How can i make my home greener?
Energy effeciency expert Nigel Humphrey on keeping your home comfortable while also cutting bills
It seems simple, doesn’t it? Use less energy, produce less CO2, and wear thicker sweaters. But being cold isn’t much fun and, after the winter we’ve just experienced, neither is seeing our energy bills mount up. So what can you do to make your house cheaper to run, more comfortable and eco friendly, and how much will it cost?
Whether your house is new or old, the rules are the same:
Keep the heat in and the cold out. The best energy is free and zero CO2.. Use as little imported energy as possible, and don’t waste it.
The trick is working out exactly how to do all of that. There’s so many decisions to make; which insulation and how much? What sort of boiler? Radiators or underfloor heating, and what controls? What do you do first, and what will be most cost effective?
Useful to know
First, according to Government statistics on energy usage in the UK, on average about 63 per cent of your bills go to space heating, 11 per cent to water heating, 24 per cent to lighting and appliances, and three per cent to cooking. The average UK household is about 85m2 and spends about £600 on gas, (mostly space and
water heating) and £400 on electricity, (lights and appliances), which equates to about 268Kwh/m2/year. Generally speaking, the electricity delivered to your home produces a lot more CO2 than the gas does.
Second, our perception of comfort is affected by the rate at which the air temperature around us changes. If there’s a cold draught, the temperature change will be rapid and you will feel chilly. A room at 21°C with cold draughts will feel colder and less comfortable than a room at 19°C with no draughts.
Third, the average UK dwelling has between five to 10 air changes per hour, meaning that the air in your house has to be heated to a comfortable temperature five to 10 times an hour. A very energy-efficient house might have less than two air changes per hour.
You can save about £30 a year just by turning appliances off standby. Reduce hot water usage by taking a shower instead of a bath and by fitting a waterefficient showerhead – saving up to £75 a year for a family of four, as well as £120 if your water usage is metered. Switching to LEDS might cost £100 in the average home but will save £35 a year. Turning off the lights when they’re not being used saves £14 a year. And when your fridge, freezer or washing machine stop working, replacing them with energy-efficient A++ rated appliances will give more savings.
Heating spaces accounts for more than half the average energy consumption, but it can be significantly reduced by insulating the building fabric (floors, walls, ceilings, roof spaces). Issues to consider are, where to insulate, (internally, cavity, or externally on walls), what insulation to use and how much, and to be aware of creating a potential for condensation and damp. To avoid this, wipe away condensation when you see it, make sure rooms are properly ventilated, use a dehumidifier, or fans in the kitchen and bathroom, and ensure there are no areas where damp can penetrate, either through structural defects, leaky pipes or lack of a working damp-proof course.
There are many different types of insulation, they vary a lot in cost and in their own environmental impact. As with many materials, the less processed
‘Our perception of comfort is affected by the rate at which air temperature changes. A room at 21˚C with draughts will feel colder than one at 19˚C with no draughts’
it is and the nearer to its natural state, the less the amount of energy that’s used to produce it (embodied energy) and the less polluting it’s likely to be.
The loft is probably the easiest insulation job and is one that you can do yourself. It could save as much as £225 a year. Floor insulation could save £75 a year, cavity and solid wall insulation between £75 to £250 a year. This is work best done by professionals, so they’ll cost more, but there may be grants available. Good places to check whether there are any are Which.co.uk, Nestwales.org.uk if you live in Wales, and the Energy Grants Calculator at gov.uk/energy-grants-calculator
Cutting down the draughts, and the number of air changes per hour (infiltration), can also greatly reduce the heating load. How much is saved will depend on how effectively this is done, but halving the infiltration rate can halve the energy load. If there are fewer draughts it also becomes possible to reduce the set temperatures, and every degree of reduction will save about £30 a year.
In older buildings draughts are everywhere – round the windows ➤
‘Renewable heat systems are desirable if you want to be green, but only really become cost-effective once you’ve got the building working efficiently’
and doors, through the cavity walls, through air bricks, around sockets and light switches, through beam ends, down the chimney and between floorboards. This is partly because traditional UK building practice relied on high levels of ventilation to dry out the water it was assumed would get into your house. It’s possible to get draught exclusion done professionally for between £75-£250. The Energy Saving Trust has a lot of helpful advice on DIY draught-proofing.
Heating the home
Once the warm air in the building is prevented from getting out and cold air from getting in, the final steps are to choose the most efficient energy source, distribution system and controls.
A conventional gas condensing boiler will cost about £2,500 installed (including additional thermostatic radiator valves), and the EST website quotes saving of up to £320 a year if the boiler replaced was band G and only 70 per cent efficient.
renewable heat systems are desirable if you want to be green, but only really become cost-effective once you’ve got the building working efficiently. Fuels range from biomass to the various forms of renewable electricity (generated on site through things like solar panels, wind turbines, or running water, for those near streams or rivers, or imported).
Heat sources start with wood boilers and stoves, using logs, wood chips, or pellets. They’re quite conventional in the way they work, and more feasible if you have the space and the time to run them. An automatically fed pellet boiler for an average home costs between £9,000 and £21,000.
heat pumps might cost between £7,000 and £11,000. they work like a fridge in reverse, taking heat from the air or the ground and pumping it into your house, using maybe 1Kw of electricity to provide 4Kw of heat. they’re more automatic in the way they work, and since they don’t need storage space for the fuel, are better suited to urban locations. Most will sound about the same as a fridge running, but issues of noise needs to be considered in urban locations.
Thermal stores – typically a big water tank – can use a single renewable energy source or several. Systems can combine a gas or oil boiler with solar thermal, PV, wood-fired range cooker, wind, and a ground source heat pump. Costs will vary according to the technologies being used.
A heating system isn’t something that you generally install yourself, particularly if gas or electricity are involved, and the building regulations require that the work be done by a competent person. To find registered installers try the Competent Persons Register. Be sure the installers are MCS Certified, and if using gas or oil, are registered with GAS SAFE or OFTEC.
The right heating system for you and your house depends on the size and construction of the property, how you live in it and your budget.
Generally, a thermally massive building, such as a converted barn or Georgian stone house, that’s in use throughout the day, is best served by a system that’s on all the time. A good option will be a heat pump powered by renewable electricity distributing to underfloor heating and with smart optimised controls. At the opposite end of the spectrum, a thermally lightweight building will heat up and cool down quickly. If the use is very intermittent, a wood-burning stove, heating up the air only might be best.
the website energysavingtrust.org.uk offers further information on boiler replacement, renewable energy, home insulation, and energy efficiency. see examples of energy-efficient homes and find details of open house events at superhomes.org.uk.