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Will Energy Efficient Windows Pay For Them Selfs?

A rated energy certificateInstalling new, energy efficient windows can help you to save on your yearly energy bills. But, if you’re considering installing new windows, you’re probably wondering how much you can save and if they will really pay themselves off.

If you’ve already done some shopping around, you’ve likely already noticed that buying double glazing isn’t the simple decision it should be. If you want to get a good deal, you have to balance energy efficiency with cost and quality to ensure that your new windows will pay themselves off.

We’ve written a complete guide to buying energy efficient windows in the UK, to help you make the right decisions for your home and your budget.

  • Energy efficient windows can reduce your yearly energy bills as much as £175 per year
  • Triple glazing offers the highest efficiency, but may not balance costs enough to provide a return
  • uPVC windows offer energy efficiency and low cost, but may not add to the value of your home


What Are Energy Efficient Windows


Energy efficient windows help you save money by reducing hot and cold air loss, which reduces the burden on your heating and cooling systems. As a result, you spend less energy heating your home in the winter, dramatically cutting your yearly energy bill. Some energy efficient windows achieve this with quality glass and double glazing, while others use low emissivity coatings (Low E), air or inert gas cushions between panes, or a combination of different methods.

While any window can be ‘energy efficient’ in the context that it is likely more energy efficient than an old window, most retailers use “Energy Efficient Windows’ to refer to glazing with Low E coatings, argon or xenon gas cushions, or an energy rating of A or higher.


How Much Can You Save?


If you’re replacing old windows, you could save a great deal on your energy bills. But how much is a great deal? While the exact rate will vary depending on your home, the age of your current windows, and the size of your house, you can use the following chart as a guideline for how much you can save.

If you’re replacing old C rated windows with new windows, the Energy Savings Trust calculates that you can save the following amounts based on the size of your home.

Energy rating Detached Semi detached Mid terrace Bungalow Flat
A rated £130 – £175 £90 – £120 £80 – £105 £60 – £80 £50 – £65
B rated £120 – £160 £80 – £110 £70 – £95 £50 – £70 £40 – £60

In most cases, the average savings is £120 in savings per year in a detached home, £100 in a semi-detached, £95 in a terrace, £70 in a bungalow, and £60 in a flat. This amount will vary a great deal depending on your house and your existing windows.


How Much do Energy Efficient Windows Cost?


While you can save as much as £175 per year with energy efficient windows, it’s important to know how much they cost so you can calculate actual savings. The average uPVC window costs between £300 and £400, but if you’re looking for a quality, A rated or higher window, you should expect to pay more.

The following include average costs for energy efficient windows with Argon gas, low-E coatings, or other similar energy efficient measures.

Material   Cost  
UPVC £350-570
Composite   £575-625
Wood   £845 – £1,500+


How much does that cost? Assuming you choose a budget uPVC frame, you can expect the following costs and savings averages over 25 years. *

Energy rating Detached Semi detached Mid terrace Bungalow Flat
Savings per Year £130 – £175 £90 – £120 £80 – £105 £60 – £80 £50 – £65
Average Cost to Install £3,500 £2,800 £2,100 £1,750 £1400
Savings over 25 Years £4,375 £3,000 £2,625 £2,000 £1,625
Return £875 £200 £525 £250 £125


*Detached calculated at 10 windows, semi-detached at 8, Mid-terrace at 6, bungalow at 5, and flat at 4. Your costs will likely be lower, as the average home in the UK sports 8 windows.

In fact, total average costs vary between £2,500 and £3,500. However, if you have a bigger home, you will pay more. A 5-bedroom detached home with 15 windows will cost £5,250 or more to replace windows, however, you will earn back a higher return, as you will save more than the calculated savings which are based on 2-3 bedroom homes.

Now that you know what you can save and how much it will likely cost, you probably want to know how to pick the right energy efficient windows.


What Affects Energy Efficiency


Energy efficiency is rated and listed using multiple ratings. These can be confusing, but understanding them allows you to choose higher efficiency windows for your house.

G-Value (Solar Gain)

Solar Gain or “G-Value” refers to the increase in temperature from light radiation. A window with a low G-Value will stop heat transference, so that your home does not heat up with the sun on the glass. Some windows feature a G-Value of 0.0%, which means that no heat is transmitted. However, while valuable in the summer, this feature deprives you of free heat in the winter, so there is a trade off.


U-value or U-factor measures heat loss or thermal efficiency. An energy efficient window will have a U value of 40 or lower. Double glazing can achieve a U value of 30, while triple glazing can achieve a U value of 15.


R Value refers to the insulative properties of the windows. However, it is typically used synonymously with U-Value.

Energy Rating

The Window Energy Rating (WER) is listed as A through E, and calculates the energy efficiency of the window. British law states that you can only purchase windows with a C rating or higher. WER takes every factor into account, and it is the most important thing to pay attention to.


Different types of glass, glazing standards, and glazing thickness affect your energy efficiency. Double glazing typically offers the highest return on value, because it offers high energy efficiency with lower cost than triple glazing.

Coatings (Low E)

Some windows feature coatings like Low E or Low Emissivity coatings. A coating helps to protect your window, may add UV protection, and may otherwise improve the energy efficiency of the window.


Wood, composite, and uPVC frames offer the best energy efficiency. Aluminum frames conduct heat, which makes them inefficient for reducing energy usage.

Air Cushion

Some windows feature an air cushion, or an inert gas cushion. Inert gas barriers such as argon, krypton, or xenon are denser than air, making them more suitable for stopping airflow through the window, which can dramatically improve efficiency.

Now that you know what to look for, you probably want to know what’s important for your home, and what fits into your budget.


Balancing Cost and Budget to Ensure a Return


While some windows can offer very high efficiency, it is important to pay attention to costs vs your potential return so that you can get a good deal and save over the long term.

UPVC vs Wood & Timber – uPVC frames are often as much as half the cost of wood or timber (and sometimes less). They are also energy efficient, easy to care for, and last for 10-25 years depending on the quality, size, conditions, and care. However, if you plan to sell your home, wood or timber frames will add more value. If your largest concern is choosing affordable windows, uPVC makes the best choice.

Double vs. Triple Glazing – While triple glazing can increase the performance of your windows, this increase doesn’t yet offset the costs of installation. If your goal is to reduce energy consumption to reduce your total carbon footprint, triple glazing is an excellent choice that will greatly improve the energy efficiency of your home. Double glazing allows you to reach parity with costs, so that you break even or earn a return over the lifetime of the window.

Xenon, Air, Krypton, Argon, etc. – Gas filled units offer higher efficiency, but it is important to pay attention to the gas and the warranty. For example, Krypton gas offers higher efficiency than Argon, but does not typically offset the added expense of the gas. Argon gas usually offers the best ‘bang for your buck’ in that it is cost effective and improves efficiency.


Getting a Good Deal on Energy Efficient Windows


If you’re installing new windows, you need to know that they will pay themselves off. This means paying attention to your windows, installing quality windows with high energy efficiency, and getting a good deal on the installation.

You should know what you want, why, and how much it should cost before you call an installer or salesperson. If you know what you’re looking for when installers visit your home, you can avoid paying more for something you don’t want or need.

If you’re ready to install new, energy efficient windows, we can help to ensure that you’re getting the best deal. Use our free comparison tool to find and compare the top local installers in your area and save as much as 37.5% on your glazing.


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