In this article

Draught proofing windows and doors - what products are available?

Benefits of energy efficient windows and doors

What is an energy efficient window?

Costs of savings of energy efficient windows

How much can I save with energy efficient windows?

What is an energy efficient door?

Costs and savings of energy efficient doors

How to choose an energy efficient window or door

Other ways to insulate the home

In any property, a certain level of heat loss will occur, which means that heat escapes through areas such as the roof and through poorly insulated walls. This amount of heat loss is determined by things such as the level of insulation in the home, or the amount of draught proofing measures installed. Ultimately, a home which has a poor energy efficiency rating will experience higher heat loss and higher bills. So, it’s important to take steps to increase the energy efficiency of the home where you can. 

While upgrading insulation is one of most important home improvements works to consider, windows and doors can also be a source of heat loss. For example, if you have single glazing or older exterior doors, these could be letting draughts through and cost you money. 

The good news is that there are many different options on the market. Ranging from double and triple glazing to A++ rated doors. Read on to find out more and learn about the costs, savings and benefits to help you make an informed choice.  

Draught proofing windows and doors – what products are available?

Draught proofing for windows and doors is a great place to start if you’re not quite ready to make the investment on replacements. These measures are typically very affordable (from as little as £6) and easy to install as a DIY project. Once installed they will help reduce the amount of heat loss and draughts entering the home. There are several different draught proofing products available for use with windows and doors, which you can find in all hardware stores. Here are the most common.

Draught proofing strips: For windows that open, you can buy draught proofing strips which stick around the window frame and fill the gap between the window and frame. These come in the form of self-adhesive foam strips or metal or plastic strips with brushes attached. The longer lasting strips tend to be those that have brushes attached but do have a slightly higher price tag. You should always make sure the strip is correctly sized for the window to avoid it getting crushed.  

Sealant: Silicone sealant works well for windows which aren't designed to open but may still have gaps in the frame which cause draughts. A sealant gun is typically used with the sealant being applied into the gaps. This stops the draughts entering. Sealant is affordable and easy to apply with plenty of online tutorials available.  

There are also some door specific measures to consider... 

Keyhole and letterbox cover: You can purchase a purpose made metal disk to fit over the keyhole cover and consider a flap or brush for the inside of the letterbox.  

Draught excluders: For gaps around the bottom of doors, consider a brush draught excluder. Make sure this is measured to the correct size.  

The above measures just scratch the surface when it comes to the possibilities of draught proofing. If you’d like to learn more, you can check out our full guide to draught proofing.

Benefits of energy efficient windows and doors 

There are several key benefits that installing energy efficient windows and doors can come with. From increasing comfort in the home to helping you save on energy bills.  

Increased energy efficiency: Energy efficient windows help reduce heat loss in the home. This means your heating system won’t have to work as hard or be on for as long to produce a comfortable temperature. 

Reduced noise pollution: Double and triple glazing is sealed, meaning it is highly effective at reducing medium to high frequency noise. This creates a more peaceful, private and comfortable environment in the home.  

Lower energy bills: As a result of the increased energy efficiency and reduced heat loss, you will typically find that you experience savings on energy bills. Savings will vary depending on the size of the home and products chosen.  

Lower carbon footprint: They can help you to reduce your heating carbon footprint and to combat climate change. If you have a fossil fuel powered heating system such as a gas boiler, this will be used less resulting in less carbon emissions being released into the atmosphere.  

Reduced condensation: Both energy efficient windows and doors help to reduce the risk of condensation. This occurs when a cold surface and moist air meet and can result damages to the frame or parts of the room. The modern frames and materials help to combat this.  

Improved thermal insulation: Energy efficient windows have benefits all year-round, not just during the winter. The sealed gap between the panes of glass provides an extra layer of insulation. This gap reduces heat loss during winter, keeping the home warm and comfortable. In summer, the windows help to keep the heat outside, keeping the home cool inside. Energy efficient doors can be installed with insulation material fitted to help with this too. 

Increased value of home: Potential buyers want to purchase a home that is efficient and cheap to run. The increased level of energy efficiency combined with having a set of modern windows or doors will be an attractive selling point. 

What is an energy efficient window? 

Windows come in all shapes and sizes and have varying levels of efficiency. The chances are if you have an older single glazed property, and the windows haven’t ever been replaced, then you could be experiencing heat loss through these. Upgrading to energy efficient windows is a great way to reduce carbon footprint and energy bills, but what exactly makes them different?  

Energy efficient windows look like an ordinary window but use either double or triple glazing and are made of two or three panes of glass sealed in a single unit. These panes of glass are then surrounded by a frame, which may be uPVC, wood or another material.  

The glazing of an energy efficient window is rated according to its ability to reduce the amount of heat that can pass through the window, the capacity for sunlight to travel through the glass unit, and the capacity for air to move through the unit. Special design features such as Low-E glass help to keep heat trapped in the home.  

Energy efficient window materials 

You will need to decide whether to opt for double or triple glazing and your installer will be able to help you with this. Here is a quick summary of how both types are designed and the other elements that make up an energy efficient window.   

Double glazed: These have two panes of glass with a small gap in between (around 16mm). 

Triple glazed: These have three panes of glass and two gaps. In theory this can make them more effective at insulating, however it does depend on the overall efficiency rating. The gaps between the glass panes are filled with air, or an inert gas such as argon. The air or gas is completely sealed. A 16mm thickness between the gaps is usually the optimum amount.  

Glass: The most energy efficient type of glass for double and triple glazing is low emissivity (Low-E) glass. Low-E glass has a microscopically thin coating of metal oxide on one of the internal glass surfaces. This coating reflects heat back into the home but still lets in the light from outside. 

Pane gaps: These gaps are spaced out around the inside edges of the window to keep the panes of glass apart. More efficient windows will typically have pane spacers which contain little to no metal. These are known as ‘warm-edge’ spacers. 

Frame materials  

The window frames come in several different options. The design and the material chosen will have a direct effect on heat loss. The best performing windows will typically come with frames in the following materials.  

uPVC: These frames require no regular maintenance and can be recycled.  

Wooden: These frames can be better for the environment but do require maintenance. You will typically find wooden framed windows in areas where other types of materials are unable to be used. 

Aluminium or steel: These frames are slim and long lasting. They can also be recycled like with uPVC.  

Composite: These frames have an inner timber frame covered with aluminium or plastic. This reduces the need for maintenance and makes the frame more weatherproof. 

Costs of energy efficient windows 

The increased energy efficiency will help you to make savings on energy bills and reduce carbon footprint. The initial investment required can be quite high and it does take a while to pay back, however you could be making energy bill savings year-on-year. 


Costs do vary significantly depending on the materials, style and size of home. If opting for uPVC windows these tend to be cheaper. A set of A-rated uPVC windows for a semi-detached house will cost around £4,250, compared to £15,000 for A-rated hardwood windows. We would always recommend shopping around and getting a few different quotes to gather an idea of pricing.

How much can I save with energy efficient windows? 

Savings on energy bills 

Energy efficient windows allow you to make great annual savings on energy bills. These savings will help you recoup your initial investment in the long term. For example, if you have a semi-detached gas heated property and replaced single glazing with A-rated double glazing, you could save £75 per year. If you replaced single glazing with A++ double glazing in the same property, you could save up to £95 per year.

Carbon footprint savings 

As well as saving you money, energy efficient windows can help you do your bit for the planet. Increasing the energy efficiency of the home will allow you to cut your carbon footprint and reduce carbon emissions. You could save up to 330kg of CO² when replacing single-glazed windows with A-rated double glazed in a gas heated, semi-detached property. In the same property, if you opted to replace single glazed windows with A++ double glazed, you could save 405kg of CO² per year. That's the equivalent of over 180 litres of diesel.

What is an energy efficient door?

Much like with old windows, a key problem with old doors is their energy efficiency level. If they let draughts into the home, or aren't made from modern materials, they could be costing you money on your heating bills. As well as older doors, those that are not properly insulated, fitted or sealed could be causing air to leak through. 

Energy efficient doors look like regular doors but are an effective way to increase the thermal performance of the home. They are specially designed with materials that reduce heat loss and keep the home warm.  Materials for energy efficient doors vary and can be designed to match the home. They range from oak to aluminium, and any glass on the door will typically be double glazed.  

Energy efficient door materials 

When considering which door to go for, there are some materials and parts of the door that should be considered, here’s a quick summary of them.  

Door: The material that the door is made from plays a big part in ensuring energy efficiency. The most common materials include fibreglass, aluminium or wood. Composite doors are also becoming increasingly popular and are made up of several materials, including uPVC and solid timber. These composite doors usually have A+ efficiency ratings and are known to be ultra-efficient.  

Frame: The door frame is the outer framework supporting the door. Door frames can be made of wood or aluminium and are made to blend seamlessly with your home. Like with the door itself, composite door frames are considered to be the most energy efficient and durable.  

Glazing: Like with windows, you will need to choose between double or triple glazing. You should also keep an eye out for any doors which feature low emissivity (Low-E) glass. 

Insulation: The exterior doors of the home should have some form of insulation, even if they are made from an already energy efficient material. Insulation may include materials such as polyurethane foam which works to increase the thermal resistance of the door further.  

Weatherstripping: This runs across all the edges of the door and ensures that it’s properly sealed against the elements. This weatherstripping should be airtight and the best door frames come installed with it. You can even purchase strips to install yourself and add extra protection to the door. 

Costs and savings of energy efficient doors 

Energy efficient doors do tend to be slightly cheaper to install than a whole new set of windows, but pricing will depend on the materials chosen. The initial investment can be recouped in the long term as a result of reduced energy bills from improved energy efficiency in the home.  

Costs will vary depending on a few different factors including the size and material of the door, as well as glazing option chosen, the more efficient the door, the higher price you will typically pay. Current industry pricing shows that for a uPVC front door you can expect to pay £800 including installation for A++ rated triple glazed. Composite door prices are 50% more expensive than white uPVC. Timber door prices are 75% more expensive than white uPVC. As always, we would recommend shopping around and getting a few quotes, as some installers may charge more for installation of the same door.

In terms of energy bill savings, this again will vary greatly depending on the type of door chosen. According to the Energy Saving Trust you could save up to £110 per year for a detached home. It’s always worth having a chat to your installer around the typical savings to expect.

How to choose an energy efficient window or door 

So, you’ve decided you like what you hear, and you want to reap the benefits. You’ll need to decide on an installer and which windows or doors to go for, as not all are created equal. There are some key things to consider when deciding, such as how efficient they will be and how to choose an installer.  

What are window and door energy efficiency ratings?  

There are multiple factors which contribute to the energy performance of a window or door, and you want to make sure you’re getting a good return on your investment. Thankfully, there’s a helpful ratings scheme which will help you choose the most efficient for your home. Window and door energy ratings are determined by the British Fenestration Ratings Council (BFRC), who perform independent assessments of windows and doors to determine their performance.

An energy-ratings scale is used by the BFRC for manufacturers to show the energy efficiency of their products. This scale rates windows and doors from A++ to E. The entire product is assessed for heat loss, draughts and solar gain and given a rating. This rating represents the overall impact of fitting that product in the home. To choose the most efficient window or door, look at the BFRC rating. The closer to A++, the more efficient it will be. 

What is a U-value?

In addition to the BFRC rating, windows and doors will also come with a U-value. The U-value measures the rate of heat transfer through a structure. The lower the u-value, the lower the rate of heat transfer. A u-value isn’t a complete measure of how efficient a window or door is but checking this and the BFRC rating is always the best bet.  

Finding an installer 

Because of the upfront investment, you want to make sure your install is of the highest quality. The Glass and Glazing Federation (GGF) is a membership-based organisation where members sign up to a consumer code. This should guarantee excellent customer service and workmanship. If you use a GGF member and you’re unhappy with the work, you can use their free reconciliation service. We would always advise checking the GGF website for a list of members in your area and getting a few quotes.

The British Fenestration Rating Council (BFRC) website has a 'Find-a-product' search facility so you can find a door or window by energy rating for your postcode area and find authorised and reputable installers.

Other ways to insulate the home

Roof and loft insulation

By insulating the roof and loft of a home you could make savings of £275 per year on energy bills and eliminate one quarter of total heat loss in the home. 

Cavity wall insulation

This is the construction of an inner and outer wall of the home, with a small space in the middle known as the cavity. This cavity between the inner and outer wall of the home can be filled with insulation materials, which reduces heat loss and could save you up to £305 per year on annual energy bills.   

Solid wall insulation

If solid walls are installed in the home, they too can be insulated. Solid walls contribute to 45% of overall heat loss in the home, so insulating them can be a great way to reduce heat loss. You could even save up to £375 by doing so.