of renovation books and DVDs at B&Q have soared by 30 per cent. But is this a sustainable, eco-friendly option? Is it not better to demolish these old, draughty, energy-guzzling houses and replace them with new, high-efficiency homes?

Certainly, if the opportunity to knockdown- and-start-again exists, nine builders out of ten will advise doing so. The Government’s focus seems to be almost entirely on new build, with the Code for Sustainable Homes and Stamp Duty exemption on zero-carbon homes. We are told by the Government that we need 4 million new homes to be created in the next six years. That is an impossible target for even a buoyant housing industry. It means that many of the 6.3 million existing homes currently falling below acceptable standards will have to be upgraded. Halifax forecasts a surge in such improvements continuing at least throughout next year as the housing market continues a gently downwards spiral until 2010, as many pundits predict. So perhaps we need to think about this a bit more carefully.

The average existing three to four bedroom house with masonry cavity wall construction contains about 200 tonnes of new materials and 45 tonnes of embodied CO², according to the Bath University Inventory of Carbon and Energy. If we add a proportion for waste and CO² emitted during construction, the figures climb to 224 tonnes of materials and 54 tonnes of CO².

Renovation will save a proportion of that but, according to the Building Research Establishment (BRE), depending on the scale of the renovation, we may save as little as 25 per cent of the CO². An energy-efficient new build will emit around five tonnes per year, meaning that it would get back the CO² saving in just two years. In addition, a new energy-efficient timber frame house, built using mainly sustainable materials, will have embodied CO² below 30 tonnes; and if the materials in the original property are used in the new property – by recycling old pipes, using rubble as hardcore for drives, glass in the greenhouse, and timber for flooring or fencing – we still save that 25 per cent and have the energy benefits of a new home.

Then there is cost to consider. The BRE and the DTI (Department of Trade and Industry) have done some research into the issue and it is often a close-run thing. It depends on the extent of the renovation necessary to bring the house to acceptable standards — and therein lies the rub.

If the structure of the house – the walls, floors and roof – is in good shape and the renovation is largely related to room layout and finishings, then not only will it be cheaper than rebuilding but it will save 60 to 70 per cent of the materials and embodied CO². At the other end of the scale, four walls and a sagging roof are probably not worth saving. But between these two extremes is a point where a personal decision has to be taken. It would be nice to think that ecology would be the overriding factor, but the reality is that there will be many issues: merit, location, budget and planning restrictions will all have an impact. The trick is finding the right line and making the right decision.

Renovation is set to become just as important as new build — and it has to treated in the same way. There is no intrinsic reason why a renovation cannot be as ecologically sound, as energy efficient and sustainable as a new build, but we have to be pragmatic and recognise that there are times when it is better to demolish and rebuild — better for the owner and the environment.

"We gave our Victorian terrace and eco makeover"

(Pictured above and below)

“Despite the undoubted need for thousands of new homes in the UK, there is huge potential for updating the existing stock,” states Penney Poyzer who, with husband Gil Schalom, has carried out one of the greenest makeovers in Britain. A lengthy list of improvements to the Nottingham house includes huge tanks that store filtered rainwater; natural paints and earth plaster; a combustion boiler powered by waste timber; roof insulation made of recycled newspaper; hot-water solar panels; ozonefriendly insulated dry-lining; triple-glazed timber windows; and the pièce de résistance: a wormpowered sewage compost chamber in the cellar!

"We knocked down a bungalow to build green"

(Pictured below)

When Oliver Carpenter and Sue Braithwaite bought a tired 1930s bungalow on a dream plot in the Malverns, Worcestershire, they originally planned to renovate the structure, even though, as Oliver states, “It faced the wrong way and didn’t do justice to its surroundings.” It wasn’t until the structural engineer’s report declared the property unsound that they took the decision to knock down and start again. “Though we were planning a green build project, the first thing we did was demolish a house — not a good start!” laughs Oliver. “So we recycled everything we could.” The new house incorporates solar panels, a sedum roof, recycled newspaper insulation, a highefficiency woodburner, and was built almost entirely with locally sourced materials.

Easy ways to green up your old home

Insulate: Around 40 per cent of the heat that is lost from a home is through walls and the roof. This figure can be significantly reduced through the installation of simple loft insulation, which will cost between £130-200 and save around £150 a year in bills. Cavity wall insulation costs from around £135 to install and can save around £100 a year. Double glazing will reduce heat loss through windows.

Reduce Water Use: Homes use up to 1,000 litres of water a day. Consider installing a water meter and install low-flush WCs and simple showers, rather than power showers. A rain water harvesting system can reduce a household’s water consumption by as much as a half, providing water for toilets, the washing machine and gardening. They cost around £3-3,500 installed.

Generate Your Own Energy: Photovoltaic (PV) cells operate by turning solar radiation into electricity. The average home with a large south-facing roof could generate around half of its own electricity through this method. Prices vary but payback times are considered to be at least ten years. Wind turbines are another option and cost from around £1,300, but they are only effective in certain locations so a wind assessment should be carried out first.

Make Small Changes: Lighting accounts for some 15 per cent of an electricity bill, so switch to energy-saving bulbs which each save around £7 per year. A highefficiency condensing boiler will save around £180 a year, while simply adding a jacket and lagging to the hot water cylinder and pipes will cover its outlay in a year.

Green grants

Under the Low Carbon Buildings Programme, householders can apply for grants of up to £2,500 towards the cost of microgeneration technologies, including solar PV, wind turbines, heat pumps and biomass — if it is a certified product installed by a certified installer.

Local councils and energy suppliers such as British Gas will subsidise the cost of cavity wall insulation in existing homes.

Find out more about green grants at lowcarbonbuildings.org.uk or energysavingtrust.org.uk.

Further reading

• Feed-in Tariffs Explained
• Self-sufficiency: A Green Dream or Reality?
• How to Reduce Water Wastage