Where am I losing heat in my home?

Where am I losing heat in my home?

We must get asked this question about 100 times a day!

It is obviously fundamental to everything we do here at TheGreenAge; if we can show our customers how to slow down the rate at which heat leaves their homes then we can help save them money.

In this blog, we are going to take a look at some of the basic principles behind this – what should you do to stop the heat loss in the home? And in what order? What provides the best cost benefit?

All is revealed below, but we haven’t gone in to too much detail. Click on the hyperlinks to take you to different parts of the website, where you can learn much more about the particular item/s you have an interest in. Enjoy – and as always let us know what you think in the comments below!

The Thermal Envelope

Give or take, about 25% of the heat produced by your boiler will escape through the roof of your home.

About 35% of the heat will escape through the walls and through gaps, in and around windows and doors, and about 10% of heat will disappear through the floor. Collectively the roof, walls (+ windows and doors) and the floor are known as the thermal envelope.

If you can slow this movement of heat from inside the house, through the thermal envelope, to the external environment, you can dramatically reduce your energy bills. In modern houses, building regulations stipulate that homes have to be built to do just that – but how exactly do you go about retrofitting these solutions into older homes?

Stop heat leaving through the roof

Install loft insulation in the roof space. This is the no.1 best thing to do for energy efficiency in the home – it is really cheap, easy to do and the payback can be just two years or less.

You will need to decide if you want a warm loft or a cool loft, and what exactly you want to do with the loft space (for example do you want to store boxes up there or be able to walk around?)

In addition you need to decide the insulating product you want to use – mineral wool, sheep wool, rigid insulating board or even newspaper. There are lots of options for you to consider, but we love these recycled rolls from EarthWool.

Stop heat leaving through the walls

Walls tend to come in two forms – solid walls and cavity walls.

As a rule of thumb, properties built prior to 1930 will have solid walls and anything built after will have cavity walls.

Cavity walls are incredibly easy to insulate; the walls are simply injected with insulating material, which slows the movement of heat across it. This is cheap and well worth doing, again with a relatively quick payback – however a professional will need to install this for you.

If you have solid walls, things are more complicated – there is no cavity that can be filled, so the walls need to be insulated either externally or internally. This is costly to do, and externally it involves cladding (so you will lose the feel of the brick). Meanwhile if you opt for insulation internally, you will lose some floor space. There is a grant available to help cover some of the costs of getting solid walls insulated – it is called ECO.

Insulating your walls is well worth doing since it accounts for the biggest source of heat loss – click on the hyperlinks within the sections above to learn more about the processes involved.

Windows – important, but not as influential as you may think!

Double GlazingWe get lots of calls about windows, people want to replace them with double glazing to help stop heat loss and keep the home warmer.

There are two issues to consider here – firstly think of the area of glazing in your home compared to the area of actual wall. Normally there is substantially more wall area than glazing, so always target the walls first. Secondly, double glazing is expensive – to replace a wooden sash window with a wooden double glazed unit may cost you £1200 PER WINDOW!

So what is the energy saving from changing one single glazed window to double-glazed?

Perhaps £5 – £10 per year

That is not to say it is not worth doing, double-glazing will improve the comfort of the home by stopping heat loss, cold draughts and improve soundproofing. However, from a cost perspective you may want to consider other measures first. Secondary glazing is a simple and easy alternative; companies like Ecoease make bespoke secondary glazing at a fraction of the price of traditional double glazing – you can find them here.

Draught proofing – cheap, cheerful and quick payback

door draught prooofingDraught proofing is often overlooked, but think about an open chimney in your home. Cold air will rush in and the expensive warm air that your radiators have created can simply rise up and out of the chimney. If you draught proof the home effectively this can be prevented.

Draught proofing can be installed around doors, windows, loft hatches, floorboards – in fact in all sorts of places, so click on the links to find out more about your specific problem areas in your home.

How to stop heat leaving through the floor

Standing on a cold, draughty floor is miserable, but you can do something about it! Insulating floors will stop heat escaping but if you are looking something a little bit more, you can install underfloor heating in conjunction with a traditional boiler, or better still a heat pump. This will allow you to heat the home and do away with radiators forever! Insulating floors is a relatively simple process and like walls, there are two main types – solid floors and suspended timber. Find out how to insulate them by clicking  here!

Quick mention of U-values

When exploring energy efficiency in the home – you may encounter the term U-value. It is not one to be scared off, it actually simply refers to heat loss.


The lower the U-value the better, so an unfilled cavity wall might have a U-value of 2.0 W/m2k, while filling the cavity might take the u-value down to 0.2 W/m2k.

You’ve done all that – what next?

So now you have insulated the home, less heat is going to escape – or at least the rate at which it escapes into the external environment will have slowed.

Now it is time to consider the heating system. The more efficient the heating system, the less it will cost to run your house.

When to upgrade your heating system

Energy efficient BoilerMost people in the UK have a mains gas boiler – but just how efficient is it? A new energy efficient condensing boiler should be 90% + efficient. This means it will convert 1 unit of gas into 0.9 units of useful heat. A boiler 10 years old or more might be just 65% efficient – so depending on your energy usage it may be worth installing a new one.

Other more efficient heating solutions include air and ground source heat pumps, and with these you will soon be able to benefit from the generous Renewable Heat Incentive scheme (RHI), which will provide you with a payment for every unit of hot water you produce.

You might like to consider Biomass boilers, these run on sustainable biomass pellets, so are ‘carbon neutral’. Installing a biomass boiler will also allow you to take advantage of the RHI.

Infrared Heating Panel MirrorInfrared heating panels are another great way to heat your home. These panels emit infrared (like the sun – don’t confuse with harmful UV!) to heat spaces.

These are more efficient that traditional convection heating systems (radiators) since they don’t use air as the medium for heat transfer. Instead the infrared will travel until it hits a solid body and then warm that directly. The panels warm up quicker and as soon as they are up to temperature you feel the warmth, compare that to a radiator and how un-reactive that is!

If you only have access to electricity (no mains gas), these infrared panels are definitely worth considering.

The importance of heating controls

The importance of heating controls should not be underestimated. Typically there are three technologies that make up heating controls in the home, thermostatic valves on radiators (normally known as TRVs), thermostats and programmers. If you don’t have heating controls, but you do everything else we have listed above you are going to have a very hot home and not really save much money.

The reason for this is that you will use the same amount of gas – but the heat won’t be able to escape. Ideally the heating system turns off automatically when the temperature reaches a certain point – normally about 200c. This means that the boiler (or whatever heating system you have in place) will turn off and you won’t be continue burning gas unnecessarily.

<<< Read More About The Most Efficient Way to Use Central Heating >>>

Finally – producing your own energy

Solar PV being installedEveryone likes the idea of being energy self-sufficient. Having solar panels, wind turbines or hydro electric that provide you with all your electricity means you can wave goodbye to the energy companies. In practise this is very hard due to the limitations of energy storage. However these technologies will help you reduce your reliance on the grid. Electricity is expensive; it has gone up 10% each year for the last 8 years. Any way of lessening your demand on grid electricity can only be beneficial to insulate yourself from future price increases.

So there you have it  – our whistle-stop tour of how to limit the amount of heat leaving your home, become more energy efficient, save money on bills and do your bit for the environment. Seems a bit of a no-brainer to us!