Coloured wooden windows

What U-Value Should Windows Have?

When you’re shopping for a new set of windows, there’s one metric that you’re almost certain to encounter, and that’s the ‘U’ value. This number is a way of describing a window’s thermal efficiency, but what does it mean? What are the best U-value windows, and what’s the U-value of double glazing?

How Does U-Value Work?

Let’s start with some definitions. A U-value is a measure of heat energy moved through a given area of material in a given period of time. This might be a window, but it might equally be a wall or a door. It’s most often measured in watts per metres squared, when the difference in temperature between the two sides is one-degree Kelvin. Given that that’s a bit of a mouthful, we tend to say ‘W/m2K’ instead.

It’s important to note here that the U-value of a given window refers to its efficiency per square metre. So, two windows might have the same U-Value, but transmit heat at different rates because one is a different size to the other.

The lower its U-value, the better an insulator the window will be. If you’re aiming for the most thermally efficient house possible (as most of us are, cost permitting), you should almost always go for the window of the lowest U-value.

How Do You Calculate the U-Value of a Window?

If you’re buying a new window, you’ll be able to see its U-value advertised by the manufacturer. Unfortunately, calculating a window’s U-value yourself isn’t particularly easy, nor are your calculations likely to be totally accurate. However, if you’re determined to try and calculate the U-value of a window yourself, you can find out how here.

For example, not every glass panel is manufactured to the exact same standards, and what stacks up in a laboratory might not translate into the real world. While there are bodies like the BFRC (which we’ll discuss in a minute) there to maintain quality standards, it’s important to treat claims about efficiency with a degree of scepticism.

Secondly, the glass panel isn’t the only thing you need to consider – the window frame also conducts heat, and will contribute to the thermal efficiency of the window. While it’s possible to account for this in your calculation, given that the interior of a window frame is made from a range of different materials, doing so can be very difficult.

To comply with building regulations, windows (like every other element of your property) must meet a certain minimum U-value. In the case of a window, it’s 1.6 W/m2K. Double-glazed windows, filled with argon, are typically 1.4 W/m2K, while thicker triple-glazed windows can go as low as 0.7 W/m2K.

The British Fenestration Rating Council provide a colour-coded rating system to help homeowners distinguish between different qualities of window. Good windows which keep the heat in are rated A or above. Bad ones are related E or below. While this rating system is easy to follow, and will prevent buyers from making a mistake they’ll regret for years, it isn’t quite as specific as the U-value. As such, when you’re shopping, we’d suggest looking for the U-value and spending your money accordingly.

For example, Jeld Wen’s triple-glazed ‘Stormsure Energy+’ series of casement windows can have a U-value of 0.8, 0.9 or 1.0, depending on which options you select. Each window in the range, however, comes with the same BFRC rating of A+. So, if you want the absolute maximum thermal performance available, you’ll need to look beyond the lettered rating, and at the U-value.

U-Value: Double Glazing versus Triple Glazing

Given how effective double-glazing is compared to single-paned glass, you might suspect that adding an extra layer would improve things still further – and you’d be right. Triple-glazed windows are more effective insulators than their double-glazed counterparts.

That said, there are a few drawbacks to consider. Triple-glazed windows tend to be thicker, which means they’re not ideal for use in smaller frames. They’re also more difficult to manufacture, and as a result, more expensive.

Putting to one side practical considerations like these, there are a few instances where a triple-glazed window might not be as good a choice as its U-value might suggest. This is because of heat gain, or a lack of it.

As sunlight pours down onto your triple-glazed window, the heat won’t reach the interior as quickly as it might if the window were double-glazed. As such, south-facing windows which receive direct sunlight might be better suited to double-glazing than triple-glazing.

In Nordic countries where triple-glazing is widespread, there’s less sunlight, and so this issue isn’t as pressing. In the UK, it’s worth treating triple-glazing with a bit more caution. We’ve examined the thorny double-versus-triple-glazing debate in greater depth in a previous article, and if you’re considering going for triple-glazing, we’d suggest that you give it a read.

While U-value isn’t the only metric of a good window, it’s one worth paying attention to before you make your purchase. Generally speaking, the lower the U-value, the better. It’s worth investing more in a superior-quality window, as the extra cost is likely to pay for itself over the lifetime of the glazing. That said, thermal efficiency isn’t everything – if you’re not happy with the look of the window, or the warranty isn’t sufficiently long, then going for a super-efficient U-rating at all costs probably isn’t a sensible strategy.

Ready to shop for new windows? Get an estimated quote here.

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Wintery street

How to Winter-Proof Your Windows

If, like most of us, you want to reduce your heating bills, you’ll need to pay close attention to your windows – largely because they lose heat much faster than the surrounding walls. This, as you might imagine, is especially important when temperatures drop, so it’s worth thinking about before winter arrives.

What are the Most Winter-Proof Window Designs?

Let’s look at a few popular varieties of window, and how effective they are at retaining heat.

Casement Windows

A casement window operates via a hinge, and usually opens outwards. This makes it compatible with draught-reducing silicon seals, which run around the edges of the window and are compressed when the window is closed. These seals will degrade over time, gradually losing their elasticity, and so must be replaced every so often.

Sash Windows

By contrast, a sash window moves up and down (or from side to side) within the frame. In place of soft seals (which would create friction and prevent the window from moving), sash windows feature draught-excluding brushes.

Like the seals in casement windows, these brushes will wear away over time, and so should ideally be replaced every few years.

Older Windows

If you’re the owner of an older property in a conservation area, the changes you can make to your home will be limited. This is because your planning officer will want any replacement windows to conform with your existing windows.

houses in a UK village

In fact, it can sometimes be tricky to get double-glazing installed in older properties. Firstly, the difference in pressure between the interior and exterior of a double-glazed window can produce a noticeable bowing effect on the glass. Then there’s the fact that double-glazing for period properties tends to cost considerably more than typical double-glazed windows.

That’s not to say that owners of older properties are out of luck – there are plenty of new windows which work well in older properties.

Bay Windows

Bay windows, technically speaking, aren’t windows.

They’re groups of several windows, arranged together. As such, bay windows can either be casement or sash. Given that bay window protrude slightly from the building, they’re a little more vulnerable to cold spells than most other types of window.

This means you’ll want to dress the windows properly and ensure they’re thoroughly maintained.

Arched Head Windows

Arched head windows feature an arch at the top for added visual interest. The top of the arch is usually sealed into place, with the bottom of the window functioning like a traditional sash window.

What is Best for Winter: Double or Triple Glazing?

Argon-filled double glazing is the gold standard for modern windows, but there are ways to make the technology even more efficient. You could choose windows with a denser gas, like krypton or xenon – but that’s often overkill, especially since they cost considerably more than argon-filled windows.

Another option is to increase the depth of the cavity, but this would result in an incredibly thick window, and exacerbate the bowing effect we’ve already discussed. What’s more, a cavity that’s too thick can create convection currents, via which heat can be transmitted from one panel to the other.

In Scandinavia and other particularly-cold parts of the world, a popular solution is triple-glazing. Triple-glazing is formed of, as you might have guessed, three panels of glass rather than two.

houses in Svalbard

Triple-glazed windows are trickier to manufacture than double-glazed windows, so they understandably cost more. They also reduce the amount of light entering the property’s interior, and how much heat is gained through sunlight exposure. As such, if your window is south-facing, you might end up reducing the energy efficiency of your property by installing triple-glazing.

We should bear in mind that winter is relatively short in the UK, so the added expense incurred by triple-glazing should be offset against the light-reducing effect it has for the rest of the year. For most of us, there are many energy-saving measures worth considering before triple-glazing is worth the expense.

Window Ratings Explained

If you’re comparing different windows, you’ll have probably encountered all sorts of arcane terminology. To confuse matters further, British and American manufacturers use different rating systems.


The u-factor (or u-rating) measures the rate at which heat flows from one side of a window to the other. The lower the number, the more efficient the window.

U-rating is usually determined using the centre of the glass, which means the effect of the frame is discounted. You should expect a good double-glazed window to achieve a u-rating of around 0.3. U-factor is related to R-value, which is more commonly used to calculate the efficiency of solid brickwork.

Solar Heat Gains Coefficient (SHGC)

Whenever sunlight hits your window, some of it will pass through, leaving the remainder to bounce away. In doing so, this portion will help heat your property. The higher a window’s SHGC, the more heat it gains through solar energy. In winter, this extra heat will make a difference to both your comfort, and to your energy expenditure.

Visual Transmittance (VT)

This works just like the SHGC, except instead of measuring the proportion of heat energy entering the building, we’re measuring the amount of visible light. The two don’t always correlate, as manufacturers add special coatings that filter out certain wavelengths.

Air Leakage (AL)

Air leakage measures the volume of air that can circulate through a window in a given timeframe. The lower the AL rating, the draughtier the window. In many cases, a little circulation is required to allow the building to ‘breathe’ and thereby prevent damp.

British Fenestration Rating Council (BFRC)

The BFRC are the central body responsible for upholding window standards in the UK. They issue licences to approved manufacturers, and stipulate which retailers are authorised to sell approved windows. To make things a little less confusing for the customer, each window approved by the BFRC comes is rated between E and A++. This rating combines all the measurements we’ve described into a simple grade, so it’s easy to make rough comparisons between different windows.

How to Insulate Your Windows for the Winter

Whatever windows you’ve chosen, there are several steps you might take to increase their heat-retaining abilities for the season.

Heavy dressing

Heavy curtains can reduce heat lost through the windows by preventing the cold air around the glass from mixing with the warm air in the room. To get the best from this, you’ll need to actually draw your curtains at night-time.

Secondary Glazing

Secondary glazing works a little like double-glazing, except instead of two glass panels built into the same unit, a second panel is fitted to the inside of the existing window. Since there’s no pressure difference, there’s no bowing effect. What’s more, you can remove the secondary glazing when the weather gets warmer.

You can also get flexible and rigid plastic secondary glazing, called winter window clings, which can be fitted to the window frame for winter.


As windows age, the seals which run around the edges wear out – i.e. the stuff that runs around the edge of the frame, and the brushes and rubber strips that sit on the frame’s inside. Make a habit of inspecting these every year, and replace them when necessary.

Draught Excluders

These are long, tubular cushions, often crammed underneath leaky doors. If your windows are draughty, they can serve the same purpose.

Low-e glass

Low-emissivity glass is glazing that’s coated with a very thin layer of reflective metal, that helps prevent heat escaping. Most modern windows are low-emissivity.

Need new windows? Browse our sliding sash or casement windows or find out about our handmade bespoke windows.

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wooden windows

Argon vs. Krypton vs. Xenon in Windows

When it comes to energy efficiency, windows are notoriously vulnerable.  Given a chance, they’ll drain the heat out of your home and into the great outdoors, far faster than brickwork and doors.

Of course, this isn’t a new problem, but in recent years better solutions have entered the market.  Of these, double-glazing is the best-known.  In a double-glazed window, two glass panels are placed parallel with one another, with a layer of insulating gas sandwiched in-between.

The precise makeup of this gas has changed over the years.  When the technology first appeared in Victorian Scotland, manufacturers used ordinary air.  During the middle of the 20th century, manufacturing techniques became more sophisticated, and the air was replaced with a vacuum.  Inside a modern double-glazed window, however, you’re likely to find one of three noble gases: namely argon, krypton or xenon.  Take a look at the periodic table, and you’ll find them stacked on the right-hand side.

But what are the practical differences between these gases?  Why is argon used in double glazing instead of air?

Why Argon in Windows?

Argon gas windows represent, in most situations, the optimal balance between performance and cost.  If you shop for double-glazed windows, you’ll tend to find that they feature argon alongside low-emissivity glass, and thereby drop heat gain during summer while keeping the interior cosy during winter.

Argon offers a thermal conductivity around a third lower than ordinary air, for only a marginal increase in cost.  Treated well, argon-filled double-glazing will last for more than two decades, losing only a fraction of its performance over the years.

Are Argon Filled Windows Worth It?

In most cases, argon-filled windows are an obvious choice.  Having said that, some circumstances might call for a more expensive, high-performance gas.

Why Krypton in Windows?

Krypton represents something of a middle-ground between argon and xenon.  It’s more expensive than the former, but less so than the latter.  It’s yet to overtake argon as the industry standard, on account of its higher price, but this might well change in the future, should manufacturing techniques become even more sophisticated.

Krypton-filled double-glazing tends to be thin.  Indeed, if krypton is used in a wider gap than, say, 20mm, convection currents will begin to form that transfer heat from the interior of the window to the exterior.

In old buildings, cavities were filled with single-paned windows, meaning there might not be sufficient room for a thicker argon-filled window.  You might therefore consider krypton-insulated windows as a means of preserving the aesthetic of the building while enhancing the insulation.  It’s worth considering the potential difficulties inherent in obtaining planning permission for a double-glazed window in a period property, since the difference in pressure between the two sides will generate a bowing effect on the glass.  This can undermine the appearance of the property from the outside.  That said, this drawback is common to every sort of double-glazing – not just krypton-filled windows.

If you don’t have any such space-restrictions to worry about, then you might cram multiple layers of krypton gas into the same window.  Triple-glazed krypton-insulated windows incorporate three panes of glass, the middle of which will interrupt the convection currents we’ve just discussed.  In the UK, such windows are installed only rarely, since temperatures don’t often dip low enough to justify them.  If you’d like to go down this route, however, krypton is worth considering.

Are Krypton-Filled Windows Worth It?

It’s difficult to state with certainty whether krypton-filled windows justify their price-point, as the answer will depend on your aims.  Most in the building industry will view them as an extravagance, but if you consider energy efficiency to be important, krypton might well prove tempting.

Why Xenon in Windows?

Let’s take a moment to consider trends in the world of architecture.  A modern skyscraper has a surface area made almost entirely from glass, and they’re not an exception – courthouses, swimming baths, service stations and office buildings across the country are increasingly transparent.  The advantages of this approach are obvious: glass allows more natural light into an interior, and helps us to see the world outside.

But how can architects incorporate such large expanses of glass without compromising the energy efficiency of the building?  One answer comes in the form of xenon.  Xenon-filled windows are a relatively recent innovation, and sit at the forefront of glazing technology.  They’ll insulate wonderfully.  But this performance comes with a price tag to match.

Xenon gas windows are therefore permitted in exceptional circumstances only.  If a business wants to achieve LEED certification for their headquarters, for example, then xenon might just be a way to do it.  Some residential circumstances might also warrant the use of xenon-filled double-glazing – but these are rare.

Are Xenon-Filled Windows Worth It?

The short answer is: probably not.  Xenon’s eye-watering price puts it out of reach of all but the most ambitious homeowners.  That said, if you’re planning your dream property, and you’d like to incorporate a lot of glass, then the performance of xenon might make it worth considering.

So What Should You Choose for Your Windows:  Argon, Krypton or Xenon?

When it comes to energy efficiency in double-glazed windows, the three gases could accurately be labelled as ‘Good, Better and Best’.  A denser gas will perform better as an insulator, but this performance comes at a cost.

Your choice of window will, to a large extent, depend on your personal tastes and circumstances.  For most of us, the insulating qualities of argon will be more than sufficient, and the cost of the more effective materials will outweigh their advantages.

Looking for new windows for your home? Browse our sliding sash or conservation windows or find out about our handmade bespoke windows.

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20 Ways You’re Wasting Energy

Homes today are more energy-efficient than they’ve ever been. They’re also filled with more energy-draining items than ever before. You might not think much about leaving the fridge open while you make a sandwich, or spending an extra five minutes in the shower, but together, the energy you’re wasting really adds up.

What Wastes the Most Energy?

1.      Overboiling

Let’s kick off with a classic – boiling more water than you need to.  If you’re boiling a litre of water every day to provide one 200ml cup of tea, then you’re boiling 292 litres more water than you need to each year.  That’s enough to fill around four bathtubs.  If you’re boiling water on a gas hob, then you’ll save yourself money – just be sure to switch it off as soon as it comes to temperature!

2.      Fridge Doors

Leaving the fridge door open longer than necessary is another common way we waste energy. It might not seem like a big deal to leave it open while you get a bowl of cereal or make a sandwich but for every second that door’s open, your fridge is forced to work harder (and is wasting energy unnecessarily while it’s at it).

3.      Overusing the oven

The microwave is far more efficient for reheating food than your oven.  When you are using your oven, avoid opening the door to check how your food’s doing – ovens lose heat fast and have to use more energy to get back to temperature.

4.      Gaps

Tiny gaps around the edges of your doors, or between the bottom of your curtains and windowsill, will contribute to energy wastage.  During winter, you can correct these problems with the help of a draught excluder or a pile of towels. Alternatively, try sealing gaps (or investing in new windows or doors).

5.      Washing too hot

Most laundry will wash just as well at 30°C as it will at 40°C.  This will also extend the lifespan of your clothes. Separate your washes so that the most severe stains can be dealt with at higher temperatures.

6.      Washing too light

The more clothes you can wash simultaneously, the fewer loads you’ll have to do and the less you’ll have to spend on washing.  Of course, there’s an upper limit to this wisdom – you’ll need to provide the water with space to drain properly, and the clothes with space to move around.

7.      Underloading the dishwasher

The same logic applies to the dishwasher – except you don’t really need to worry about overfilling a dishwasher.  Fill your dishwasher to capacity and use the most efficient setting.  You can use the money you save to invest in more crockery and cutlery!

8.      Drying

Drying your clothes naturally by hanging them on clothes horses, or out in the garden on the line, will save a considerable amount of money relative to a using a tumble-dryer.  Your choice of dryer will also impact the money you spend.  Which? suggest that a C-rated dryer costs around 49p per load, compared to just 14p for an A-rated one.

9.      Bathing

Baths are expensive – period.  Replace just one bath a week with a five-minute shower and you could save about £40 a year on your water and heating bills.

10.  Long Showers

A long shower might relax you, but the cost won’t. Just 8 minutes under an electric shower costs between 20 and 30p. Double that time, and double it again for a 2 person household, and you’re looking at up to £1.20 a day – or £438 a year!

11.  Inefficient showers

Modern showerheads are able to create the illusion that they’re using more water than they actually are.  If you can, adjust your showerhead to provide a pressurised blast of not-very-much-water.

12.  Not switching things off

If you’re leaving a room and no-one’s in it, turn off the lights.  Simple.

13.  Light bulbs

Traditional halogen bulbs are on the way out.  Modern LED bulbs are many, many times more efficient – and the gap is certain to keep growing.   In fact, the rate of improvement is sufficient that stockpiling spare bulbs is inadvisable!

14.  Not turning the TV off

Many of us like to cap off a week by unwinding on the sofa with a glass or two of wine and a marathon of television.  You’re not going to get much enjoyment from your favourite shows, however, after you’ve fallen asleep – so be sure to switch off and go to bed before you crash out.

15.  Leaving the tap running

This is totally unnecessary.  The average tap can dispense six litres of water in a minute, which adds up to more than eight thousand litres per person brushing their teeth every year.  Just turn it off!

16.  Ignoring a leaky tap

That drip-drip-drip might not seem worth worrying about but as we’ve seen, small amounts of wastage can add up.  That tap’s going to be leaking 24 hours a day.  Get it fixed.

17.  Not programming your thermostat

If you’ve invested in a programmable thermostat, then you’ll want to do some actual programming.  It’s incredibly easy, and it could save you around £70 a year.  That way you can be sure you’re not wasting energy when you’re not home.

18.  Leaving your hot water cylinder exposed

Insulating this contraption will save around £20 a year – and perhaps more.  The improvement takes seconds, and you’ll only need to do it once!

19.  Keeping an old boiler

Old boilers tend to be massively inefficient.  Since heating represents around 60% of the average household’s costs, upgrading to a modern A-rated boiler can make a substantial difference!

20. Not using stacked steamers

If you’re going to be cooking broccoli, asparagus, potatoes and carrots, is there really any need to boil four separate pans?  Of course not – invest in a set of stacked steamers, place the lid on the top, and cook four things using the same energy it takes to heat a single pan.

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How Much Do Curtains Help with Heat Retention?

If you’re looking to save money on your energy bills, then you should view your windows as a priority.  A significant amount of heat is lost through a home’s windows, but there’s an easy way to reduce that loss – curtains.

Why do curtains help with heat retention?

Curtains help with heat retention by limiting the flow of air between the warm and cold areas of a room.  Even double-glazed windows will afford heat with a chance to escape, but a set of heavy curtains will form a barrier that’ll limit the flow of air from the main room to the window.

While some air particles will be able to move through the gaps in a curtain, many of them will encounter resistance – just like wind blowing against a ship’s sail.

Even if the air immediately beside the window cools considerably, if it doesn’t have the opportunity to mix with the warm air in the rest of the room, you won’t notice – and neither will your energy bills.

What about letting sunlight in?

Of course, if we’re concerned about energy efficiency, then we shouldn’t just be concerned with heat escaping the room; we should also worry about the sunlight that might find its way in.  Heat from outside your property can limit the strain on your energy bills.  It’s of particular concern if the window in question is south-facing, as there will be more direct sunlight to allow into the house.  As a rule, you should open up your curtains as soon as the light strikes them for best effect.

What sort of curtains are most effective for heat retention?

According to researchers from the University of Salford, drawing your curtains at dusk can reduce heat loss by around 15-17%.   With blinds, the figure is a little lower at 13-14%, but the difference is enough to make closing them worth it.  These findings have been echoed in laboratories across the world, with the US department of energy putting the figure at around 10%. This can go up to 25% if you’d like to seal your curtains to your wall on either side with electrical tape.  While this might seem like an extreme measure, it’s one that might be worth considering in areas where the rear of the curtains is unlikely to be visible.

How much heat can curtains help retain?

By extension, heavier curtains are better at preventing heat exchange between the cold air around the window and the warm air in the rest of the room.  The thicker the curtains, generally speaking, the more effective they are as an insulator.  The best insulating curtains come with a lining attached to the rear, which is designed to limit airflow and noise transfer.  You might even consider a second pair of curtains, designed for exactly this purpose, which hang just behind the first pair.

Hand opening blinds on window

How to Maximise Natural Light in Your Home

It’s a glorious day outside but you have one room in your house that just seems to remain dull and dark. It’s a common problem encountered by many, but how do you draw more natural light into your home?

Getting natural light into a dark room is important. It not only helps you see things more clearly; it offers lots of health benefits too. Natural light boosts your mood and is known to release endorphins, meaning a light and airy room will make you feel happier and more energetic.

Getting as much light into a room as possible is also good for your house. The heat from the sun can reduce condensation and damp and help warm it up, reducing how much you need to use the central heatingy. Sunlight is also known to reduce the production of bacteria and other critters that may want to set up camp in your house.

What can be done to utilise and maximise natural light?

Choose your colours wisely

Even if you only have a small window or a north-facing room, the colours you choose for it can have a massive impact on just how it reacts with the light. Reflective, neutral colours such as white, magnolia and cream will instantly brighten a room; the same goes for the colour of your ceiling. Avoid using darker colours here as this will instantly absorb the light and make the room seem smaller. Using bright neutral colours also make a great blank canvas for your decor choices.

Include mirrors

Mirrors and other reflective decor such as glass pendant lights and chrome ornaments can help move the light around the room. A mirror placed directly opposite the source of light, whether it be a window or door, will instantly create the illusion of another light source=. If it’s a kitchen that you’d like to brighten, consider light coloured work surfaces and reflective additions such as glass splashbacks.

Avoid over dressing your windows

The worst thing you can do when it comes to a source of natural light is cover it up. A common thing to do with a light coloured room is to have dark accessories; this often includes blinds and curtains. Unfortunately fitting dark curtains and blinds to a small window will dramatically reduce the amount of light that gets through to your room. Instead, opt for a lighter colour and give yourself the option to open the dressings fully. Sheer curtains are also a good option as they let the light through and into the room without much adjustment.

Consider the layout of your room

To maximise light distribution throughout a room, avoid placing large furniture near the window. If it’s a bedroom that needs more light, furniture such as wardrobes should be kept to a different area of the room.If they can effectively “box in” a window, they will cast shadows in other parts of the room.

Keep your windows clean

This may seem really obvious but it really does make a difference. Dirt and grime build up on windows is an inevitable problem and can reduce the amount of light getting through into the room if allowed to build up. We would recommend giving your windows a good clean every couple of weeks.

Add windows

This is an extreme option, but worth it if your property is suitable and you have the funds for the work.

If you’d prefer not to add a window due to the cost or change of aesthetics, there are other options available. Tubular skylights go up through the ceiling and out through the roof. Sunlight then reflects down into the room providing another source of natural light. These are however only really suitable in upstairs rooms or bungalows.

Windows could also be installed internally to draw light from other areas of the house, if this is preferred.

Trim back any trees and foliage outside

It’s not uncommon for trees to cast a shadow and reduce the amount of light that can enter a home. Cut back any trees that may be causing problems and trim back any climbers that may have started to trail up the window.

Choose the right colour flooring

Much like walls and ceilings, floor colour can have a huge impact in how light is distributed around a room. Dark floors and carpets can draw down the light and take it away from the rest of the room. Lighter carpets and flooring will spread the light a little further across the room. If you’re extra courageous, polished floors are especially good for light distribution.

Let there be light!

Not everyone is blessed with a house where every room is south facing and benefits from a whole day of sunshine; because of that there are many things that can be done to help. Follow our tips and you’ll be basking in glorious sunshine in no time!

wind turbines

How to Make Old Windows Energy Efficient Without Replacing Them

If you want to make energy savings at home, it makes sense to look at installing double glazed windows.

Double glazed windows work by placing two sheets of glass parallel to one another within the same window.  The space between the panes is either filled with dehydrated air, a vacuum, or an inert gas like argon.  This serves to considerably improve a window’s thermal performance, thus saving homeowners hundreds – and sometimes thousands – of pounds over the lifetime of the window.


There are some cases, however, where installing a new window simply isn’t feasible.  Replacements carry an up-front cost that future energy savings will justify only after many years.  Moreover, in some conservation areas it will be difficult to obtain planning permission for a double-glazing installation.

So what are the alternatives?  How can we prevent heat from escaping our property without replacing our windows?  Let’s examine some potential solutions.

Secondary Glazing

If double glazing isn’t a viable option, then you might instead consider secondary glazing.  This involves placing a second sheet of glass on the interior of your window, which helps to contain heat in much the same way that double-glazing does.  Since the air between the glass isn’t sealed, there are no differences in pressure to worry about.  If your windows boast a classic, period look, then you’ll be able to keep them looking exactly as they currently do from the outside – while at the same time achieving a considerable improvement in thermal efficiency.

Secondary glazing inserts are usually held into place via a compression tube, which sits around the edge of the window, and holds the panel into place via suction.  This means that you needn’t make any modifications to the window.  Inserts are often made from acrylic rather than glass, and will thus contain the warmth of your interior all the more effectively.



Curtains are often-overlooked as a means of improving the energy-efficiency of windows.  Keep them open in the day (to let in sunlight) and then draw them at night. This will create an extra barrier that prevents heat from escaping the room.  Ideally, you’ll want to use a heavy set of blackout curtains.


When single-glazed windows – and particularly wooden ones – begin to age, it’s inevitable that gaps will form in the spaces where the frame meets the glass.  This might be down to the warping effect of the wood, as it changes shape over time in response to changes in temperature and moisture.  It might also be caused by a degradation of the seal at the edge of the window.  In either case, the result is the same – cold air from outside will be able to pass into your property.

Clearly, this is undesirable.  Fortunately, once the seal around your window has failed, it’s relatively easy to replace it using an inexpensive strip of sticky rubber.  Of, if you’d like a more effective and attractive final window, you might hire a professional joiner to refurbish it with a proper draught-excluding system.

It’s detecting where the draughts have formed that’s the tricky part: even if you can feel a stream of cold air in the middle of your living room, you might struggle to pinpoint exactly where it’s coming from. You can find out by simply turning out the lights and running a candle around the edges of the suspect window.  When the flame flickers, you’ll have found your draught.  Alternatively, you might consider an electronic thermal leak detector – a device which functions like an electronic thermometer, except it works from a distance.  Shine the beam over a leak, and the light on the back of the device will change colour.


If your windows are made from wood, they will require occasional treatments in order to maintain their appearance and effectiveness.  Fortunately, this isn’t a ritual you need perform very often.  Simply scrubbing the frame and re-applying your finish of choice every few years will be enough to guard the wood against rot and warping.  This in turn will reduce the chance of a draught forming, and will help to extend the lifespan of the window itself.

In conclusion

Replacing your windows is an excellent way to improve the thermal efficiency of your home.  But even if you’re prevented from replacing your windows, it’s still possible to improve their efficiency through incremental improvements and maintenance.  If the other elements of the building, like the roof, are substandard, then the windows might not seem an obvious choice for an upgrade.  By the same token, if your windows have not yet degraded to the point where replacement is beneficial, you might wish to delay replacing them, and take some of the alternative measures we’ve mentioned here in the intervening period.

Looking for new windows for your home? Browse our sliding sash or casement windows or find out about our handmade bespoke windows.