Save energy

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Energy is ever more expensive, and its use has become a hot topic politically. Here are various ways DIYers can save energy.


Draughtproofing is an easy minimum cost way to save energy in old houses. Self adhesive foam strip, profiled rubber strip and brush strip are all effective. Low cost self adhesive foams tend to have short life, but still save money. Draughtproof all 4 edges of doors & windows, and don't forget the letterbox.

The gaps in suspended timber ground floors in old properties often produce draughts. See further down for solutions.


Cavity wall insulation

Make sure you've got it, if you have cavity walls of a suitable type (rattrap bond and rubble walls should not be cavity filled.) Grants are widely available. The increased cost to heat a house for several years without insulation is greater than the cost of the insulation.

Loft insulation

Lots of it. Loft insulation is an especially effective way to achieve payback.

Where goods are stored in the loft, boxed items trap air and thus have a little insulating value.

Solid wall insulation

Non-cavity walls can have insulation applied to the inner or outer surface. The cost and work involved are of course greater than cavity fill.

There are 3 ways to fit interior insulation.

  1. Timber battens, insulation between, plasterboard, skim with plaster
  2. Solid sheet insulation, plasterboard, skim
  3. Solid sheet insulation with a hard cement front surface, skim

Its possible to just add a cavity, which provides significant insulation, using battens and plasterboard only. But the cost versus benefit of insulation means it should be included if at all possible. Its much better though to use rigid insulation sheet battenless, it produces more insulation value.

Exterior insulation usually consists of solid sheet insulation, with EML screwed in place over it, then rendered with cement mortar. Insulating render is an alternative option with lower insulation levels.

For the financially troubled, its possible to insulate walls for £2 where appearance doesn't matter. Scrap paper products are brushed with borax solution and fixed with wallpaper adhesive.

  • Cardboard can be applied in layers to the required depth.
  • or a single layer of narrow card boxes, 1"-2" deep, creates an insulating cavity
  • filling shallow boxes with scrap insulation helps further
  • Its possible to fit foil backed plasterboard over it later.
  • Paper products are not suitable where there's risk of damp

Underfloor insulation

Some people retrofit insulation under suspended timber floors and concrete floors. Both usually involve taking the whole floor up, so are only occasionally practical. The saving can be significant over time, if the floor had to come up anyway. If not, there's a lot of input to pay back. Occasionally there's a crawl space to enable fitting without disturbing the floor.

Less effective but still useful methods for draught prone ground floor floorboards are

  • Laminate or hardwood flooring laid over the floor to block draughts
  • carpet & underlay draughtproofs and insulates a little.
  • filling floorboard gaps is partially effective, some of the filler tends to fall out with movement


Double glazing

Retrofitting double glazing usually fails to pay its costs back. Also it incurs the additional cost and energy use of replacing failed sealed glazing units.

However when windows must be replaced for other reasons, choosing double glazing usually makes sense.

Secondary glazing

  • can pay back
  • can cause condensation & rot of timber windows
  • can be applied as opening sheets or non-opening.
  • is easily made removable


  • Acrylic secondary glazing eventually deteriorates, but can last decades.
  • Secondary glazing starts at about £6 a window using a plastic film glazing kit. This lasts a couple of years if not abused, but its weak and easily damaged. Holes can be patched, and if necessary the panel can be retautened with a hair dryer.
  • Polythene sheet costs less than £1 a window, but isn't fully clear and doesn't shrink flat with a hairdryer. Only suited to out of the way windows.

Sash windows

Sliding sash windows can be draughty. A few types of draughtproofing can be fitted.

A favoured method is to remove the sliding sash, route a groove around its perimeter and insert a thin brush strip. This works well and stops rattles too, though it does make the window slide less freely. One alternative product used in the same way is a simple flexible plastic strip.

The cheapest method is to apply sellotape all along the gap where sash meets frame. Don't forget the gap where the sashes meet.

Leaded lights

Lead is an excellant thermal conductor, leaded windows have lots of it, and the design of these windows often leads to them leaking air as well. Secondary glazing dramatically improves performance.


Heavy curtains help reduce heat loss at night by slowing air circulation past the window. The benefit is not comparable with double or secondary glazing.

Insulating curtain lining further reduces heat loss. 4mm & 6mm are available from haberdashers or online.

Closing off gaps around curtains helps further.

  • Pelmets at the top.
  • Minimal gap between curtain bottom and cill
  • Left and right curtain edges can be velcroed to the frame or wall


Roller blinds give the same air slowing effect as curtains. Minimising the gap between blind and window maximises this effect.

Slatted blinds let a lot more air through, and don't insulate significantly.

Steel windows

Steel frames conduct heat out of the building. Secondary glazing is beneficial.

If a steel window doesn't close properly, excess paint build up is often the cause. Crittall steel windows were only designed to tolerate upto 3 layers of paint, and most are now old enough to have a good deal more on them.

Damaged windows that don't align properly can be draughtproofed by applying silicone, placing polythene sheet over the silicone to prevent it sticking to the opening sash, and closing the window. The sealant is thus moulded in situ to block any gaps.

Rust holes in steel windows can be repaired with the same methods used for cars.


Room stat

There are some heating systems around with no room thermostat! if you can't find a room stat, you need one. TRVs are only partially thermostatic, and can't replace the function of the room stat.


Some old boilers used cast iron heat exchangers. These are inefficient and its worth working out if such boilers are better replaced. Often they're not.

Old boilers with the more common pressed metal exchangers are usually not worth replacing on financial grounds. Modern boilers tend to have much shorter lives and higher repair costs, offsetting quite a lot of fuel saving.

Boiler efficiency and maximum heating system output both depend on the temperature of the primary circuit, which is usually controlled by a thermostat on the boiler. Reducing this temperature reduces max system heat output, but improves efficiency to some extent. The gain is greater with condensing boilers. The thermostat on the boiler can be turned down in milder weather, and up again in cold times. Weather compensation does this automatically, but is usually only found on more sophisticated domestic heating installations.

Programmable room stat

These save money if you use them to heat the house to a lower temp for part of the day. If you don't, they don't save a thing. Being electronic they have shorter mean life than bimetal stats.


TRVs improve the room by room thermal control, shaving costs. Despite the name they are only partially thermostatic, and offer improvement rather than complete control. Heating systems should have a TRV on all radiators except one. Some TRVs last well, some don't.

Turn radiators off

Turn off radiators in spare rooms etc. Such rooms still get partial heating from elsewhere in the house. Keep an eye out for damp, in a minority of cases this can result.

Room programmers & thermostats

Controlling the timing of heating or the temperature individually for each room trims waste further. However its not trivial to fit such control systems, and not many DIYers do so.

Electric heating

This costs much more than mains gas or oil to run.

Storage heating on a reduced night time tariff costs much less than plug-in heaters.

With electric heating only, there is a big saving to be had by only heating 1 or 2 rooms. With gas central heating on the other hand, heating 1 or 2 rooms electrically may save nothing due to the roughly triple cost of electric heat.


Wearing clothes saves energy. Wearing more clothes saves more energy. Painfully obvious, but sometimes overlooked.


Replacing filament bulbs with CFL saves money - not everyone likes them though. The claimed power equivalents on the packet are misleading comparisons with softone lamps, not the popular GLS Filament Lamps. 4x is a more realistic rule of thumb, with 3x for reflector types, and down to 2x for very compact reflector types where the majority of the reflector is blocked by the tube.

Where appearance doesn't matter, eg for garages, linear fluorescent is the most energy efficient of all domestic lighting types. The longer the tube, the more efficient. Tube efficacies vary over about a 2:1 range, check before buying. Linear fluorescent lighting is often done badly, see Fluorescent for recommendations.

Halogen downlighting is a particularly energy hungry type of domestic lighting. Energy use can be cut by a factor of 10x by changing to CFL lights, and not using them as downlighting.

The appearance of halogen can be retained to a fair extent by using 5w or 10w halogen spotlights and adding concealed CFL or linear fluorescent lighting.

A lot of 500w halogen outdoor lighting can have the bulbs replaced with 150w ones.

Dimming PIR fittings waste thousands of pounds in energy.

A switchbank can much reduce lighting cost in many cases.

Dimmers only work with Filament Lamps, and produce little saving compared to full brightness, and waste energy compared to switching less total bulb power on.



Packing the machine full before use reduces frequency of run and total energy use. A full machine costs half as much per item to run, and the machine lasts much longer.

Lower temp wash programs save energy.

Replacing an old machine with a more efficient one is unlikely to be worthwhile.

Washing machine

40C washes use less energy than hotter programs, but machines do need at least an occasional hot wash to clean the machine. Pongs result otherwise.

Washing below 40 isn't recommended, muck builds up and pong eventually takes over. Buying a new machine because you used cool washes is not energy efficiency.

An occasional boil wash with citric acid helps keep the machine clean, prolonging its useful life. For maximum effectiveness, when the water in the tub has reached close to boiling, switch machine off and leave overnight. Complete the wash program in the morning.

Users of economy 7 type schemes may find the washing machine too noisy to run at night on half price leccy. This is often solvable by fitting noise reduction to the machine. Rubber mat or cardboard is glued on to the case interior all round, and onto the drum exterior where it won't foul anything when the drum moves.

Most top loading machines use many times the amount of energy per wash, at many times the run cost. If you need the higher throughput, a pair of front loaders stacked has several advantages over a top loader.

Tumble drier

Most of the energy use of tumble driers can be avoided with this clothes dryer

Drying clothes on a line outdoors costs nothing in summer.

Tumble driers vary a lot in energy use.



Put foods to be cooked in without preheating the oven. The food's ready a couple of minutes sooner, and you lose 5 minutes of on-time. This works with almost all foods, with fast cooking items it alters the cooking times a little.


Use lids on pans, turning the gas down very low. Once water is at boiling point, its impossible to make foods cook any faster. Many people use over 10x as much gas as needed to cook food. All the food must be covered by water or some won't cook so quickly. On high setting, a lot of the flame's heat passes right past the pan. On a low setting, heat transfer is much more efficient.

Glass plates can be used on pans instead of lids. Glass pans make it easier to see that the food is still boiling, but not too vigorously, and glass pans behave very well with low power cooking.

Sometimes 2 foods can be cooked in the one pan together.

Pressure cookers cook many foods faster than boiling.


Microwaving instead of boiling, giving less loss of flavour & nutrients, quicker cooking and much less energy use.

A microwave & convection combi cooker can cook with both methods at once. This can produce oven like results with a fraction of the cooking time and energy use.

2 things microwaves are less energy efficient at are boiling water and cooking rice.

Extractor fan

Kitchen extractor fans can throw a fair bit of heat away. They reduce the sticky grease that's caused by boiling food on the hob, so there's no point using them in winter when only the oven's on. Use the minimum fan speed required to remove most of the steam.

Using low hob power with lids eliminates most of the kitchen grease formation, and steam too.


Old non-jug kettles waste energy by often boiling more water than is needed.

Boiling the exact amount of water needed reduces energy use. This is hard to judge but easy to measure. A kettle uses around half as much energy as a microwave if the exact amount of water is boiled.

Low energy cooking

A few methods can be used by people really determined to save energy.

There are many hot dishes that require little or no cooking. The art of creating good quality dishes very quickly is called short order cooking.

Some meals only need some of the ingredients cooking, and the others (eg tinned ingredients) can be added after the cooking. Some recipes work fine if you skip the cooking entirely.

Haybox cookery produces slow cooked meals using only enough power to heat them up. The food is brought to boiling, then put in an insulated box (originally it was buried in hay). This keeps it hot, like a slow cooker.

Thermos cooking is a more modern version of the haybox. Soups can be put in a thermos boiling hot but uncooked, and be ready by lunch time. The small capacity of these vacuum flasks is a major limitation.

Slow cookers can save energy if they're insulated.

Steamers avoid heating up a large amount of water.

Pan frying on a low flame is quite efficient due to short cooking times.

Cooking lots of servings at once and freezing uses less energy per meal. Defrosting them in the fridge reduces energy use marginally.

If you're even more determined to cut energy use, pans can be stacked, with the top pan used to slowly heat an item through while the bottom one cooks.

Fridge & freezer

Old freezers from the 1970s consume enough extra power to cost more than a new freezer, even if they were free.

Occasionally people have stuck polystyrene foam insulation over the outside of their freezer to cut energy consumption even further. This does work, and is sometimes considered by people running a small offgrid power system.

A fridge that uses no energy at all.

On some fridges & freezers a non-obvious fault makes the compressor run continuously. This increases electricity consumption to in the region of £70 a year, or upto £200 a year for freezers decades old. At £500-£2000 per decade its cheaper to buy a new one than to use the old one. This problem is caused by partial loss of coolant, or less often by saturated insulation.

Electricity meter

A power monitoring meter makes people aware of what is using how much, and this usually results in painless energy reductions. There are 2 types of meter. One indicates total house power consumption. The other monitors the power use over time of one appliance or one lead. Savings usually pay for the meter cost.


A desktop PC may use 70w and its monitor 30-70w, versus a laptop's 20w (approx & variable figures). If a machine's in use 24/7, the difference between the 2 is around £50 per year. Whether its worth moving over to a laptop depends on the laptop cost and hours of use, but usually its not, for cost saving alone.

Most desktop computer power supplies have an efficiency percentage in the 70s due to cost cutting. More efficient power supplies in the 80s & 90s percent are available for desktop machines.

Grahics cards with their own cooling fan use more power.

Setting machines to power down discs or shut down after a while is well known. Changing the times to suit you can save more.

TV & Monitor

LCD monitors often use less power than CRTs, but this isn't always so. Its not enough saving to offset the cost of replacing them however, or the embodied energy.

Plasma TVs are much more power hungry than LCD.

Standby power

Much political mileage has been made of appliances consuming power while on standby. All consume some, but the quantity and cost of this power is in most cases tiny. There are occasional exceptions, primarily some set top boxes, and if found such items can be switched fully off when not in use.

Hot water

Ensure your cylinder has either a foam coating or a fitted jacket. With jackets, check for gaps.

Fix dripping or dribbling hot taps.

Hot water cylinders are usually fitted in restricted spaces, creating a space around the cylinder where more insulation can be added at no cost. Loft insulation, packaging peanuts, bubble wrap, jiffy bags, polystyrene foam, and even screwed up paper all trap air and provide insulation. Don't bury the flex to an immersion heater in insulation.

See also Category:Domestic Hot Water



  • Use a lower water flow.
  • Turn off booster pumps.
  • Use an aerator
  • Use a low flow shower head
  • If necessary, turn water off while soaping.
  • link to [how to stop teenagers taking forever in the shower]
  • Drain Heat Exchanger
  • Experimental recirculating shower


4-6" of water was standard war time practice, and does the job.


Batteries are highly inefficient ways to store energy.

Using rechargeable batteries gives a good saving on a lot of battery appliances. A £10 set of 4 NiMH batteries with charger can achieve 500-1000 charge cycles, replacing up to 1000 batteries. That's a cost equivalent to 1p per dry battery.

Rechargeables aren't well suited to all tasks, as they tend to self discharge when sitting unused.

Running battery items from a wallwart wipes out almost all the run cost of batteries.


Most wallwarts are reasonably efficient, but not all. If one gets hot, its not. Sometimes its easy to replace a bad one with another of same voltage output, at least as much current output, regulated or not as per the original, and with the same connector and polarity.


Low energy models aren't available, but they can sometimes be trained to switch things off by being promised a fixed amount of money minus the week's gas & electricity costs. Its not hard to work out using the bills and meter readings.


Finally, check you're getting a good deal on power.

See Also

Are you being charged triple for your gas?