Millions of pounds' worth of energy escapes from our homes every year because they are poorly insulated.
So insulating your home properly is one of the best ways to reduce your energy bills and help you stay warm. And the good news is that it doesn't need to cost the earth.
In fact, if you save energy, you're helping save the earth's precious resources!
How does insulation work?
Insulation helps prevent heat escaping from your home during cold periods AND helps it to stay cool when the weather is very hot.
That's because it absorbs heat and slows down its movement in or out.
Types of insulation
Most of us are familiar with is loft insulation, which generally comes rolled up in blanket form and is made from recycled glass or sheep's wool.
There is also loose-fill loft insulation, which can be made from cork granules, mineral wool or cellulose fibre, and sheet insulation - firm boards designed to insulate the sloping sides of the roof.
Cavity wall insulation could also save you a lot of money if your home was built after 1920.
That's because the external walls of more recent homes are made of two layers with a gap - or cavity - between them. And filling that gap with cavity wall insulation means keeping the warmth in and saving energy.
If you have solid walls, you can also get solid wall insulation.
It is more expensive than cavity wall insulation, and involves fitting rigid insulation boards to the wall, or building a stud wall filled in with mineral wool fibre.
External wall insulation involves fixing a layer of insulation material to the outside of the wall, then covering it with a special type of cladding.
How does heat escape and cold get in?
There are several ways that heat can escape from your home.
Not only can it move through walls and metal via a process called conduction, it can also be transferred from one place to another by the movement of fluids or air via convection.
This is when heated air rises, allowing cooler air to replace it until the warmer air above falls again.
Draughts also result in heat loss by letting warm air out and cold air in.
And heat can also escape via radiation and evaporation, for example, when it rains on a hot day and the water evaporates from your roof causing the temperature inside your home to fall.
Where should I insulate my home?
Insulating your loft is key to keeping your home at the desired temperature.
You should also get cavity wall insulation if possible, and watch out for draughts around doors and windows.
Draught excluder packs are available from most DIY stores for as little as £60 and could cut your heating bills by £25 a year.
How much can I save on my energy bills?
Insulating a loft that has no insulation at all could save you up to £250 a year, according to the Energy Saving Trust.
And draught proofing around windows and doors could save you £50 a year in energy costs.
Cavity wall insulation, meanwhile, can also save you up to £250 a year if you live in a detached house.
And if you sell your property, making it more energy efficient should increase its market value too.
Do I need planning permission for insulation work?
As a general rule, you don't need planning permission to insulate in your home.
However, check with your local council first if you have a listed property, or you live in a conservation are and want to fit external wall insulation or glazing.
Can I get insulation for free?
There are plenty of insulation grants and offers available from energy suppliers, which have been set energy efficiency targets by the government.
In many cases, you can therefore get cheap or even free insulation fitted - whatever your financial circumstances.
For those on lower incomes and benefits, there are also Government schemes available, linked to the Green Deal.
You can find out more about the Green Deal here or by calling the Energy Saving Advice Service on 0300 123 1234 (or 0808 808 2282 in Scotland).
Good and bad types of insulation
The most effective types of insulation tend to look a bit like sheep wool, but are in fact made of mineral or glass wools.
Paper and wood are also good insulators, although paper must always be fireproofed before use.
However, metals such as aluminium, copper and steel, and building materials such as brick, stone and concrete, transmit heat and allow it to escape.
How do I recognise good insulation?
To find out how effective the insulation you are planning on using is, you will need to check the R-values on the packaging. The higher the R-value, and the more effective your insulation will be.
If you are doing major works, you should also check the U-value. This measures the amount of heat lost via the material you are using, meaning the lower the value the better for you.
Other ways to reduce energy bills
Properly insulating your home can slash your energy costs. But so can making sure you are on the right deal.
You can compare tariffs online through MoneySupermarket's energy channel to find the best deals quickly and easily.
†10% of customers could save up to £670. MoneySuperMarket Data, May 2016