Operation retrofit: home energy efficiency

The average UK home wastes heat, energy and cash. But how can you improve your home’s energy efficiency and turn your pad green? asks Joe Clancy.

energy efficiency

Got £15,000 to spend on doing up your house? If so, which type of home improvement do you think likely to add most to the value of your property? a) a new kitchen; b) a new bathroom; or c) improving your home’s energy efficiency.

Those that answered ‘c’ can go to the top of the class. Evidence suggests that homes with a high energy efficiency rating will sell for 6% more than similar low-rated properties. That’s an extra £15,000 on a house valued at £250,000.

“There are people who’d think nothing of spending £15,000 on a new kitchen or bathroom, but would balk at spending that kind of money on insulating their property,” says John Doggart, chairman of the Sustainable Energy Academy, which promotes education on subjects such as home insulation and solar panels, as well as action to reduce the carbon footprint of buildings and communities.

“Yet they would be spending money on an improvement that would save hundreds of pounds a year on energy bills rather than on a depreciating asset, and on something that is going to last for 100 years.”


Domestic greenness

The academy is spearheading a programme to transform the UK’s existing housing stock, with the ultimate aim of reducing domestic carbon emissions by 60%. Called Old Home SuperHome, the scheme involves creating and promoting a network of refurbished, energy-efficient old buildings so that, in time, there will be examples of domestic greenness open to public viewing within 15 minutes of the majority of the population.

If the need to cut carbon emissions is not of itself a motivation to change for many people now, then basic economics increasingly will be. Not only is the cost of traditional sources of home energy soaring, but energy efficiency is predicted to become a significant influence on property prices as a consequence of the requirement that all houses up for sale or rent have an energy performance certificate. This was introduced in 2007 as part of the home information pack legislation.

The certificate provides a property with an official energy and carbon efficiency rating similar to the ratings given to fridges and washing machines. Homes are rated on an A to G scale with A being the most efficient. The average rating for a UK property now stands at D.

So, faced with this, what measures should come first? According to the academy, the most effective ways are to reduce the amount of cold air coming in and the amount of warm air escaping, thus reducing the amount of energy you are wasting. Beyond this, residents can further reduce the energy they use by being more energy efficient and then, finally, by substituting their conventional energy supply with renewables.


Energy efficiency premium

Given that the cost of conventional sources of energy is likely to continue rising, Doggart believes the rating on that certificate will increasingly affect property values. “In Australia, where EPCs have been around a lot longer, energy efficient properties are attracting a 6% premium,” he explains.

But the first thing we should be doing here in the UK, says Doggart, is to turn our homes into a “thermal cocoon” so heat doesn’t escape through the roof, floor, walls or windows. This is achieved by insulating not only the loft to high standards, but the floors and walls as well. The Energy Saving Trust says that around half of heat loss in a typical home is through the walls and loft, making them the two biggest areas where energy is wasted.

Adding 10ins of loft insulation could save around £205 a year on heating bills and around one tonne of CO2 per year. Cavity wall insulation is also a relatively cheap and easy home improvement for buildings with cavity walls, and the subsidies available from energy companies mean most properties can be suitably insulated for as little as £250.


Cocoon effect

Not every house, however, is of cavity wall construction. The UK has the oldest housing stock in the developed world and one in five UK homes were built before 1922, when solid wall construction was the norm. Such houses lose more heat than those built with cavity walls.

Insulating these older homes’ walls can be complex and expensive. To be most effective, the insulation needs to be 4ins thick and is best applied to external walls and then rendered over. But even those homeowners who have come to terms with the fact that their property’s attractive brickwork needs to be covered over could find that their local planning regulations may not allow this.

In such cases, the only answer is internal wall insulation which also needs to be 4ins thick. This is likely to require adjustments to door and window frames, skirting boards and ceiling mouldings, all adding to the cost. Even houses which have cavity walls but where the gap is less than four inches should have additional wall insulation to obtain the cocoon effect.


Floor insulation

Once the loft and walls are insulated, the next area to be tackled is the property’s ground-level flooring. The trend in recent years has been to replace fitted carpets with bare floorboards, but this has increased heat loss through gaps between floorboards and skirting.

These are simple to fix with a tube of silicon sealant available from most DIY stores and this will save around £25 a year on heating bills. Insulating beneath the floorboards can double the saving. Timber floors can be insulated by lifting the floorboards and laying mineral wool insulation supported by netting between the joists. The floorboards could then be turned over, sanded and polished.

The Energy Saving Trust estimates that around 400kg of CO2 a year can be saved by a combination of sealing the gaps and under-floor insulation in a semi-detached three-bedroom house. Installing argon-filled double-glazing is also crucial to the cocooning process as it cuts heat loss through windows by half. This is not cheap, but a start can be made by choosing the rooms that cost most to heat.

“The measures to cocoon your house are expensive but not out of the question,” Doggart adds. “Nearly 10% of householders find the money to change their bathroom every year. It should cost around £8,000 to fully insulate a three-bedroom semi. That is a lot of money, but it also costs a lot to do up your kitchen.

“The critical thing is that we need to spend this money in order to make our houses fit for purpose for the next 100 years and, in doing so, we will also help save the planet.”


Energy rating

He says householders who take these cocooning measures will normally see their energy rating improve to B – and, occasionally, to an A. To attain the A grade will often involve taking the step from energy saving to energy making.

The most effective way for householders to achieve this is by installing solar thermal panels which cost between £3,000 and £5,000, and which will provide around half of the household’s hot water needs. There is a multitude of solar panel manufacturers and products to choose from, but the utility companies, particularly the renewable-only companies such as Good Energy and Ecotricity, offer advice.

But Doggart advises caution, as some other additions such as wind turbines, ground source heat pumps and photovoltaic solar panels, may be too expensive for some domestic properties to justify the cost.

Broadcaster and journalist Penney Poyzer owns one of the most advanced eco-retrofit homes in Britain, a five-bedroom Victorian semi-detached in West Bridgford, Nottingham, for which she paid £84,000 11 years ago.


Lower energy bills

Penney estimates she would be paying energy bills of £2,500 a year to heat and provide hot water to the property had she not taken steps to improve its energy efficiency. Instead, her gas bill is just £15 a year. “We have one gas appliance: a gas cooker,” she says.

She has solar thermal panels on her roof and a biomass boiler fed by waste wood she collects for free, which provides additional hot water and all her heating needs. The property’s side and rear elevations have 6ins of external installation and, not wanting to change her home’s red brick appearance, the front wall has been internally insulated.

“It is not a job for a jobbing builder,” she says. “The work needs to be done by specialists to be most effective. Insulation has to come first. You need to reduce the amount of heat a house needs to the lowest point possible. Once it is fitted, nothing can go wrong with it.”


Make your house a low-carbon home: insulate

■ Make your home airtight: Fit draft proofing to doors and windows and fill the gaps between floorboards and skirting boards.

■ Insulate your loft to the recommended depth of 270mm (10ins): Most energy companies provide grants and it can be a straightforward job for an installer or competent DIYer.

■ Insulate external walls: Around a third of all the heat lost in an un-insulated home is through the walls. If your home was built from 1920 onwards, its external walls are likely to be made of two layers with a small gap or cavity between them. Insulating cavity walls reduces heat loss and could save you around £160 a year on your fuel bills. Solid walls lose more heat than cavity walls and the only way to redress this is to insulate them on the inside or outside. External wall insulation is more expensive than cavity wall insulation but it could cut your energy bills by around £500 a year, so it could pay for itself in around 11 years. Again, grants are available from energy companies.

■ Insulate under ground-level floorboards with mineral wool insulation, supported by netting, laid between the joists. This will save around £50 a year on an average three bedroom semi-detached house.

Make your house a low-carbon home: instal

■ Install double glazing, which can halve heat loss through windows. Look for the Energy Saving Recommended label. The whole window (frame and glass) is assessed on a rating of A to G by the British Fenestration Ratings Council. If you’re on a budget, fitting secondary glazing could be the answer.

■ Install an efficient heating system. Replacing an old, inefficient boiler with a condensing boiler and a full set of heating controls could cut your bills by £300 a year. Boilers account for around 60% of the CO2 emissions in a gas-heated home. A biomass boiler could save around £470 a year on heating bills. Biomass is made up of plants and untreated wood or wood waste. Although burning wood releases CO2, it is the same amount as was absorbed while the wood was growing. If a new tree is planted for each one burned, there are no overall carbon emissions. I can also provide a good use for disposing of waste wood that might otherwise be sent to a landfill site.

■ Install solar thermal panels. Solar water heating uses heat from the sun to work alongside your conventional water heater. It works via solar collectors on the roof, which soak up the sun’s energy, then transfer it to the hot water cylinder – warming it up throughout the day. Solar water heating in the average home with south facing roofs could take care of around a third of your hot water needs, and save around £40 a year in energy bills – cutting your CO2 emissions by up to 350kg a year.

Take these seven steps and you could be in heaven when the rating on your home’s Energy Performance Certificate soars. The average rating is now D, but these measures should see it earn at least a B if not an A.

• Originally published in GreenerLiving magazine in August 2009



Peter a journalist with 30 years experience of freelance writing, UK national newspaper and magazine production roles, and business development. In 2007, he developed and launched a mainstream-style green consumer magazine in the UK, called GreenerLiving, as a means of promoting sustainable change ‘within the system’. GreenerLiving closed during the post-crash recession, but Peter went on to become managing editor of the international ethical business title, Ethical Performance. However, Peter felt that the CSR sector has not succeeded in changing corporate priorities anywhere near fast enough, and so I decided to leave the treadmill of corporate employment and debt accumulation to focus on my own projects. Now poorer but a billion million times happier, he writes on political, economic and social issues – usually seriously, but sometimes as satire. He's currently writing Psychopath Economics, a book about the logic of social and economic power, belief systems, and the rise and fall of societies. Peter is convinced that ordinary people must educate themselves and exercise their economic leverage if we are to avoid social and environmental destruction.

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