How to choose windows

Wooden windows

Offers the lowest thermal conductivity, meaning less heat lost through the frames, and provides a traditional look. Timber is the highest performing material in terms of energy efficiency, as it's a natural insulator that absorbs and retains heat.

Wooden window frames can be made from both softwood and hardwood. Softwood is faster growing and more plentiful, so it's cheaper. Hardwood grows slower and is more durable, so tends to be more expensive. Modern timber frames are engineered to be stronger, meaning they will not warp or bow, and can also be treated to resist rot and fungus.

Timber offers a traditional look with the benefit that it can have a stained or painted finish. It's the only material that can be repainted a different colour at a later date, so personalising the look of your home becomes even easier.

Wooden windows are seen to be most attractive, but natural materials such as wood require more looking after to keep them at their best and they are more expensive than other options.

uPVC windows

Long lasting and low maintenance, offering high performance at affordable prices. uPVC is a good all-round material that makes smooth and stylish frames which will never rot, flake or rust.

uPVC is a popular choice for windows as it offers fantastic value for money. Although, for some, lacks the unique charm of other materials. However, it is now possible to buy uPVC windows designed to emulate traditional timber frames, to such an extent that it can be difficult to tell them apart.

uPVC windows are still among the most energy efficient available and, with excellent double glazing, can achieve up to an A+ Windows Energy Rating.

Available in a range of colours. uPVC windows can be made with external frames one colour and the internal frame another to match interiors.

Aluminium windows

Aluminium windows are used in structural glazing and other commercial construction projects due to its strength. In domestic properties, this allows for a much thinner window frame and a larger glass surface area, letting more light into the room.

Aluminium windows feature a thermal barrier in the frames, which reduces heat loss through the frames. In the last 10 years, thermal barrier technology has improved massively, and aluminium windows can now achieve almost the same high energy ratings as uPVC windows.

Aluminium windows are extremely weatherproof and low maintenance. Unlike other metals, aluminium does not corrode, so window frames will not rot, flake or rust. A powdered coated finish allows a wide range of colours to be chosen for the frame.

Casement windows

Casement windows have always been the most popular window style. They can be hinged on the side to open left or right, or hinged to open upwards. Extremely versatile, they can be designed to suit a range of properties. The modern technology, with multiple locking points along all sides of the frame, makes a casement window extremely secure.

Tilt and turn windows

Tilt and turn windows possess a dual hinge design that tilts and open inwards using hinges at the bottom and side. Tidy and efficient, these windows have been designed for flats, apartments and other upper storeys, providing secure ventilation and an easy way to clean the glass inside and out.

Sash windows

Amongst the most traditional window styles. Historically made from timber, sash windows can now be made from uPVC, for a classic design that fulfils modern day performance requirements.

There are several different styles of sash window available, modelled on designs from the Georgian, Victorian and Edwardian periods. Designs vary depending on the era, but tend to have a thicker frame depth and a deep bottom rail.

Cottage windows

Cottage windows are casement windows with Georgian bars applied to add a traditional finish to your property. Internal glazing bars sit between the glass panes and keep your windows easy to clean, whereas external bars sit on the surface of the glass.

Another option is diamond or square leaded glass designs to replicate traditional window styles.

Traditional houses

Houses built before the 20th century originally had wooden windows, and still suit these today. Georgian houses, 1930s semis and Victorian terraces are all period properties built with wooden sash windows or period detailing. Modern uPVC windows can sometimes replicate these styles, but there's no replacement for timber. In some cases, replacing period windows with uPVC can devalue a property, so take care when replacing windows on traditional houses.

Suburban housing

Properties in housing developments built from the 1960s onwards can be replaced with white uPVC. Depending on the colour of the house brick or render, coloured frames can add a unique touch.

Modern Architectural

For that stylish contemporary look, there's no better choice than sleek aluminium frames. Used in structural glazing, aluminium is a strong material that can hold larger glass units to increase the amount of natural light. Aluminium frames sit flatter than uPVC frames and have slim profiles that allows for an increased glazed area with an unobtrusive frame.

Single glazing

Installing single glazing is still a requirement on occasion where planning or conservation regulations apply. Along with timber frames, single glazing helps a property retain its period look. To improve insulation under these circumstances we recommend secondary glazing.

Double glazing

Double glazing is one of the most effective ways to improve the insulation of a home, creating a warm and comfortable living environment.

Everest double glazed window have two panes of glass are joined by a spacer bar. The gap between the panes traps warm air, slowing the escape of heat from a building. In addition, the best windows introduce an inert gas, such as argon, which further limits the movement of cold air.

In the UK, all new buildings must install at least 1.4 U-value or C rated double glazed windows as standard, but many companies are offering double glazing that can achieve an A or even A+ rating.

Triple glazing

Triple glazing contains a third pane of glass, creating an extra cavity which traps warm air and reduces heat loss through the sealed unit.

Is triple glazing really any better than double glazing?

A common misconception about triple glazing is that the improvement in thermal performance is due to the extra pane itself. However, it's more about the types of glass and coatings used, the gas filled sealed unit and the distance between the panes.

Everest triple glazed windows have one of the highest performing glazing units on the market with an industry-leading lowest U-value making it ultra energy efficient. Choosing energy-efficient Everest windows can help lower your energy bills and reduce your carbon footprint.

If your priority is noise reduction, we recommend noise-reducing double glazing because the middle pane in triple glazing can increase sound vibration and amplify sound transference.

As the Future Homes Standards are introduced, the energy efficiency of a home and U-values for windows will become more important. At Everest, we believe that triple glazed windows will become a requirement in all new build houses as the standards for the fabric structure of buildings keep increasing.

Secondary glazing

A practical alternative to double glazing for conservation areas

If you live in a listed building or conservation area it may not be possible to replace your windows. In this instance secondary glazing would be the perfect option to reduce noise and cold draughts.

Everest secondary glazing has an additional window installed directly inside of the existing frame. It can help your home achieve thermal, security and noise reduction benefits, whilst remaining invisible to the outside.

Low-E glass

Low emissivity glass has an invisible, thin coating applied to its surface that reflects heat. It is strategically placed on the inner pane of glass to help keep heat indoors and to maintain a comfortable temperature.

Low iron glass

Windows that contain low iron glass are noticeably clearer. They allow a higher level of light to pass through compared to older glass types, which sometimes have a slightly green tint.

Security glass

Security glass is available in a range of sizes and thicknesses depending on your security needs. Typically, laminated glass is 6.4mm thick (compared to 4mm for standard glass), and contains a thin plastic interlayer that prevents the glass from breaking. Toughened glass is up to five times as strong as ordinary glass of the same thickness.

Used as an outer pane in a double glazed unit, this provides an extra level of security to the window as a whole. Toughened glass must also be used for fixed lights in side panels to doors, as well as in windows close to the ground.

Noise reducing glass

Noise reducing glass contains an inner pane that is 6.8mm thick supported by an outer pane that is an incredible 6mm thick. Together, they provide excellent sound insulation. A thin and lightweight solution to noise problems.

Coloured glass

Add coloured shapes, patterns and bevelled designs into the glass itself. Decorative glass looks beautiful in top hung fanlights – the top sashes of casement windows – as well as feature windows in halls and stairwells. Coloured glass is similar to stained glass windows, but it doesn't require leading to hold the glass together.

Leaded glass

Stylish strips of lead are a purely visual benefit that can be added to your window in order to make it more aesthetically pleasing.

Obscure glass

Obscure glass creates a 'cloudy' effect, also known as privacy glass. There's a variety of textures available, such as leaves and flowers, as well as grainy patterns.

Weather tight seals

Until very recently, window seals were thick, black and rubbery, and stood out starkly against white frames. Seals are now slim and discreet, offering better insulation and contributing to much higher energy performance.

Rubber seals tend to flatten once it is subject to repeated pressure, altering their shape and ultimately hindering their performance. Eventually, they can collapse and this is one of the main reasons why older windows fail after a number of years.

Everest seals are made from a soft PVC and will spring back to their original shape every time. Because the seal is co extruded, it will never pull out of the groove, ensuring consistent weather performance for the lifetime of the window.

Handles

Window handles come with key locking as standard and are usually available in a range of colours and metallic finishes to match the frame colour.

Sash window furniture

The key to achieving an authentic-look sash window is in the furniture. Small metal hook pulls sit at the foot of the sash, with fasteners locking the window together.

Traditional ironmongery

Modern windows can be made to look exactly like their traditional counterparts with traditional style handles, such as monkey tail or tear drop handles. Windows can also be decorated with peg stays, the period version of modern-day friction stay hinges, that keep a window casement open at the angle you want.

Other ways to accessorise your new windows include different frame colours (including two-colour frames), decorative glazing and period features, such as sash horns and Georgian bars.

Internally beaded windows

Window glazing is held in place against the frame with a small strip called a 'bead' which runs along all the edges of the window sash.

Early uPVC windows had the option of external beading, but this has largely been dropped due to security concerns. Window beads used to be a lot weaker and offered an easy opportunity for burglars to simply peel them away and remove the glass.

Most windows nowadays have internal glazing beads, which is the most secure option.

Multi-point locking

There are many more options regarding locks, offering varying levels of safety and security.

Technically, a window with just two locking points can be considered "multi-locking." The more points that can be locked, the more secure it is. There isn't a standard number of mechanisms, but if you can find a window that has eight or more locking points, you have yourself an incredibly secure window.

Bi-directorial locking adds a layer of complexity in the frame that prevents the intruder from being able to jemmy your window out of place.

Key lockable handles

All modern window handles are key lockable, making it difficult for potential intruders to simply wriggle your windows open. It also adds an extra safety feature for top storey rooms accessible by children and vulnerable. It is recommended that you leave your key inside the lock, however, so it is accessible in event of an emergency.

Hinge-side security brackets

Some uPVC window frames incorporate tough, interlocking brackets that secure the outside of a window sash when fully shut and locked. This means that if an intruder tries to lever the window on the hinge side, the brackets will prevent them from being able to lever the window out of place.

Egress hinges

Used for fire escapes, egress hinges allow a casement window to open fully outwards in order to provide an emergency exit.

Opening restrictors

Opening restrictors limit how much a window opens, either by connecting the sash and the frame via a cable, or by fitting key-lockable restrictors that allow windows to open no more than a couple of centimetres wide for ventilation purposes.

The Royal Society for the Prevention of Accidents reports that 4,000 children under the age of 15 are injured falling from windows every year. Something that could easily be prevented by using window restrictors.

Lockable ventilation & night vents

Windows have the option of leaving a small, one inch gap when closing known as the night vent position that many people use as a means of ventilation. However, leaving a window on the latch is far less secure than shutting a window fully, and can present an opportunity for a potential burglar to prise open the window.

New windows can be provided with 'trickle vents' instead, which provide background ventilation without compromising the security of your home.

WER rating

The British Fenestration Rating Council (BFRC) created the WER rating (Window Energy Rating) in order to simplify how effective a window is. The rating system offers grades from A-G (with A being the highest rating). If the window is rated higher than an A it will be followed by a number, and anything above an A10 becomes A+. In October 2015, the BFRC introduced the A++ rating for windows that achieve higher than A20.

The WER rating is made up of three key elements: U value, solar gain and air loss through leakage.

1. Thermal efficiency (U value)

A window's U value is the technical way to measure heat loss through a type of building material, such as a brick wall or tiled roof. U values are calculated by the equation W/m2k, which measures heat loss in watts (W) per square metre of material, when the temperature (k) outside is at least one degree lower.

The lower the U value, the better the insulation provided by the material. Single glazed windows have a typical U value of 4.8-5.6W/m²K. Modern double glazing can achieve a U value as low as 1.4W/m²K, and triple glazing is even more energy efficient, reaching 0.6W/m²K.

As the Future Homes Standards are introduced, the energy efficiency of a home and U-values for windows will become more important. At Everest, we believe that triple glazed windows will become a requirement in all new build houses as the standards for the fabric structure of buildings keep increasing.

Everest uPVC triple glazed windows and double glazing windows have an ultra-low U-value.

2. Solar gain (G value)

Solar gain is another factor that can boost a window's energy rating. Not only are windows now designed to reduce heat escaping, but they can also let heat in by capturing the sun's rays. Solar gain is measured by the G value, on a scale between 0 and 1, with a high number indicating high solar gain.

Factors that influence the solar factor include the number of panes, the type of gas between them, and also the type of coatings added to the windows, as they dictate whether the glass absorbs or reflects the heat.

Contrary to what you might think, solar gain windows do not always lead to overheating. The UK has a relatively cool climate and relatively little sunshine, so overheating is rarely a problem. For rooms where sun streams in during the afternoon, it could be worth considering upgrading to triple glazing. The level of solar gain is actually less than double glazing, due to the extra pane of glass and cavity.

3. Air leakage (L value)

Air leakage occurs when there is a weak point around the window frame, such as the seals. Most modern windows are fully airtight, and should have an air leakage factor or L-value of zero (0.00W/m²K).

Air leakage is not to be mistaken with ventilation. Ventilation is a controlled system, letting in small amounts of fresh air to reduce stuffiness and improve air quality, whereas air leakage will compromise the energy efficiency of your window.

What you should expect from your new windows

Finally, when considering new windows, these are all the requirements your new windows should have:

• Be easy to maintain and clean
• Let in a good amount of light
• Look good and be aesthetically in-keeping with your home
• Be highly secure with multi-point locks and mechanisms
• Have glass that can't be removed from outside of the home
• Have a high energy rating (A++ is currently the highest) to reduce energy bills
• Be made-to-measure, therefore fit perfectly into the aperture of your home
• Keep out draughts
• Not move or rattle when the wind blows
• Long lasting guarantees that cover all areas of the window (not just the glazing)
• Add value to your home