For energy saving advice and support
in the Bristol and Somerset area:
0800 082 2234


Cavity Wall Insulation

How can I tell if I have cavity walls?

There are three simple things you can check. Firstly, the age of your house. If it was constructed before 1932 it is unlikely to have cavity walls. If it dates from 1932-1982 it probably does, and after 1982 almost certainly. Secondly, check the pattern of the brickwork. If you see only the long side of the brick ('stretcher bond' in brickie parlance) the property is likely to have cavity walls. If you see a long-short-long-short pattern, this suggests a solid wall with no cavity. Finally, measure the thickness of your wall. If it is more than 30cm (11.5 inches) and constructed of brick it is likely to have a cavity, although some stone walls can be considerably thicker than this.

Can all cavity walls be insulated?

Most cavity walls can be insulated, but there are a few exceptions including those where the masonry or brick work of the property is in poor condition, the wall-ties are dirty, the cavity is less than 50mm wide or if the walls are exposed to persistent driving rain (e.g. coastal properties)

What materials are used for cavity wall insulation?

CWI comes in three main types. Expanding foam, mineral fibre and the increasingly widely used poly-bead or carbon bead which tend to be the most energy efficient.

Will cavity wall insulation cause damp?

Properties with structural problems, wall cavities full of rubble, dirty wall ties and a persistent exposure to driving wind and rain (e.g. coastal properties) may not be suitable for cavity wall insulation. Before having cavity wall insulation installed a free survey can be carried out to ensure that the walls are suitable. By making the surface of the walls less cold and helping to maintain air temperature in the home cavity wall insulation can help reduce damp caused by condensation.

How do I find a reputable installer?

Look out for installers that are registered with the National Insulation Association and can offer the Cavity Insulation Guarantee Agency (CIGA) guarantee. 

How long does it take to insulate the walls?

For a typical 3 bedroom property it usually takes 2-3 hours to install cavity wall insulation.

Do the installers need to come into my house?

Yes, the installers must carry out checks before and after the installation, including checking heating appliances, so they will need access to the property.

Does cavity wall insulation deteriorate over time?

Modern cavity wall insulation is estimated to have a lifetime of around 40 years and should come with a 25-year independent guarantee from the Cavity Insulation Guarantee Agency.

What if I have problems after the insulation is installed?

If there are any problems with the insulation work first try to resolve it with the installer. If the matter is not resolved contact the Cavity Insulation Guarantee Agency.

My walls don't have a cavity, can I still insulate them?

Yes, you can insulate solid walls externally with an insulating render or cladding. Alternatively you can use a form of internal wall insulation and insulate from the inside.

Solid wall insulation

Aren't all walls, 'solid walls'?

The term 'solid wall' refers to walls constructed as a single solid layer with no cavity section within the wall. This means the wall is literally solid from inside to outside. Solid walls are typically made from brick or stone, and are generally found within houses built before the 1930s.

How can I insulate solid walls?

Insulation for solid walled properties can be carried out on the inside (internal wall insulation) or the outside (external wall insulation) of the property. To fit internal wall insulation any fixtures and fittings must be removed and refitted afterwards. This includes switches, sockets, skirting boards, kitchen units, etc. To fit external wall insulation you may require scaffolding and fixtures such as drain pipes and satellite dishes may need to be removed and refitted afterwards.

What is 'thermal mass' and why is it relevant when considering solid wall insulation?

Solid brick or stone walls will absorb heat from both inside and outside of the property during the day, acting as a heat sink. Their relative ability to do this is known as their 'thermal mass'. Some of the heat absorbed by the walls is released back into the house when the temperature drops, typically after dusk. In the winter external wall insulation will allow more of the heat that is produced in the home to be absorbed into the walls and then be released back into the building, rather than passing right through the walls to the air outside. External wall insulation will also reduce the absorbtion of heat from the outside by the walls in summer. This will help stop the home becoming too hot on the warmest days. In the winter internal wall insulation will do a good job of keeping the heat produced by your heating system in your home. However it is not as good at taking advantage of the thermal mass because of the barrier it creates between the heat in your home and the walls.

Damp and condensation

Can I stop the mould coming back once I've cleaned the walls?

There are a number of prodcuts you can use to clean mould caused by condensation from your walls. Look for a cleaning product that is fungicidal and follow the instructions to slow down the rate at which mould will grow back. If you need to redecorate you can buy special paint for rooms such as kitchens and bathrooms where excessive moisture is produced. This paint generally has a 'silk', slightly shiny finish and is tough, moisture resistant and easy to wipe clean.

I have no outside space to dry my clothes what can I do?

Drying clothes indoors can make problems with condensation and damp on the walls much worse. If you have no outside washing line or rotary hanger to dry clothes on consider using a local laundrette for drying. If you are a council or housing association tenant then your housing provider may well have local laundry facilities for you to use. Some manufacturers now make clothes hangers suitable for fitting to the sides of buildings which might be an option if you have no garden. If you absolutely must dry clothes indoors never hang wet clothes directly on the radiator. Use a clothes airer placed near a radiator in a room where you can leave a window open to allow the moisture to escape. It is also important to keep the door shut in any room where you are drying clothes to stop the mositure getting into other rooms in your home.

Loft Insulation

What depth should my loft insulation be?

The current recommended depth for loft insulation is 270mm (10.5 inches). If your insulation is less have than 150mm (6 inches) then it is worth considering getting it topped up.

Can I install loft insulation myself or do I need a professional?

You can chose to insulate the loft yourself. Mineral fibre can be an irritant so you should wear a full-body overall, gloves, eye goggles and a mask to cover your mouth. You should take great care when moving around in the loft and only undertake the work yourself if you are a confident DIYer.

Will it be possible to use my loft for storage after it has been insulated?

You can set aside part of your loft for storage where the insulation is only installed to the depth of the joist and insulated storage boards can be laid on top of the joists. If you want to use the whole loft for storage you will need to consider raising the height of the joist to allow the full 270mm depth of insulation to be laid. Do not compress insulation underneath loft boards - it makes it less effective as an insulator.

Will I need to empty my loft before the insulation installed?

Yes, you will need to ensure your loft is empty. If you are elderly or disabled you may be able to get help with clearing your loft through a local Care & Repair or similar agency.

Do I need ventilation in my loft?

Yes, lack of air flow in the loft space can lead to condensation which can cause damp. Loft insulation should never cover the eaves as this will restrict air flow. It may be necessary for the installer to add some extra air vents.

The loft was converted a long time ago. How do I make it more energy efficient?

You can insulate the pitch of the roof instead of the floor of the loft. There are a number of methods and products for doing this including using rigid insulation boards fixed between the rafters covered with plasterboard.

Underfloor insulation

What materials can I use to insulate my floor?

If your home is an older property you may have a suspended wooden floor. These timber floors can be insulated using mineral fibre or solid board insulation fitted between the supporting joists. If you have a new property which has solid concrete, a rigid insulation layer can be placed on top, or a good quality underlay and carpet can provide a good level of insulation.

Roof insulation

Can I insulate a flat roof?

Yes, a flat roof should ideally be insulated from above. A layer of rigid insulation board can be added either on top of the roof's weatherproof layer or directly on top of the timber roof with a new weatherproof layer then put on top.

Draught proofing

What can I do to reduce draughts?

There are many options to assist in reducing draughts, including draught excluders which can be fitted to doors and windows and flaps of letterboxes. Simple measures including placing heavy curtains at doors and windows, shutting them at night and tucking them behind radiators can also significantly reduce draughts as well as keep the heat in.

Heating controls

Is it better to leave the heating on all day at a low setting or only turn it on when I need it?

It is recommended that you only turn your heating on as and when you require it or set it on a timer. A well insulated home will warm up quickly and have a long cooling down time. If you leave your heating on all day you'll be spending money on fuel without feeling the benefit.

When should I set my heating to come on and go off?

Typically a home will take 30mins to warm up and cool down so it is best to set your central heating to come on 30mins before it is required and for it to go off 30mins before you no longer need it.

What temperature should I set the thermostat to?

Your room thermostat should be set at the lowest comfortable temperature which in the UK is typically between 18-21°C.

Night storage heaters

Are electric storage heaters as cost effective as gas central heating?

Generally electric storage heaters are more expensive to run than gas central heating. However to keep costs down homeowners with electric storage heaters should ensure they are on Economy 7 or Economy 10 tariffs to take advantage of lower, off-peak electricity prices at night.

Who should I contact to get my electric storage heaters serviced?

A qualified electrician would be able to service electric storage heaters.

Economy 7

How do I switch to an Economy 7 tariff?

The Economy 7 tariff is only usually recommended for people who use night storage heaters as their main form of heating. You'll need to have an Economy 7 meter installed so that your electricity use can be recorded at both 'day' and 'night' rates. You supplier may charge you for fitting a new meter. If you are switching tariff it's best to shop around to get the best deal. There are a number of independent online or freephone services that can help you.

Do some tariffs give a cheap rate for a few hours during the day?

Yes, some electricity suppliers offer an Economy 10 tariff where an additional few hours of off-peak electricity are available each afternoon. This gives the householder an opportunity to recharge their storage heaters to get some additional heat in the evening or run appliances like the washing machine or dishwasher at a convenient time and take advantage of cheap rate electricity.


Why are condensing boiler more energy efficient?

Condensing boilers are more energy efficient as they reduce the amount of heat that is wasted through the flue gases. Older boilers release exhaust gases through the flue at a very high temperature and this heat is wasted. However, condensing boilers have a larger or secondary heat exchanger and recover and use the heat from the exhaust gases.

Do I have to install a condensing boiler?

Condensing boilers are now specified by the building regulations for new gas and oil fired central heating systems, or if you are replacing your old boiler. This is because they greatly reduce carbon emissions produced by the heating system. They also reduce the amount of fuel need to keep the property warm and therefore give a significant reduction in fuel bills. However if there is no suitable external wall for the flue of the new boiler then it is possible for your heating engineer to apply for an exemption.

Will a condensing boiler be compatible with my existing heating system?

Condensing boilers can be fitted to most new and old systems. Your system may need to have a power-flush to remove sediment from the sysytem that could damage the new boiler. The heating engineer should size the boiler appropriately to meet the heat demand of your home wihtout over-sizing it so that it became inefficient and unnecessarily costly to run.

How can I find a reputable qualified heating engineer?

Gas heating engineers must be on the Gas Safe Register. Oil heating engineers may be registered with OFTEC but this is not a legal requirement. It is advisable to get at least three quotes from qualified heating engineers. A recommendation from a friends, family or neighbours who have had similar work done can also be helpful.

How can I tell how old my boiler is?

There is no easy way to find out how old your boiler just by looking at it. Records should have been left when the boiler was installed so this can be checked to find the age of the boiler. Alternatively, when the boiler has its annual service the heating engineer should be able to clarify the age of the boiler.

I want to use secondary heating to supplement the radiator in one room. What is the most efficient way to do this?

Room heaters are a good way of providing a heating supplement to radiators in one room as they provide focused localised heat in the specific room. Electric heaters can be costly so should be used to supplement the central heating and should not be used as an alternative to central heating.

Water heating

Is it more energy efficient to leave my immersion on all day for hot water?

There are a variety of water heating systems. As a rule it is more efficient to use these on demand, rather than leaving them on all the time. If your hot water cyclinder does not have a timer of its own you might be able to use a timer plug to control when your electric immersion comes on. If your central heating system heats up your hot water it is best to use a timer/programmer to time your space heating and your hot water at the same time. Hot water storage cylinders should always have an insulating jacket or solid foam around them to reduce heat loss.


What is low 'e' double glazing?

Low emissivity (low E) double glazing incorporates a very thin layer of metallic coating on one surface. This coating allows the sun's heat to enter the building but significantly reduces heat loss from the building by reflecting radiant heat back into the room.

What are trickle vents?

A trickle vent is a small adjustable opening in a double glazing unit that allows a small amount of ventilation in rooms that are double glazed. This is required because fitting double glazing reduces the amount of natural (or passive) ventilation in the home.

Why does condensation appear on my windows?

Air contains varying amounts of water vapour. Warm air holds more water as vapour than cold air. If warm moist air is cooled by a cold surface like a window pane it will not be able to hold the same amount of water vapour, therefore the water turns into droplets of liquid and collects on the cold surface as condensation.

Will double glazing eliminate condensation?

Double glazing cannot totally stop condensation from occurring however can considerably assist in preventing it from happening as the inner pane of glass will not be as cold as the outer pane therefore less water vapour may turn into water droplets.

How do I reduce heat loss through my old sash windows?

The cheapest method to reduce heat loss through sash windows would be to install secondary glazing. Alternatively, units can be purchased which are fitted and sealed. These incorporate double glazing to effectively reduce heat loss. Many double glazing companies now also offer double glazed replacement sash windows, however this can be costly. There are also draught proofing products designed specifically for sash windows.

What is secondary glazing?

Though not as effective at keeping the heat in as double glazing, secondary glazing is a much less expensive and less disruptive alternative. It is normally a thin sheet of glass or plastic film. Secondary glazing adds a second sheet to the window to improve thermal and sound insulation. It can be installed DIY.

Low energy lighting

Don't energy saving light bulbs take a long time to light up to full brightness?

Many years ago this would have been the case. However modern low energy light bulbs get up to full brightness very quickly. LED light bulbs are also becoming more popular. These are extremely efficient and light up instantly.

Are low energy light bulbs as bright as the equivalent tungsten light bulbs?

Low energy bulbs come in a range of power-ratings. It will tell you on the box what the rating of the equivalent old-fashioned bulb would be for low energy bulb you are buying.

Are there low energy light bulbs for all types of fitting?

Gone are the days when an energy saving light bulb had to stick out of the top of your lampshade. Low energy light bulbs are now available to fit the majority of fittings and come in a variety of shapes and sizes.

Is it better to leave energy saving light bulbs on or turn them off when I leave the room?

Even though low energy bulbs use far less electricity than the old fashion incandescent type it is still better to switch the light off if you are going to be out of the room for more than a minute or two.


How do I work out the running cost of an electrical appliance?

A kilowatt (kW) is 1000 Watts. If you know the rating of the appliance in kilowatts then you can simply multiply this by the length of time the appliance is being used (in hours) to give you its kilowatt hour (kWh) consumption. A kWh is the same as one unit of electricity on your bill. The price per unit will be on your bill. You could also plug your appliance into an individual appliance monitor. This will show the electricity consumption when the appliance is switched on. You can also get energy monitors that tell you how much electricity is being used in your whole house at any given time.

Which is more efficient for cooking - gas or electric hobs?

Electricity is around four times more expensive per unit than gas but you'll use fewer units cooking with electricity. A typical household might spend around £40 per year more by cooking with electricity as compared with gas. Also gas cooking appliances are traditionally more controlable than electric. However modern electric hobs heat up extremely quickly, reducing efficiency losses. With electric hobs make sure you match the pan size to the hob. Using a 6" diameter pan on an 8" diameter hob will waste up to 40% of the heat produced. Keeping lids on saucepans will allow you to turn the hob down and thereby save energy.

Where can I get an energy monitor?

Energy monitors are available from high street and shopping centre home-ware stores and can also be ordered online. Your energy supplier may also be able to provide you with an energy monitor. Some people can even qualify for a free energy monitor.

Comparing suppliers and switching tariffs

How do I know if I'm getting a good deal from my gas & electricity supplier?

Suppliers often change their tariffs and therefore if you want to be sure that you are getting the best deal it is worth checking comparison websites every six months to a year. Energy suppliers are now also required to provide you with assistance to ensure the tariff you are paying for is most suitable for your needs.

Can I get financial help towards high bills?

If you think your bills are too high, firstly discuss them with your energy supplier as there may be an alternative tariff which would suit you better. If you receive Pension Credit or another income related benfit then you might qualify for the Warm Home Discount which is a rebate from your fuel supplier on your electricity bill. Some fuel suppliers have charitable trust funds that help people who have fuel debt that they cannot pay off.

How do I complain about my energy supplier?

If you have a complaint it is best to try and resolve this issue by first talking to your energy supplier. If the matter is not resolved you can contact Consumer Focus or your local Citizens Advice Bureau who may refer your case to the Energy Ombudsman.

Reading your gas or electricity meter

On my bill the units I have used have the letter 'E' next to them. What does this mean?

The 'E' stands for 'estimated'. This means that your energy supplier has not actually read the meter but has instead made an estimate based on your past energy use. Estimated readings can be too high meaning that you'll be paying more than you should, or they can be underestimated meaning that you don't pay for all of the fuel you've used and end up having to pay the difference at a later date. This can lead to significant debt if you bills are being underestimate over a long period of time. It's always better to take an actual meter reading, so if you receive an estimated bill take a reading and contact your supplier promptly. There will be contact details on your bill. They will then provide you with a revised bill.

My meter is inside a locked plastic box outside my property. How can I read it?

The box can be opened using a special key which you can buy at most DIY or hardware stores. They are not expensive and have a universal size meaning they can be used on any meter box. You could ask your landlord or housing provider if they have one for your home. Alternatively the correct size socket spanner will also fit.

I think my meter is broken. What should I do?

If your meter is broken or damaged you should contact your gas or electricity supplier and they will send an engineer to inspect it and repair or replace it if necessary.

Room heaters

Are room heaters safe?

All heaters sold in this country must meet British Safety Standards. However, when using a room heater you should not leave them unattended for long periods of time. If you knock over your room heater be extra careful how you pick it up as it may be extremely hot to touch. Never put a room heater close to something flammable as this is a potential fire hazard.

Warm Home Discount

I have a pre-payment meter, can I still receive the discount?

Yes. If you are eligible, you will be sent a voucher that you can use to top up your meter credit

Is my electricity supplier taking part in the scheme?

There are 21 suppliers taking part in the scheme. Give our Home Energy Team a call to check if your supplier is taking part - 0800 082 2234

I receive guaranteed element of pension credit but I am not the bill payer. Do I receive the discount automatically?

No. If you are not named on your electricity bill you will not be paid automatically and will need to make a claim. Give our Home Energy Team a call to check if your supplier is taking part - 0800 082 2234

I receive guaranteed element of pension credit and I have recently switched supplier. Can I still claim the discount?

Yes. If you have changed electricity supplier in the last 6 months the company who supplied you with electricity up to the 12th July 2015 is responsible for paying you the WHD. If you have left your supplier after this date they should send you a cheque for £140.

I don't receive the right benefit, what can I do?

It’s worth taking the time to check your benefit entitlements, as in some cases while the additional benefit itself pays a relatively small sum, if it qualifies you for the WHD the total benefit is substantial. If you haven't reviewed your benefit for a while, speak to our Home Energy Team about a benefit entitlement check. Call 0800 082 2234.

How is the Warm Home Discount paid?

It depends on how you pay for your energy.

If you pay by either direct debit, quarterly billing or fuel direct* the £140 will be credited to your electricity account, if you have duel fuel it will be credited to that account

If you pay by key/prepayment meter you will be sent either a letter that contains a code or vouchers. You would take this to the Paypoint where the code on the letter or the voucher will be scanned and £140 will be credited to your account

*please be aware that the payment of £140 may clear your debt and you may be taken off the fuel direct method of payment

What should I do if I am not eligible with my current supplier but I am eligible with a different supplier?

You could always switch to the supplier you are eligible with. You will need to check with your current supplier to see if there are any cancellations fees for leaving early. However, even if there are cancellation fees, these are likely to be around £30 whereas the Warm Home Discount is £140, so you would still be better off by doing this.

Please also be aware that it will take a couple of weeks for your supply to switch over to the new company and there is the risk that they may close to new applications before you have switched over.

Why is the rebate applied to my electricity account when I use gas to heat my property?

For administration purposes it is easier to pay this rebate towards one fuel. In the UK not all houses have a gas connection but nearly all have an electricity connection it was decided that this is how it would be paid.

Can I get the Warm Home Discount applied to my gas account instead?

No. It will only be credited to your electricity account or your duel fuel account.

If the Warm Home Discount means that you have a large amount of credit on your electricity account you could ask your energy supplier for a refund for this but it will be their decision.

Need more help?

Depending on where you live, and who you buy your energy from, we can help you with grants and support.

Need advice about saving energy? Want help with grants and support?

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