Energy Efficient Windows - Checklist Before You Buy
As we bid farewell to summer and welcome spring, you may have started to detect a drop in warmth at home and your windows could be the problem.
Energy efficient windows are what’s required to keep more heat in over the winter and see that your property doesn’t overheat in summer. Their design incorporates contemporary glazing, insulating frames and airtight seals, which combine to stem heat loss more effectively than old single glazing or the most basic double glazed windows.
They can also fight off condensation and restrict noise transmission. There’s no getting away from the fact that energy saving windows will command a noted investment, but you can earn much of that money back through lower energy bills.
- By how much can energy efficient windows cut UK heating bills?
Heat loss can be reduced by up to 70% when you exchange old single glazing or substandard double glazing for A-rated energy efficient windows. The average semi-detached UK home can achieve an annual saving of roughly £100-300 on heating costs. Bigger savings are possible if you reside in a detached or expansive home because of their larger window surface areas and escalated energy usage. Things like U-values, airtightness, current insulation and the property type equally influence the amount saved. - Would I be better off with double or triple glazing?
Triple glazed windows are undoubtedly worth considering, but modern double glazing is more than sufficient in the UK, providing first-class thermal efficiency at an affordable price. It manages this feat in just about any location and whatever the orientation of a house happens to be. - Is UPVC, aluminium or timber the most energy efficient material?
UPVC windows are multi-chambered and supply fantastic insulation, aluminium is more expensive but contains thermal breaks, while timber insulates naturally but requires a lot of maintenance. Window performance relies on the choice of frame, its opening style, sealing, longevity, cost and the sightlines offered. A conversation with one of ERG’s advisors will help you clarify what window is the best to buy according to your home and budget. - What BFRC rating and U-value do you recommend?
A window’s U-value (W/m²K) indicates how effectively it stops heat transfer (aim for a low U-value) and a BFRC Window Energy Rating (A++ to C) denotes overall energy efficiency. More about U-values can be found in our article about what is a good u value for windows. Pursue whole-window Uw and WER targets for UK residences and weigh up equivalent specifications when shopping for energy saving windows.
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Getting to know insulated windows (heat loss & solar gain)
Through the processes of conduction, convection and radiation, insulated windows slow heat loss. Heat gets reflected back inside thanks to the Low-E coatings, with gas fills reducing conductive losses and warm-edge spacers minimising heat escapes at window edges.
These united constituents deliver high-ranking thermal performance, decrease energy bills, control solar gain and attract and retain sunlight.
Explaining Low-E glass and how it uplifts energy efficiency
There’s a minute metallic coating in Low-e glass that reflects heat back into the house and enables light to enter.
In the simplest terms, it means that it stops warmth escaping in winter and lessens the risk of overheating in summer, resulting in increased comfort and energy savings.
Older window units don’t have Low-E coatings, which is why their energy efficiency is significantly inferior.
Gas fills & spacers (argon/xenon/krypton, warm-edge technology)
Heat transfer between glass panes is reduced by gas fills such as argon, xenon and krypton, with warm-edge spacers cutting thermal bridging at the frame.
Additionally, they reduce the possibility of condensation, magnify U-values and preserve the indoor temperature at a steady level.
Upgrades of this type will only elevate thermal efficiency and overall day-to-day comfort.
Are UPVC, Aluminium or Timber frames most energy efficient?
UPVC window frames insulate impressively, need very little care and can last a lifetime. Aluminium features thermal breaks and is incredibly robust as well as remarkably slim. Timber is the most natural insulator, but it is costlier to maintain, and its energy efficiency can diminish once the frames start to weaken.
Issues of thermal performance, longevity, sightlines, aesthetics and thermal efficiency are affected by frame choice and the glazing used.
Casement, sash or tilt & turn – which style is most efficient?
The raft of window styles manage to attain differing standards of energy efficiency in keeping with how they’re sealed. Initiate a discussion about draught proofing windows and the best energy efficient windows for containing heat in the home.
Casements and tilt and turn windows tightly close, restricting draughts and heat loss, whereas traditional sash windows can be prone to leaking more air.
Windows with thorough sealing that realise high performance will stop heating bills getting out of hand and raise home comfort.
How the window rating systems work (BFRC, WER & U-values)
A window’s energy performance is measured by the BFRC Window Energy Ratings scheme in the UK, from A++ to C, highlighting how efficient it is. U-values symbolise how much heat gets out of a window, with a low number being the best option.
There is a relation between WER and U-values, but the former relates to glazing, frame and sealing, while the latter focuses on heat transfer.
Doing a comparison of the two will put you in the direction of quality performing windows.
Clarifying window energy ratings and the BFRC rating system
A Window Energy Rating (WER) indicates the energy efficiency of replacement windows in Scotland, considering their frames, glazing and seals. The best rating is A++, making it easy to identify window performance from one window to the next.
The importance of U-values and understanding them
A U-value indicates how much heat escapes through a window (the lower the number, the better the insulation). Uw = whole window value, Ug = centre-pane glass only. Typical ranges:
- Single glazing: 5.0–6.0 W/m²K
- Old double glazing: 2.8–3.0 W/m²K
- Modern A-rated windows: 1.2–1.6 W/m²K. Concentrating on Uw will confirm genuine thermal performance.
How A, B and C-rated windows differ
Energy efficiency varies between A, B and C-rated windows, a motivation for establishing the Window Energy Rating (WER) system. A-rated windows come out top for thermal efficiency, heat retention and minimising energy consumption, with C-rated windows being a minimum requirement to meet building regulations and the cheapest of the trio.
A+ to G is the scale for the Window Energy Rating (WER) system, the most energy efficient being A+. An upgrade from C-rated windows to A-rated windows can significantly improve home comfort, reduce draughts, warm up rooms and cut costs.
Double Glazing vs Triple Glazing – which is best for UK homes?
Modern double glazing more than suffices for most UK properties as it gives a perfect balance of energy efficiency, comfort and cost. Where triple glazing has a slight advantage is for homes in extremely cold climates or that are north facing. It’s also good for restricting noise, but its costlier and weighs heavier.
There isn’t a right or wrong choice, it’s just a case of recognising which suits your home and goals most, and rarely does our double glazing not do the job!
Closing thoughts on high performance thermally efficient windows
Knowledge of window ratings and specifications will guide you to the most befitting insulated windows. If it seems too much of a burden, ERG is here to help you uncover whether to go for double or triple glazing and give advice on frame materials to achieve the desired energy efficiency.
Contemplate what the potential returns are when deciding what to pay, organise a professional installation and prioritise accredited installers, just like ERG Scotland.
Lean on our experts for anything to do with locating an appropriate window material and style that will drive down your energy bills and take the heat off your boiler system.
Strike gold with your window buying and cheaper energy and amplified comfort is a certainty, plus you won’t have to change your windows again for many years.
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