How do I know which are the best triple glazing materials?

Triple glazing is one of the most efficient ways to insulate your home against the elements. Triple glazing has 30 – 50% better heat retention properties than double glazing and with U-values of 0.7, it is also twice as efficient. But knowing where to start when choosing your triple glazing materials can be a challenge, especially since there are so many styles and materials to choose from.

The choice of windows has a big impact on the look of your home so great care should be taken when deciding which style to go for. Often though, the style of your home will dictate the window style as well.

There are 6 different window styles that fit most homes in the UK:

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Standard Windows

The most popular type of window is the standard window, also known as a casement window. These windows are fixed into the frame, and top-hung or side-hung. The multiple window panels contained in a standard window, allow great control over the amount of air that enters the home. Their simple design make these window a great match for most homes designs.

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Conservation Windows

Like the name states, conservation windows match the frame and material of the original window. Homes in a conservation area has to comply with strict building codes, preventing them from changing the original look of the house. By installing conservation windows, you can have all the modern convenience of a triple glazed window while maintaining the traditional aesthetic. The windows are made with either wood or uPVC frames that mimic traditional wooden materials.

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Sash Windows

Although the design also hails from the Victorian or Georgian period, modern sash windows are practical, beautiful and come with triple glazing. Their large, unobstructed glass panes allow for maximum light to enter the home, and the opening mechanism gives great control over the amount of outside air coming in.

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Tilt Windows

Tilt windows put a modern spin on a traditional window by allowing users to tilt and turn windows for optimal ventilation. Titled windows have the added benefit of being easy to clean from the inside.

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Bay Windows

Bay windows are very popular in British homes. In addition to their traditional aesthetic, its clever placement of windows opposite each other allows for natural cross-ventilation.

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Cottage Windows

These windows consisting of multiple small glass panes were originally found in cottages throughout the country side. The modern version rather uses a single panel on which glazing bars in installed to create the same look. Having one larger triple glazed panel that consists of 3 layers, instead of a series of smaller windows each with 3 layers, makes window leaks less likely.

Window Frame Materials

In addition to choosing your window style, you must also choose the material that the frame will be made of. Most of the 6 styles are available in wood, uPVC, aluminium, and aluminium-clad. Your triple glazing manufacturer will be able to give you more information on which style is available in which material, and ultimately, which solution will suit your home and budget best.

WOOD

Wood is the traditional material of choice when it comes to window frames. Beautiful and able to withstand all types of weather, wood requires more upkeep than modern materials. If you choose to use wood as a frame material, make sure that it comes from a sustainable source.

UPVC

uPVC or unplasticized polyvinyl chloride, is known for being a strong, long-lasting, and easy to maintain window material. Unlike wood, uPVC will never warp, rot or fade. It is a molded material, which means that it can support an endless variety of finishes, colours and even textures. It is this versatility that makes it a great option for conservation windows that have to imitate the original wooden design. uPVC has the added benefit of being water and fire-resistant, and impervious to scratches and other damage. uPVC is a recyclable material, giving it a green credit as well.

Aluminium

Like uPVC, aluminium frames are very tough, and have the added benefit of being extremely lightweight and resistant to corrosion. Aluminum frames come in a variety of colours and styles. Aluminum is unique because it is a recyclable material that doesn’t lose any of its properties during the recycling process.

Aluminium-clad

Alu-clad frames are basically upgraded wooden frames. Aluminium cladding is added to the outside of the wooden frame, increasing its strength, durability and ability to withstand the elements. This provides all the benefits of aluminum without compromising the interior’s traditional wooden look.

Which material is the most energy efficient?

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To fairly compare the energy efficiency of the different materials, there are few factors that must be considered. Aluminium windows for instance are highly durable but their manufacturing processes make them less energy efficient. Softwood windows have a low manufacturing impact, but they do not last as long.

To reduce the environmental of wood, it’s important to carefully consider the source of timber, it’s treatment and maintenance options. Wood should be sourced from Forest Stewardship Council certified sources. This would typically be durable temperate hardwoods like oak, larch and sweet chestnut, with sapwood explicitly being excluded. Transportation of the wood will add to its environmental impact so getting UK-produced wood is essential.

Painting the frames will further add to its environmental impact. Naturally durable wood species that don’t need painting is the best option, otherwise an environmentally sensitive product must be used for treatment. Untreated frames will change colour of time so if the specific tone is a priority, then it is best to get windows made in another material.

Aluminium-clad frames successfully combines the environmental sustainability of softwood with the incredible durability of aluminium, taking its lifespan from 30 to more than 40 years. Both materials are fully recyclable, requires little to no maintenance and has great durability. Because wood has very low thermal conductivity, aluminium-clad wooden frames are rated as good thermal insulators.

uPVC has made great strides as a building material because it is light-weight, durable and requires very little maintenance. Thermal conductivity is low, so it is also a good insulation material. On the green side however, uPVC is being made from non-renewable petroleum and because of that loses a lot of its environmental credibility. Frames will typically last 25 – 40 years and although very difficult to repair, the material is down-cyclable.

When it comes to carbon footprint and thermal performance however, wood is the clear winner. It was found to be four times greener than aluminium, which is the least green material. Wood is also twice as energy efficient as uPVC, which is the second greenest material. (source)

Properties Wood Aluminium-clad Aluminium UPVC
Cost £260-£460 / sqm £280 - £490 / sqm £ 250 - £480 / sqm £150-£400 / sqm
Lifespan 30 years 40 years 30 years 25 years
Maintenance Needs periodical sanding and resealing to prevent cracking Maintenance Free, except for routine cleaning and maintenance of hinges and catches Maintenance Free, except for routine cleaning and maintenance of hinges and catches Maintenance Free, except for routine cleaning and maintenance of hinges and catches
Durability durable highly durable highly durable durable
Corrosion Resistance does not corrode can be prone to corrosion over time can be prone to corrosion over time does not corrode
Fade / UV Resistance Can fade easily if not treated with UV-resistant oil, paint or varnish High UV-resistant coatings prevents fading High UV-resistant coatings prevents fading Highly resistant to fading
Thermal Conductivity very low medium high medium
Flammability high medium low self-extinguishing
Design Options customizable highly customizable highly customizable mainly while

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To thoroughly determine the energy efficiency of a triple glazed window unit, the energy balance has to be taken into account as well. Energy balance is the difference between the amount of heat from sunlight that a window transfers into your home, and the amount of heat that escapes through the window from inside. This it he most accurate way to determine the efficiency of a window.

The energy balance is dependent on a few variables though: the orientation of the window with regards to the sun, the exact geographical location of the home in question and of course the material that the frame is made of.

A window frame’s energy efficiency then can’t be fully evaluated in isolation – all of these factors should be considered. This is where a professional glazing consultant will be able to make a recommendation based on your specific property and requirements.

The window frame material that you choose will depend on what the design of your home dictates, but ultimately it will also be determined by its inherent properties and the cost involved. We trust this handy guide has given you the information you need to ask the right questions and to make the right choice.

Published on : 1st February 2017

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