The benefits of high quality windows - Westbury Windows and Joinery

The benefits of having quality windows during the winter


The performance of quality windows speaks for itself during the winter, but how can they help us to use less energy and lower our carbon footprints too?

The weather is cold and dark, and January seems to have lasted an age. Over the past week or so, we have all noticed a freezing bite in the air, and we have been turning up the thermostats to keep us feeling snug at home. 

Incidentally, keeping warm in the colder months is one of the biggest reasons for replacing windows.  Having old or poorly performing products in your home can make you feel cold even when the house is sufficiently heated. Anyone who has lived in a property with poorly fitting or single-pane windows knows how a cold draft can put a shiver down your spine! So if you’ve been thinking about getting them replaced, it might be worth investigating as the temperatures start to fall. 


Newly installed, thermally efficient windows will not leak cold air into your home, and they will help you to save on energy as a result. In the past, most people would start doing their outside renovation work in the spring, as conditions are drier and laying bricks is easier. These days, they are purchased all year round, as more and more builders are finding ways to work around our somewhat temperamental and unpredictable climate. You might find that you get quicker lead times on doors and windows during the winter months, so keep this in mind when you are making your renovation plans.  

Reducing your carbon footprint 

Over recent years, we have seen our temperatures rise, and our summers become warmer. While our focus might naturally shift to air conditioning and ventilation systems, there is still a lot to be said for keeping our homes warm during the colder months. Concern over the environment is making homeowners more aware than ever of the value of energy-efficient windows. Essentially, they can make a big difference to the amount of heat your home needs, providing they are of superior quality. 

Double glazed and triple glazed windows consist of two or three sheets of glass, with an air gap in between to create an insulating barrier. Particularly efficient windows have gaps filled with either Argon or Krypton, which are clear, non-toxic gasses that significantly decrease heat transfer. According to the Energy Saving Trust, double-glazing cuts heat loss through windows by half. You can imagine how it might reduce your household’s carbon footprint! What most people do not realise is that quality windows can help in the warmer weather too, by reducing solar heat gain inside your home. 

Understanding U-Values

You can quickly determine a window’s ability to retain heat by looking at its U-Values, which is a measurement of a material’s insulation efficiency. U-Values tell you how much heat a window is likely to let through. The lower the U-Value, then the better the energy efficiency a product has. 

Many companies advertise a low U-Value number but measure from the centre of the glass in the pane, which is usually the section of the window with the highest insulation. Make sure you check the U-Value for the whole window, as all products experience more heat loss around the edges of the pane. 

Back in 2018, Part L building regulations for standard replacement doors and windows specified that a product should have a U-Value no higher than 1.6 for windows, and 1.8 for doors. Windows that have U-Values of just 0.1 or 0.2 under the regulation threshold do not make any difference to your carbon footprint, or energy bills for that matter.   

Thermal performance through outstanding design

We design our timber window frames, sashes and doors with deep inside-to-outside profiles, therefore improving the thermal performance through the wood components. This technique was initially mastered by Scandinavians many years ago, to help them keep their homes warm in the cold weather. They used a standard frame depth of 115mm, which is what we use at Westbury today. Our sashes are 68mm deep, meaning they can incorporate a thicker and broader choice of energy-efficient and sound reducing glass. 

Westbury Windows and Joinery expertly construct windows with a whole product U-Value of 1.4 W/m2K based on double-glazed glass and 1.1W/m2K, based on triple-glazed 4mm thick glass with a centre pane value of 0.6W/m2K. At Westbury, testing is something we do every time we develop our designs or when the regulations are changed. When Building Regulations were altered most recently, we spent three years getting every one of our products independently tested. Two separate independent professionals in a controlled environment carry out the tests at a UKAS accredited centre (United Kingdom Accreditation Service). They also tested for weather durability, assessing the window’s air permeability, water tightness and wind resistance. 

With so many products, testing them all is an expensive and lengthy process. Still, we know that our doors and windows are the best performing products on the market, and we have the results to prove it. 

Condensation: the tell-tale sign of heat performance

Condensation is something that people often worry about when it comes to glazing, who assume that it means the window is flawed. It can actually be a sign of superior energy efficiency. If the temperature of the glass drops below the dew point temperature, water vapour from the surrounding atmosphere condenses into water droplets on its surface. If you discover condensation on the outer side of a window on cold mornings, this is an indication that the glazing is performing well and heat is not escaping out of the window.

If you notice condensation between layers of glazing, the gas inside has escaped, and you need to replace the window. Condensation inside your windows indicates the cold air is coming in, and meeting the heat inside to create droplets. The dampness creates mould, which looks awful and is not great for your health. Condensation also causes issues if the manufacturers have made the window frames from an inferior timber. The timber will suck up the water droplets, which causes the joints to move. The movement can break the outer layers of the paint covering them, subsequently allowing more water in. Over time, rot sets in and the wood starts to decompose. It is easy to see why timber windows have not had the best reputation when it comes to performance!

Amazing Accoya®

Alternatively, engineered timber is a fantastic material to use for windows and doors. It can result in beautifully detailed frames, which are strong and durable. At Westbury Windows and Joinery, we have investigated the performances of different timber materials, joinery methods and fitting techniques to result in a high performing window product.

We use engineered timber with Accoya® on the outside layer, resulting in exceptionally low thermal conductivity. Accoya is a revolutionary material made from fast-growing, sustainably sourced Radiata Pine. These are quick growing trees (28 years) with minimal wastage in production. Once felled, the pine undergoes a process that compresses and bonds laminates (thin slices) of the pinewood, rotating the grain by 90˚ at each layer. This cross-lamination gives Accoya up to 75% greater dimensional stability than solid hardwoods. The Accoya timber undergoes a process called acetylation, which re-plumps the cells of the cut lumber, making the timber harder and termite resistant. 

We then spray-apply our timber windows with three coats of Teknos; a water-based, micro-porous paint explicitly formulated for external use on timber. The paint creates a layer that protects the external timber, making it resistant to bacteria, mould, and UV attack.