Double glazing -v- triple glazing: what’s the best option?

Triple-glazing is often marketed as a better option than double-glazing, especially when it comes to thermal insulation. But is this really the case?

 

If you look at the websites of the big nationals for instance, you could be forgiven for wondering why so many companies are still even selling double glazing when triple glazing appears to be so much better at insulation and soundproofing your home! Here we attempt to debunk many of the myths that surround triple glazing, and clarify the facts to help you make an informed decision that’s right for you.

Example of a triple glazed sealed unit and a double glazed sealed unit.

While it’s true that triple-glazing does offer some benefits, it may not be the best or most economic solution for you.

Triple glazing is a better insulator for your home than double glazing.
The energy performance of windows is measured in U-Values. Lower U-values = a more energy efficient window. Traditional single glazed windows can have a U value in excess of 5. Building Regulations now stipulate that modern double glazing should have a U-value of no less than 1.6.

U-Values for older double glazing used to be much higher. However in recent years the manufacturing process has been greatly improved to provide much more energy efficient units. These improvements have been brought about by the introduction of wider cavities between the two glass panes, low-emissivity coatings being added to the glass to stop heat escaping (glass such as Pilkington K or Planitherm Softcoat Total), the cavity being filled with an inert gas (usually argon) and the use of warm-edge spacer bars (instead of aluminium).

Triple-glazing enables window manufacturers to achieve U-values of 1.0 and lower. So yes, triple glazing can enhance heat retention.  But such U-values are really only of benefit when they are installed into an overall energy saving build, such as in a low energy house or a “passive house”.  Where windows are being fitted into a standard build or as part of a refurbishment project then sealed units offering U-values as low as 1.1 are preferable and easily achievable with double glazing.

With the exception of perhaps the northern reaches of Scotland, the rest of the UK is simply not cold enough to warrant the use of triple glazing. Scandinavian countries such as Iceland, Sweden, Norway, Finland and other far northern countries use triple glazing because temperatures such as -20° C can be quite frequent. Highly energy efficient windows and doors, triple and sometimes quadruple-glazed are absolutely necessary to help reinforce the fabric of the buildings against the cold.

As far as the UK is concerned, there are many who argue that triple glazing simply doesn’t make sense in our climate. It is more costly to produce, produces much heavier sections and has an embodied energy approximately 50% higher than double glazing. Why would home owners pay more when good double glazed windows would easily tick the box?

Triple glazing is a better sound insulator than double glazing.
One of the biggest selling points of triple glazing has been its ability to reduce noise and outdoor sound. The thickness of the glass used is one of the three key elements of the sound insulation. Different thicknesses of glass will block a different frequency, so a combination of panes of varying thickness is more effective at keeping noise out. This is known as asymmetrical glazing. However, (and somewhat ironically!) most fabricators currently appear to offer triple glazed units with standardised cavities and glass thicknesses.

The second key element is the size of the gap between the panes. The larger the gap, the better the overall sound insulation effect. Finally the use of an acoustical resistant gas to augment or replace the inert gas (usually argon) will effectively help reflect noise away.

If sound insulation is important to you then it would be worth considering acoustic glass sealed units (such as Pilkington Optiphon or St Gobain’s acoustic glass, both of which are laminates) or even secondary double glazing instead. Secondary glazing will have a much greater air gap than can be achieved in triple glazing, and can achieve great noise reduction at considerably less cost.

In conclusion – For

  • Triple-glazing offers low U-values suited to specific low-energy and “passive house” projects and can return the value of your investment when fitted as part of these specifications.
  • If asymmetrical glazing is used together with acoustic glass, some noise reduction can be achieved.

In conclusion – Against

  • Higher cost.
  • Reduced light penetration due to additional layer of glass.
  • Minimal savings in energy bills in comparison to the higher cost.
  • Benefits such as noise reduction and solar control can be included in double-glazing for less than the cost of a standard triple-glazed unit.
  • Overall greater weight than a double glazed unit could pose problems for your windows – sashes dropping can be an issue.

Please do not hesitate to contact us for any further information. We look forward to hearing from you and hope to see you soon! 🙂

What is smart glass?

Glass has got intelligent. And we think it’s all the better for it.

Generally used in conservatory and lantern roofs, the term “smart glass” or “intelligent glass” usually refers to the new generation of glass systems that feature additional built-in properties. This can include solar control, privacy glass and self-cleaning glass. There is now a growing demand for better performing conservatory roofing systems, both for brand new installations and for the emerging replacement sector. Glass is at the very heart of the thermal and acoustic performance of any conservatory and smart glass is not only far quieter but can also regulate temperature so your conservatory can be used all year round. It can reflect unwanted heat and glare from the sun in the summer, yet will also help to retain warmth during the winter months, and is almost three times as efficient than standard double glazing.

Smart glass can also filter out harmful UV rays and use self-cleaning technology, reducing the frequency of cleaning required and keeping your roof looking better, for longer.

TYPES OF “SMART GLASS” AVAILABLE

Pilkington Activ™
This was the world’s first self-cleaning glass. It’s basically the same as conventional glass, except for a unique permanent dual action coating. It works in two ways: first it uses daylight to break down organic deposits (such as dirt) and then uses rain to wash the dirt away. Pilkington Activ™ also dries faster, leaving the glass clean and with less streaks. It’s an ideal solution for conservatory roofs, orangeries, glass extensions, skylights and windows in hard to reach areas. The Pilkington Activ™ range comprises of several different types of self-cleaning glass:

  • Pilkington Activ™ Clear – self-cleaning glass.
  • Pilkington Activ™ Bronze – a tinted self-cleaning glass that combines self-cleaning with solar control.
  • Pilkington Activ™ Blue – a tinted self-cleaning glass that combines self-cleaning with medium solar control.
  • Pilkington Activ SunShade™ Neutral – a coloured glass that combines self-cleaning with superior solar control.
  • Pilkington Activ SunShade™ Blue – an attractive blue tinted glass that combines self-cleaning with superior solar control.

Check out the Pilkington Activ brochure on our website here >>

Dynamic SMARTGLASS®
This is an exciting new product by Clayton Glass – the industry’s first automatically self-tinting, glass technology for conservatories, orangeries and lantern roofs. In the middle of summer SMARTGLASS® Dynamic will change from a clear state in the morning to a darker blue one during the day, where solar control and light shading is needed most. Then as the unit cools, it will return to clear at the end of the day and into the night. (This reminds us a bit of those reactions lenses you can have in your glasses!). At all other times of the day and season this glass will offer various semi-tinted states, dependant upon the surface temperature of the glass. In its clear state, this glass offers a similar light transmission to a standard clear glass unit.

SMARTGLASS® Dynamic by Clayton Glass, shown in its clear and tinted states.

SWITCHABLE PRIVACY GLASS
Almost like magic, this glass can turn from clear to opaque instantly. Truly the stuff of “Grand Designs”, switchable glass is operated by a simple electrical switch, controlling the opacity of the glass from clear to translucent. The opacity is down to a special Polymer Dispersed Liquid Crystal (PDLC) film which includes conductive interlayers and allows you to change the visual appearance of the glass at the flick of a switch.  The latest generation of switchable double glazed smart glass windows combines the benefits of improved thermal performance with the immediate control over privacy and security. The PDLC can be applied to any type or thickness of glass including toughened, laminated and double glazed sealed units, offering a number of glazing solutions for both the domestic and commercial markets.

Now you see it, now you don’t! Switchable glass used in a shower screen to give privacy. Ok, we know it’s not a window or door, but hey, we liked this and think it looks cool!

SOLAR CONTROL GLASS
Excess heat and glare caused by the sun can be a major source of discomfort in some indoor environments, especially those with glass roofs, conservatories or with large glazed areas. The latest solutions for solar control reflect and filter the sun’s rays, allowing natural daylight into the room, but without uncomfortable visual glare. Rooms can be kept cooler during sunny periods, reducing the need for air-conditioning. A range of solar control glass solutions are available, from a number of trusted manufacturers such as St Gobain, Pilkington and Reflex.

Solar control glass can be incorporated into double glazing window with combinations of other glass, such as self cleaning, Low E and decorative glass. Combining solar control glass with Low E thermal insulation in one double glazed unit offers optimum temperature comfort all year round.

Talk to us about the different glazing options that are now available for your home. We hope to see you very soon! 🙂

What is an insurance backed guarantee and why do I need one?

The low-down on Insurance Backed Guarantees and what they mean for you, the customer.

 

For all replacement window and door installations that are notifiable to “competant person schemes” such as FENSA or CERTASS (we are members of both) the installer is required to provide the following insurance policies for their customers (it is a government requirement that companies must have certain insurance policies in place where applicable).

  • Insurance Backed Guarantees (IBG): Replacement of windows and doors in domestic dwellings must have an Insurance Backed Guarantee provided.
  • Deposit Protection: If a CERTASS or FENSA Registered Business takes deposits in advance of installations, they must give some form of deposit indemnity. Deposits may be guaranteed by, for example, trade association Deposit Indemnity schemes, or credit card protection.
  • Guarantee or Warranty: Registered businesses must provide a guarantee or warranty covering the cost of completing rectification work in respect of installation defects for a period of ten years.

Deposit protection and Insurance Backed Guarantees can be provided by a number of companies – we have been using Quality Assured National Warranties (QANW) for many years now. Watch their short video below which explains the benefits of IBGs to consumers.

If you have any further questions about your insurance backed guarantee or deposit protection, please give us a call on (020) 8868 1133 or check out the QANW consumer website here >>

We hope to see you again very soon! 🙂

Solutions for planning and conservation areas

Conservation area woes – now you can have the best of both worlds with our Residence 9 windows!

 

“I’d love to replace my rotten old timber windows with a maintenance free option but I’m in a conservation area and need to obtain planning permission. The council won’t allow uPVC windows – what can I do?”

A conservation area is an area of specific architectural or historical interest, the character or appearance of which is desirable to preserve or enhance. Many towns and villages rely on historic windows for much of their architectural impact and character and inappropriate, poor quality replacement windows can easily erode traditional features on historic buildings.

ARTICLE 4
Article 4, as it is known, is when a planning authority applies to restrict development rights in a conservation area and replacement windows will then need to be approved by planning. Some planning authorities precluded the use of modern materials because the window designs were considered inappropriate in size, shape and design. However with the recent introduction of new profiles that are designed to resemble traditional wood, some authorities have now adopted a more modern approach and will approve the use of specific profiles because of their consideration of the Article 4 directives. Residence 9 has been specifically designed to replicate the documented historical window designs from the period.

Looks like wood – Residence 9 Window showing authentic looking ovolo/putty Georgian bars, flush sashes and 45 degree “timber effect” welds.

The design brief for Residence 9 was to extract the key principles, shapes and dimensions from the Article 4 Conservation Area guidelines for windows and integrate market leading technology into the design using virtually maintenance free materials.

Residence 9 is thermally and acoustically brilliant. It features the latest security, maintenance and performance innovations, whilst appearing completely traditional. Your windows won’t warp, swell, flake or need sanding and painting.

  • Residence 9 has nine chambers and is 100mm wide, resulting in superior thermal, acoustic, strength and security performance.
  • Achieves a certified window energy A+ rating
  • Can accommodate 44mm triple glazing and 28mm double glazing.
  • Attains U-values of 0.8 with triple glazing, PassivHaus Standard, and 1.2 with double glazing, far surpassing the British Building Regulation requirements.
  • All of this contributes to lower energy bills, keeping you cosy in the winter and cool in the summer.
Interior view of a Residence 9 window clearly demonstrates the authentic timber styling and feature monkey tail handles.

ATTENTION TO DETAIL
Residence 9 windows are not only stylish, they will withstand the test of time too. They include state of the art design features and champion British craftsmanship using time honoured traditions and modern manufacturing processes. With a range of splendid styles and configurations, Residence 9 allows you to create an individual design statement for your home – choose from a vast colour palette and a series of decorative options such as peg stays, authentic looking Georgian bars and weather bars to truly personalise your windows.

The devil is in the detail – these small but very important design features create an authentic looking window beyond comparison.

Download our latest Residence 9 brochure from our website here or give us a call and have a chat with John about how Residence 9 could work for you. We hope to see you soon!

 

The double glazing industry explained

Our handy quick guide about the double glazing and conservatory industry.

DOUBLE GLAZING
The term double glazing refers to windows and doors that are glazed with sealed units – two panes of glass with a spacer bar around the edge. The edge is sealed with a special sealant (usually today known as a “warm edge spacer”) to prevent air and moisture entering the sealed unit. Sealed units can be used in uPVC, aluminium and timber windows and doors, although timber traditionally used much thinner units.

Example of a sealed unit fitted into a uPVC window profile.

Although the first double glazed units were experimented with in the 1950s, it was in the early 1980s that the double glazing industry really began to grow and develop. Windows had, until that time, usually been manufactured in steel (such as Crittall windows) or timber. Aluminium windows and doors, often in a matt silver anodised finish, were manufactured and installed into hardwood subframes (often Brazilian mahogany). By the mid 1980s, many small companies were manufacturing their own aluminium windows and doors. Powder coating meant aluminium was now available in white and other colours such as brown and black. Towards the late 1980s, uPVC windows and doors started to become more popular. Manufactured from a thermoplastic polymer known as unplasticised polyvinyl chloride, uPVC is a rigid and cost-effective plastic, ideal for building materials.

Today, both aluminium and uPVC are available in a wide range of colours and the profiles are now direct fix, so no subframes are required.

SYSTEMS, FABRICATORS AND INSTALLERS
Both aluminium and uPVC windows and doors are are manufactured from a series of profiles that are cut and crimped or welded together, such as the outer frame, sash, transom and beads. Together, the profiles make up one complete system, and the companies who design and manufacture them are known as extrusion or systems companies. There are around 25 or so main uPVC and aluminium extrusion companies who supply the UK market.

Lengths of residential aluminium window profiles

These systems companies supply businesses who then manufacture the windows and doors – these are known as the fabricators.

Fabricators manufacture the finished window or door, cutting and assembling the profiles together and adding hardware (locks, hinges, handles) along with weatherseals and gaskets. In the UK currently there are around 4500 window and door fabricators, of which some 1500 fabricate uPVC, 800 aluminium and the rest are joiners, or timber window and door manufacturers. Some companies manufacture more than one material type and may supply and fit direct to the homeowner, whilst others may supply only to the trade, such as builders or specialist window installers.

Fabricating uPVC windows

There are over 12,500 specialist double glazing and home improvement companies who fit windows and doors in the UK, primarily in the domestic sector. Many small companies used to fabricate their products and then install them too – it was common back in the 1980s and 1990s. However with the introduction of the new building regulations back in April 2006 (known as Document L), most installers today now prefer to focus primarily on sales and installation.

CONSERVATORIES
A conservatory consists of three main parts: The base and foundation (including dwarf walls), the elevations (window and door frames), and most important of all, the roof.

Conservatory roofs are a specialist engineered product designed to withstand the elements and support the weight of the glazing material. The conservatory walls (including windows and doors) need to be structurally strong enough to support and secure the conservatory roof above it.

Similar to windows and doors, the roof is manufactured from a series of profiles, components and glazing materials. Due to structural requirements, the material tends to be aluminium or aluminium clad with uPVC. There are a number of specialist conservatory roof systems, including Synseal Global, Ultraframe Quantal, and K2 who manufacture the roofs and also supply a network of around 260 conservatory roof fabricators.

A popular variation of a conservatory is the orangery. A more solidly built structure than a conservatory, an orangery tends to have a solid roof with roof lanterns and is more like a proper extension with lots of glass.

Conservatory elevations and roof installed by Ruislip Windows

If you’d like any further information on any of our products, or would like to arrange your free no-obligation quotation, please give us a call on (020) 8868 1133. We hope to hear from you soon!