Insulating



We all want a warm, comfortable home, and paying extra to heat the world outside is no-one’s idea of a good time. As luck would have it, the best ways to cut your carbon at home are also the best ways to banish the chills. Here's what you need to know...


Loft insulation

  • Typical cost: £250
  • Typical carbon saving: 800kg
  • Typical payback: 1-2 years

If you’re anything like us, going in the loft fills you with dread. But if it’s not well insulated, a quarter of your home’s heat (not to mention your gas bill) could be going through the roof.

Sticking in a decent layer of insulation can save up to a tonne of carbon a year - that’s 10% of the typical UK footprint in one go. You can even do it yourself in an afternoon. Loft insulation costs £200-300 to do properly (to the suggested depth of 270mm), but it’ll pay for itself in a couple of years.

More info from the Energy Saving Trust

Cavity wall insulation

Filling the gap

  • Typical cost: £250
  • Typical carbon: 610kg
  • Typical payback: 2 years

If your house was built after about 1920, you’ve probably got cavity walls. This is just a wall that’s hollow - two layers of bricks or blocks with a small space in between. Fill the space with insulation, and good things happen. Not only is it cheap and easy to do; it can also take about a third off your heating bill.

The hardest bit about cavity wall insulation is working out if you’ve already got it. To find out if you have a cavity wall, look at the pattern of the bricks. If you have a cavity wall, the best way to check if it’s already insulated is to look for small circular marks left in the brickwork by the drills the installers use. Alternatively, ask a local insulation service to come and take a look. Call the Energy Saving Trust free on 0800 512 012 for help finding a reputable installer near you.


See how it works.
Find out more.

Solid wall insulation

Insulation for older houses

  • Typical cost: £5,500 - £8,500 (internal) £10,500 - £14,500 (external)
  • Typical carbon: 2000kg
  • Typical payback: Varies, but normally at least 10 years

If you don’t have cavity walls, all is not lost. Adding an insulating layer to the wall itself isn’t straightforward, but it makes a huge difference. Internal insulation Internal insulation involves adding an extra layer to the inside face of exterior walls – either boards within a narrow wooden frame or a clever flexible material called Sempatap. Sempatap is rolled on almost like wallpaper, and can be decorated with any finish. As an added bonus, it keeps condensation and black mould at bay. The typical cost will be around £45 per square metre plus the price of redecoration. DIY fiends can save money by doing the installing themselves, and you can keep costs down by insulating only the most frequently used (or the coldest) rooms. External insulation External wall insulation involves adding a thick coating (5-10cm) to the outside walls of your house. This costs a fortune if done in isolation, but makes a lot of sense if you’re already having your walls repaired. Exterior insulation will drastically change the look of your building, so if you live in a conservation area it might be a non-starter. Elsewhere, you can apply different finishes to get the look of your choice.


Find out more

Floor insulation

Insulation underfoot

  • Typical cost: £90
  • Typical carbon saving: 250kg
  • Typical payback: 2 years

People rarely think about insulating their floors, but some homes lose as much heat to the ground as they do through the windows. For houses with wooden floors on the ground level, insulating under them is a fairly simple process. Some or all of the boards are taken up and the insulation is either rolled or blown into the space underneath. If you’ve got solid floors it’s a bit more complicated. Adding the insulation is easy enough (sheets of material are layed on top of the concrete) but the floor will be raised slightly so you’ll need to shorten doors and raise your skirting boards. On the plus side, underfloor insulation really helps the room to warm up quickly when you turn the heating on.


Double glazing

Don’t throw money out of the window

  • Typical carbon saving: 720kg
  • Typical money saving: £140

After all those dodgy salesmen and annoying ads on local radio, double glazing has a bad reputation. But if your windows are of the ancient and rickety persuasion, changing them will work wonders. New windows don’t come cheap, but after sorting your loft and walls, it’s the most effective bit of insulation you can do. When you’re shopping for double glazing, make sure whatever you choose has a good energy efficiency rating. You can find out by checking the label, or looking up the company on the BFRC website. A high rating just means it’s better at keeping heat in. If you can’t find the label, anything with the Energy Saving Trust logo on it is a good bet.

More on double glazing

Window film

Double glazing on a budget

  • Typical cost: £50

This sounds a bit crazy, but bear with us. If you have old leaky windows, a small budget or an unenlightened landlord, window film is a brilliant alternative to double glazing. Fitting it is pretty straightforward, and takes about half an hour per window. At about £3 a window, it’s possible to do the whole house for under £50.

Step one is to attach a thin sheet of a special clear plastic to the inside of your window frame using double-sided tape. So far, so crinkly. But here’s the good bit. Run a hairdryer over the plastic and it shrinks, making the creases vanish as the film pulls tight. After five minutes or so, the plastic should be almost invisible. Fitting tips:

  • Clean and dry the window frame before applying the double-sided tape - use a bit of normal sticky tape to pick up any bits of dust you might have missed.
  • When tightening the film with the hair dryer, work from the outside inwards for the best results.
  • If you’re doing a bigger window, make sure you have a glamorous assistant to give you a hand.
  • If the wrinkles return, you can always use the hairdryer to get rid of them.
Video fitting instructions
A dedicated UK stockist
Window film on Amazon

Hot water tank jacket

Keep it snug, keep it efficient

  • Typical cost: £12
  • Typical carbon saving: 190kg carbon
  • Typical payback: 5 months

This is a really simple one. Put a good jacket (at least 75mm thick) on your hot water tank, and it’ll pay for itself in a few months. Easy. For extra points, add some insulation to any exposed hot water pipes you can find around the tank or in the rest of the house.

Buy a tank jacket here
Buy water pipe insulation here

Radiator panels

Heat the room, not your walls

  • Typical cost: £40 for 20 panels

These humble bits of plastic sit behind your radiator with the socks, takeaway menus and bits of fluff, quietly saving you energy. They work by reflecting the radiator’s heat away from the wall and out into the room. There’s no need to take the radiator off the wall - the panels slot in behind and stick to the wall using double-sided tape. They work especially well on outside-facing walls that aren’t insulated; if you really go to town and do every radiator in the house, you can save 15% or so on your heating.

Video fitting instructions Radiator panels on Amazon

DIY draughtbusting

Insulation can be fun. No really! Well, maybe.

  • Typical cost: £90
  • Typical carbon saving: 150kg
  • Typical payback: 3 years
Draughtproofing your house is one of the easiest bits of insulation you can do. It’s straightforward, affordable, and you can do as much or as little as you feel like. You can even get the kids involved.
There are about 40 common sources of draughts and heat leakage, some much easier to sort out than others. Start off with the obvious ones:
  • Close up any open chimneys using a fireguard, a chimney balloon, or a specially designed panel. Ask at your local DIY store for the best solution for your chimney. Whatever you put up there, don’t forget to take it out before you light the fire!
  • Add weatherstrips around windows, outside-facing doors, and your loft hatch.
  • Use a tube of normal household sealant to fill in gaps between the floor and the skirting board, around the window frame, and anywhere else you spot a gap that could let cold air in.

Tracking them down: Some leaks will be immediately obvious (if you can see daylight through it and it’s not a window, it could probably use some insulation), but some are harder to spot. On a windy day, hold an incense stick near a suspected draught source - the moving smoke will be a dead giveaway. If you want to catch them all, arm yourself with an incense stick and use this list of air escape routes.

Buy draught excluders here
Buy sealant here
Buy incense sticks here ;)

Good to know

Paying for it

Many of the grant schemes offering free loft and cavity insulation have been phased out to make way for the Green Deal loan scheme, but it's worth calling your council to see if there are any local schemes still running.

Leakage vs ventilation

It’s important to have a flow of fresh air coming into your house, especially in the kitchen, the bathroom, and anywhere else that can get steamed up. But you should able to control how much you let in, and when. That’s why the gaps that produce draughts don’t make for good ventilation - it’s much better to stop them up and install slot vents and extractor fans where they’re needed.


Every little helps

Some of these options don’t come cheap, but remember that it doesn’t have to be all or nothing. Your best bet here is to prioritise; start with the coldest or most regularly used rooms, then keep going as far as your budget will allow. A little is always better than nothing.

If your home is less than 10 years old, you’ll probably already have good wall and loft insulation, so you might get bigger cuts from other areas of your carbon footprint.

Lots of these tips are pinched from The Rough Guide to Green Living, by 10:10’s resident carbon expert Duncan Clark.