How energy efficient windows help reduce heating bills

1st September 2022

How energy efficient windows help reduce heating bills

Did you know that around 22% of the UK’s Carbon Emissions come from our homes?

As we all become ever aware of our need to become more energy efficient, we turn our attention to what we as individuals can do at home. Making a more energy efficient home needn’t be difficult, starting with the simple things like switching lights off when not needed and minimising our use of household utilities like the kettle and washing machine.

In this article, we will show you how making a few changes in your home, including installing high quality windows and doors can help you save energy, minimise your carbon footprint and save you money on your energy bills.

Top 5 ways to improve home energy efficiency

  1. Use less electricity
    The Energy Saving Trust calculated that the average UK home spends around £35 a year, just by leaving electrical goods on standby. Although we all have electrical appliances such as a fridge and freezer that need to stay on day to day, many of us are prone to leaving multiple items plugged in and on standby. So the first thing to do is switch off those items that don’t need to be on and unplug them!

  2. Upgrade your lightbulbs
    If you are a household that still uses old incandescent lightbulbs, it’s time to change that. It’s acknowledged that old lightbulbs are one of the least energy efficient items in a house. By replacing old bulbs with LED bulbs, you could save yourself up to £37 a year on bills and cut 135KG of carbon dioxide from your carbon footprint. That’s the same as using nearly 43 litres of petrol!

  3. Choose Energy Efficient Appliances
    When it comes time to update old appliances, make sure to opt for products that come with a high energy efficiency rating. Switching to energy saving appliances is a sure-fire way to save both energy and money.

  4. Cut down the cost of your heating
    Hot water and heating are one of the biggest costs in running a home, making up almost 4/5 of most fuel bills. A way to combat heat loss is to improve the energy efficiency of your heating system. By replacing any boiler older than 15 years old or G rated with a new A rated, eco-friendly boiler, you could reduce your bills by up to a quarter. By introducing a new boiler, only using your heating when necessary and ensuring you bleed your radiators regularly, you will save energy and could greatly improve on the amount you are spending.

  5. Insulate your home
    One of the most effective ways to reduce your carbon footprint and lower your energy bills is by installing insulation or replacing windows and doors with higher rated ones.

How to find the energy rating of a product

All electrical appliances come with an energy rating these days, everything from your fridge to your washing machine. Normally presented as an easy-to-read visual code of coloured bands ranging from red (G or very inefficient) up to green (A++ or very efficient), they are a means of showing how energy efficient the product is. The better the rating, the lower the running costs, meaning more savings for you. The more energy efficient the rating, the better they are for the planet.

Window Energy Ratings Explained

Window Energy Ratings (WER) work in the same way as the energy ratings on electrical appliances. The ratings go from A (very efficient) down to G (very inefficient) and it’s one of the most important elements to factor in when you are considering purchasing new windows. To comply with Scottish building regulations, all new windows installed in homes must be at least C rated.

Calculating WER

To calculate a windows WER, a few values must be considered:

Thermal Transmittance (U value)
This tells us how much heat is lost through the glass and is measured in Kilowatt-hours, per square metre, per year.

Example: 2.5kWh/m2.K means that 2.5 kilowatts of energy will be lost through every square metre of the window, every year. That’s the equivalent of boiling a kettle for every square metre of window!

Solar Factor (G value)
Measured in kilowatt hours per metre, per year, this shows how much energy is gained through the window from the Sun (solar factor).

Air Leakage (L value)
This value measures air leakage through the window. Measured in kilowatt hours per metre, per year, you would want this value to be as low as possible.

So although most new windows may look the same at first glance, it’s very important to research the product's WER rating as they can differ drastically between suppliers. We would always recommend purchasing windows with a WER ‘A’ Rating as standard to help give you peace of mind that your windows are functioning at an optimal level.

How energy efficient windows help reduce heating bills

How to improve your home insulation

Cavity wall insulation

Almost 1/3 of heat lost through an uninsulated house is through the walls. If your home was built after the 1920’s it’s likely you have cavity walls and unless it was built in or around the last 20 years, it’s likely they could be empty. According to the Energy Saving Trust website, installing cavity wall insulation could save you up to £160 a year on your bills and pay for itself in under 5 years.

Solid wall insulation

If your home was built before the 1920s it’s likely your external walls are solid rather than cavity walls. Although more expensive to install than Cavity Wall insulation, the savings on your heating bill would be bigger overall.

New windows & doors

Replacing old windows and doors with 'A' rated ones is a very cost-effective way of heating and cooling both domestic and commercial properties. It will also help you save money on your energy bills and lower your carbon footprint.

The benefits of new uPVC windows

  • Highly Insulated uPVC frames provide a barrier to cut heat loss.

  • Heat from radiators is reflected back into the room.

  • keeping more warmth inside your home.

  • Even during winter, energy from the sun passes through the specialised glass and has a warming effect on the room.

  • They create a more comfortable home with fewer drafts and cold spots.

  • Double Glazing will also insulate your home from external noise.

If installed correctly, ‘A’ rated windows can have a zero-energy loss over a year and even add energy back into the home via solar gain. As an example, a semi detached house with 17m2 of windows and electric heating upgraded from single glazed wooden windows to ‘A’ rated energy efficient casement windows could currently save £1486 a year. This is based on the electric tariff of 34p per kWh in the second half of 2022 and is calculated using the Deceuninck Energy Saving Calculator. Another tip is to add heavy curtains to your windows for use in the winter as this will also help retain the heat.

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Bryant And Cairns Save Money On Your Energy Bills By Removing Old UPVC Double Glazing Bryant And Cairns Save Money On Your Energy Bills By Removing Old UPVC W Indows Extended Details Portrait

How Much Could You Save?

  • Single Glazed Timber Windows 4.8 'U' Value to Double Glazed uPVC 1.4 'U' Value - £935.22
  • Double Glazed Timber Windows 2.8 'U' Value to Double Glazed uPVC 1.4 'U' Value - £379.76
  • Old Double Glazed Aluminium Windows to Double Glazed uPVC 1.4 'U' Value - £1,127.93
  • Old uPVC Double Glazed Windows 2.4 'U' Value to Double Glazed uPVC 1.4 'U' Value - £419.43

All estimates are forecast using the Glass and Glazing Federations Energy Saving Calculator and are based on electricity tariff of 28p per kWh from 2022.

How energy efficient windows help reduce heating bills

Double glazing costs & savings

Double Glazing costs will vary significantly across suppliers, so it is important to obtain a few quotes from reputable installers to ensure your project can be completed within your budget. Remember to ensure that each company is quoting for the same level of product and a start to finish installation service!

For example, Supplier X and Supplier Y should both be quoting for supply of ‘A’ Rated Energy Efficient products. Always be sure to check the fine details, as some may be offering a lower standard of window which would affect the overall price.

uPVC windows tend to be cheaper than traditional timber windows. Although timber windows have a lower initial environmental impact, they will require continual maintenance. uPVC windows are the cheaper option and require no regular maintenance. They can also be recycled if it becomes a requirement to replace them.

Types of windows

Double Glazed units consist of two panes of glass, separated by an air gap, usually around 16mm. This gap is often filled with a gas, such as Argon gas. Argon gas is a poor conductor of heat which is why high-quality double glazing helps keep warm air trapped in your home.

Casement window
The most common form of double-glazed window, the Casement window is hugely versatile. From single opening sashes to multiple openers, it can feature almost any permutation of fixed and opening windows.

Tilt and Turn Window
This clever design means the window can open on different axis, making it suitable for fire escape in upstairs locations and is perfect for when it’s required to be cleaned from inside the building.

Reversible Window
Operating on a rotating hinge mechanism, the entire opening sash can be fully rotated so that the external pane can easily be cleaned from inside. Much like the tilt and turn, this window can be used as a fire escape where required.

Sliding Sash Window
Based on the traditional timber window style, this elegant uPVC option provides all the grandeur of the traditional window type, with the added thermal performance and minimal maintenance requirements that comes from uPVC products.

Product & security guarantees

As part of buying new window and door products, you should always check that the installer offers a suitable customer care and repair service alongside a guarantee on all products. Although uPVC products are hardwearing and have a long-life expectancy, it is still important to ensure that your investment is protected. Any trustworthy double glazing supplier should offer a product and security guarantee with their products, so make sure you check first before proceeding with any purchase.


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