DOORS , WINDOWS & FITTINGS
TRIPLE GLAZING VS VACUUM GLAZING – WHICH IS BEST ?
The Future Buildings Standard which is looming over the horizon in 2025 is likely to mean a big increase in the use of triple glazing in order to meet the lower U-values that will be required . However , specifiers are starting to consider vacuum glass as an alternative but which is better ? Well , it depends ....
What does the Future Buildings Standard say about u-values ? The Government has outlined its plans to deliver a “ zero carbon ready ” building strategy through its Future Buildings Standard . It aims to ensure that no new buildings from 2025 will require further retrofitting , with an uplift in energy efficiency standards , improved ventilation and requirements to mitigate overheating in residential buildings . A start was made on this last year with the changes to building regs and parts F , L and O .
Following public consultation , a Notional Building Specification has been developed which states that window U-values will need to be 0.8 ( W / m2 . K ) down from 1.2 ( W / m2 . K ) currently . Doors will need to be 1.0 ( W / m2 . K ) from 1.2 ( W / m2 . K ) ( where more than 60 % glazed )
This is likely to lead to triple glazing becoming the norm in most windows for new buildings or retro fits that want to achieve the highest performance .
What is triple glazing ? Very simply , triple glazing is an extra pane of glass added to the two used in double glazing but the benefits can be great . Up to now , many of our clients have opted for triple glazing in areas where they require high acoustic performance , with this comes much better thermal performance , saving money on fuel bills .
What are the advantages of triple glazing ?
• Excellent thermal performance that meets the new Future Homes Standard , will save you money on heating
• Great acoustic performance - ideal for blocking out noisy roads , aircraft noise etc
• Better security - thicker units are harder to break
• Can help to reduce condensation
They used to have unsightly plugs where the air was extracted but the latest technology means this is no longer the case . Ultra thin from as little as 7.7mm compared to 44mm for triple glazing , it ' s great for listed historic properties or new builds looking for a sleek slimmer aesthetic .
What are the benefits of vacuum glazing ?
• 3-4 times thinner than triple glazing , looks more like single glazing
• Same thermal performance as triple glazing . Fineo states 0.7 W /( m2K ) which is better than the target the Government is aiming for in the Future Homes standard .
• Lasts longer - because it doesn ' t have gas between the panes which can leak over time
• Better solar gain - allows more sun heat into the room helping reduce energy bills
• Much lighter than triple glazing
• 15 % more light is allowed into the room compared with triple glazing
• Environmentally better - much lighter saving on transport and less product used plus last longer so less need to replace
• Great acoustic performance
• Better aesthetically especially for historic properties , listed properties and modern contemporary builds that want to avoid heavy frames and fixings
• Easier to install
What are the disadvantages of vacuum glazing ?
• Typically it is the most expensive option compared with double and triple glazing , this is thought to be due to there being no UK manufacturers making it and the inherent cost of the materials , some use silver for example
• Low impact resistance - where micro pillars are used it can put high stress on the glass .
How much does vacuum glazing cost ? Vacuum glazing can cost up to 60 % more than double glazing and around 35 % more than triple glazing *. * Prices may vary depending on size and spec .
What are the disadvantages of triple glazing ?
• It costs more than double glazing but usually not as much as vacuum glazing .
• The windows are heavy which means they require chunkier frames and stronger fixings , all of which increase the price further .
• Aesthetically , some people dislike the look of the triple glazed windows because they aren ' t as sleek as single or double glazed ones .
• Reduces the amount of heat from the sun limiting thermal gain . Harnessing solar energy is something homeowners have done for centuries and this is harder with triple glazed units .
So which should builders and architects choose from 2025 ? Inevitably , it will end up coming down to price in most cases . We predict that most people will opt for triple glazing unless something drastic happens to the price of vacuum glazing , which may happen as the product becomes more popular and their production efficiencies improve . However , for anyone looking to balance the new regulations with heritage detailing , vacuum glass is the option that makes this possible .
“ We are getting more and more enquiries about vacuum glass from architects and specifiers who like it for its performance and great aesthetic qualities , but often value engineering means they have to fall back on triple glazing .”
What is vacuum glazing ? Vacuum glazing takes two pieces of glass with a tiny gap ( 0.1mm in the case of Fineo ) and removes the air to create a vacuum .
Tom Wright , MD , George Barnsdale
www . georgebarnsdale . co . uk
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