Building Backwards

Look at pretty much any new housing development and it probably looks like this; traditional, familiar materials and forms - bricks, tiles, small windows, maintenance-free pvc pretending to be wooden window frames and iron gutters. Look around the show house and you're likely to see heating radiators below the window cills and a gas boiler in the utility room. The houses will be a selection of a few standard plans, probably given variety by varying brick colour or extra cladding materials. It matter not a jot which way they face and the chances are that behind the brick is a timber frame.

Because the houses have to comply with building regulations controlling energy conservation the houses will be very well insulated and airtight, but those small windows, designed to minimise heat losses, are of little use when it comes to grabbing the free heat available from winter sunshine, while the airtightness is a nonsense when every kitchen, bathroom and utility room has to have an extract fan to avoid condensation by throwing out the expensively gas-heated air.

Britain needs hundreds of thousands of new homes and needs to reduce its carbon footprint. Heating homes is one of the biggest users of energy. It is madness to be heating brand new homes by burning fossil fuels, but the house-builders need to compete: to provide houses that will sell and build them cheaper than their competitors. They have to comply with planning policies and building regulations but they do so at the minimum possible cost and they go no further than they have to towards low carbon, energy-efficient homes. We are building thousands upon thousands of backward-looking, out-of-date houses and adding to the existing housing stock of inefficient homes which are difficult and expensive to retro-fit and upgrade.

Carrot and stick

There are plans to make all new homes carbon neutral in due course, but the knowledge, techniques, materials and technology are all there to do it now. Meanwhile we just keep churning out yesterday's homes.

Look at one-off architect-designed houses and the best of social housing and you will see what could easily be rolled out to everyone. There is a raft of measures that can make homes radically more energy efficient. Building regulations recognise them and they can be factored into the required energy calculations (allowing larger windows, for example, if the solar gain offsets any reduction in insulation) but these measures are not mandatory, and until they are they will be the exception rather than the rule.

There would be no difficulty in improving planning policies, building regulations or both to make it difficult to avoid building efficient low-carbon homes. As we see everywhere, widespread adoption of technology causes costs to tumble, and the minimal additional initial costs would apply to every house-builder so avoiding the current 'race to the bottom'. It would be easy to make low-carbon design ubiquitous in new homes by a carrot-and-stick approach: encourage using subsidies and grants and by making planning permission easier for green approaches, while stepping up regulation to make it difficult to avoid using them.

High levels of insulation are a given in modern building, thanks to building regulations, though even better performance is a good thing, but the most useful additional energy-saving approaches are outlined below. There are others - wind energy and rainwater harvesting for example - but these are probably not so well-established or effective. Some improvements are possible to existing houses - photovoltaic solar panels in particular are a common sight, fixed over roof tiles - but some are difficult to retro-fit and all are better incorporated into the original build. Retro-fitting may be the best approach for the existing housing stock but every new home built should be designed to incorporate some or all of the following measures.

Passive heating

Windows inevitably lose more heat than the walls they're in, even the most efficient triple-glazed argon-filled windows. But windows let the sunshine in and warm houses up. In the winter too much glass can drain heat away but in the summer it can cause overheating. Thoughtful design can turn these problems into positives but building regulations and lack of imagination means houses now have smaller windows and darker rooms than those built back in the 1960s. In summer the sun rises in the north-east and is very high in the southern sky at midday before setting in the north-west. In winter, though, it rises in the south-east, remains low in the south at midday and sets in the south-west. Large windows on the south side of a house soak up the winter sun when its heat is welcome, but need shade from roof overhangs to avoid overheating when the summer sun is high in the sky. Landscaping can help - deciduous trees will shade south-facing windows in summer but lose their leaves in winter to let the sunshine in. East and west- facing windows need care to avoid excess heat in summer mornings and evenings, while windows on the north side will always waste heat in winter. This is not rocket science. It is not difficult to design homes to be light with generous expanses of glass (saving on artificial lighting) without pouring out heat in cold weather, but orientation is critical and this is something that is ignored in 95% of new housing.

Solar panels

Almost all our energy (geothermal energy being the exception) comes from the sun and the most direct way to harness it is using solar panels. Thermal solar panels which heat hot water for our bathrooms and kitchens have been around for years but are now outnumbered by photovoltaic panels which generate electricity. Subsidies including the feed-in-tariff and renewable heat incentive have helped drive installation and numbers have brought down costs so the subsidies can be phased out as improving efficiencies and falling capital costs make solar panels viable without financial incentives. This is all free energy and should be included as standard in every new home built. Of course, the most sunshine tends to occur when we least need the energy to heat and light our homes, but what we don't need is fed back into the grid and lessens the amount of fossil fuels needed by power stations. As we switch from petrol/diesel to electric cars these can be charged for free, while the same battery technology is available for domestic use, so the power generated when the sun shines is available after dark, and is being installed in vast energy banks (often using disused power stations) to do the same on a bigger scale and over longer timeframes.

Heat-recovery ventilation

Building regulations mean that new homes are much better insulated than before, so less heat is lost through walls, windows and roofs. Consequently, the bulk of heat loss is what is known as ventilation loss - simply throwing out warm air. The absurdity of extract fans in airtight buildings has already been mentioned, but ventilation is essential to keep air fresh and avoid problems like mould. The answer MVHR or mechanical ventilation with heat recovery. It's a mouthful but is actually very simple. MVHR is widely used and is cheap and well-proven technology but is not widely understood and is ignored by house-builders. In a typical system a box housing a couple of fans and filters sits in the roof space with air ducts leading to discreet outlets in ceilings or walls. Warm, moist, stale air from kitchens and bathrooms is extracted and fresh air from outside is gently fed into living rooms and bedrooms. But the trick is to pass the warm, stale extracted air through a heat exchanger where most of the heat is transferred to the fresh, filtered air being brought in. Typically, the fresh air coming in will only be a degree or so cooler than the heated air being expelled. Almost all of the energy remains in the home. Extract fans are not needed and the air is kept fresh without having to open windows in cold weather.

Heat pumps

Traditional heating by burning coal, gas or oil is easy to understand but wasteful. At worst, most of the heat goes up the chimney but even the most efficient systems produce much less useful energy than is consumed. Heat pumps, though, can produce two or three times as much useful energy as they use. Rather than producing heat directly they use a compressor to transfer heat from outside the home to inside. An air-source heat pump, for example, cools a lot of the outside air by a few degrees and uses the heat gained to give a much bigger temperature rise in the primary circuit of a heating system. Heat pumps work best with the lower temperatures needed for underfloor heating, removing the clutter of wall-mounted radiators. They use clean electricity (increasingly from sustainable sources) and, since the principles involved are similar to a fridge, may also be able to cooling as climate change brings higher summer temperatures. Like teh other technologies, heat pumps are well-proven, widely used and getting cheaper, but you won't find them in a typical new home.

Money talks

There are financial incentives to encourage homeowners to be greener. The Renewable Heat Incentive gives quarterly payments over seven years for heat pumps, thermal (hot water) solar panels and bio-mass boilers; grants support upgrading thermal insulation and replacing old, inefficient boilers, and long-term incentives to encourage the use of photovoltaics have been so successful in building take-up and lowering costs that they have were steadily reduced then discontinued. These are piecemeal incentives equivalent to encouraging the purchase of electric vehicles by offering cashback - already being scaled back and no doubt due to discontinue as EV prices fall and fossil fuel prices rise. But the main drivers (no pun intended) for reducing pollution from vehicles are taxes on fossil fuels and road tax discounts for cleaner vehicles (or penalties for dirty ones, if you prefer). Taxation can be easily used to drive down pollution from vehicles, but taxation is not being used to clean up housing.

New houses are being built without energy-saving features because they would increase the purchase cost and impact sales, and even if all new houses were more energy-efficient, the vast bulk of housing is old and most of it is anything but energy-efficient. The way to focus people's attention on the need for energy-efficient homes is by a direct attack on their wallets.

A new report by the government's Science and Technology Select Committee suggests increasing stamp duty for badly-insulated homes. This is a novel idea but is a very low-key one too. If stamp duty - basically a purchase tax for houses - took into account not just the value of the property but its energy efficiency, well-insulated homes with features like solar panels and MVHR would gain a price advantage. Owners would be more likely to go green so their house was more saleable and old, unimproved, energy-wasting houses would be hard to shift.

This measure would do a great deal to green the country's housing stock, but would only apply when a house was sold. Taking it further the costs of owning (rather than buying) a home could be addressed by taxation. Green energy (solar and wind for example) are subsidised to encourage adoption, but as the subsidies are scaled down generators should be increasingly taxed for using fossil fuels. Homeowners' running costs extend beyond the price of fuel: council taxes are big bills but are just based on building value and on local authority budgets. An element of property tax could be based on the home's energy efficiency (just like road tax for cars) so big, old, draughty, badly-insulated houses became costlier to keep while a zero-net-energy eco-house paid nothing, just like an electric car pays no road tax.