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Heat Mirror Film vs Triple Glazing – Our Verdict
With energy prices rising, carbon legislation changing, and homeowners becoming more environment-savvy; the pressure is on to find ways of minimising the heat lost through glass. Triple glazing is currently being heavily promoted and heralded as the future by various glass manufacturers; whilst lightweight alternative Heat Mirror Film has still to make a big impact in the UK market. Cantifix installs both products – but here’s our take on why we are backing Heat Mirror Film as the ideal solution to heat loss through glass…
What Is Heat Mirror Film?
We have been talking about Heat Mirror Film for a while now, but just in case you haven’t heard about it, here are the basics. Heat Mirror Film was developed by the MIT (Massachusetts Institute of Technology) in 1979, as the result of a USA government funded research programme; and released commercially by Southwall Technologies in 1980. It is a polyester film with a transparent, multi-layer metallic coating that transmits light, but reflects long-wave infrared energy. This coating is applied by the electrical process ‘magnetron sputtering’. Although there are a subset of films suitable for different aspects and climates, the overall principle is very simple—the tiny particles of metal within the film reflect any radiation (heat) back to where it came from - so in the winter it reflects heat back into the home, keeping it warm and minimising heating bills. In the summer it reflects heat back into the environment - stopping it from overheating inside.
What About The Figures?
A standard Cantifix double-glazed unit with a single sheet of Heat Mirror Film suspended in the cavity will achieve average u-values of 0.6 w/m2/k, whilst the same composition with two sheets of Heat Mirror Film will achieve an average u-value of 0.3 w/m2/k. This is well below the PassivHaus requirement of 0.8 w/m2/k—and easily equivalent to what is achievable with triple glazing. As well as blocking heat, the film also blocks more than99.5% of damaging UV rays – protecting furnishings from fading and degradation caused by the sun; and reduces sound transfer by 2-3 dB (compared to a standard unit) - creating a quieter internal environment. The benefits delivered by Heat Mirror Film are exactly the same whether it is installed vertically or horizontally, and the product can be combined with any gas infill or coated glass.
How Does It Compare To Triple Glazing?
Whilst triple glazing might boast similar u-values to those achievable with Heat Mirror Film, these come at a very heavy price—around 10kg per square metre of glazing. In the case of structural glazing this means that a costly crane would be required far more frequently, and the logistics of installation could become difficult. Even for simple windows and doors, the extra weight of each glazed unit would make installation trickier, and potentially compromise the ease of operation, as well as the service life of hinges and fittings. In products such as folding or sliding doors, this issue can be solved by using a larger number of smaller panels—but most homeowners are keen to minimise framing, not increase it. In terms of financial cost; both triple glazing and Heat Mirror Film offer substantial savings in energy bills, however triple glazing is far more expensive—both in terms of procurement and installation. Homeowners can expect to pay around £150 extra per square metre for Heat Mirror Film.
But Is It Reliable?
Recently we have picked up on a few concerns around the industry about the reliability and longevity of Heat Mirror Film. The product has been around for over 30 years, and was recognized as one of the Top 100 Inventions of the Millennium by Popular Science magazine in 2000. Over 3 million square metres of Heat Mirror Film have already been installed, and there are many long-standing examples of its durability – including Werner Sobek’s ‘Low Energy House’ which was completed 12 years ago, and uses the film in each of its 4 glass walls.
If any further reassurance were required that Heat Mirror Film is the ideal energy efficient glazing product, the retrofit recently completed on the Empire State Building is a great example. Every single one of the 6500 windows in the building was retrofitted with Heat Mirror Film, as part of a program designed to reduce the building’s energy usage by 38% per year. The updated windows are expected to save a massive $400,000 in energy bills per year. Heat Mirror Film is durable, scalable, proven, and provides unmatched insulating performance, and its use in the Empire State Building project is perfect validation of this.
Cantifix Director Charlie Sharman concludes with his thoughts on the comparison; ‘We are all aware that there is an ecological price to pay for our high level of energy use in our living and working environments. When you combine this with the human need for daylight it was obvious to Cantifix that a solution had to be found to reduce energy consumption without compromising light transmittance. The cost and weight of a double glazed panel incorporating Heat Mirror Film, compared to a triple glazed unit, makes the decision an easy one to make. I will not be surprised if Heat Mirror Film becomes the standard specification for all glazing projects within the next 5 years.’
- Visit the Heat Mirror Film product page, or look at a project involving Heat Mirror Film.
- Request a copy of Southwall’s Heat Mirror Film Durability Statement.
We would love to hear your thoughts on this topic and answer any further questions you may have—just email innovation@cantifix.co.uk.
Please note: Cantifix will happily supply and install triple glazing if this is the preference of the customer.
Cantifix to host CPD brunch following success at RIBA’s Guerrilla Tactics
Cantifix has recently become a CPD provider, lecturing on 'Glass as a Construction Material'.
Director Charlie Sharman presented the seminar at RIBA's Guerrilla Tactics CPD event in November 2011, which was themed around practice specialism. Feedback was excellent, with one delegate commenting, 'the outstanding seminars included a top subcontractor at the cutting edge of its area (Cantifix)'.
Following the success of this event, Cantifix has decided to host a CPD brunch at its north London showroom at 10am on 20th March 2012.
The hour-long session will provide a wealth of expert glazing knowledge - with the seminar running right through from the history of glass in construction, to the latest technological advances in glass and glazing.
Featured topics include structural glazing, joining old to new, u-values, photovoltaics, nanogel, prismatic glass and UV bonding. Refreshments will be provided, and there will be time to ask any questions you may have - as well as see, touch and operate a range of products in the newly refurbished showroom.
Cantifix plans to host further CPD events throughout 2012. Feedback from attendees will help us to shape these events and make them as beneficial as possible!
To register for the CPD brunch on 20th March 2012, please email innovation@cantifix.co.uk, simply including your name and practice.
Cantifix celebrate 25 years of glazing innovation with new showroom launch and Expo - November 2011
Cantifix celebrated 25 years in business on 17 November 2011 with an Innovation Expo at their newly refurbished showroom in north London.
The Innovation Expo brought together architects, contractors and clients to visit the new showroom, which contains over 30 premium glazing ideas. Featured products included energy-saving glazing such as Heat Mirror Film and Nanogel, and specialist glazing such as fire rated glass floors and UV bonded corners. Visitors were also among the first to see two new products in action - Slideglaze, a massive remote controlled sliding glass roof, and E-Slide, a remote controlled sliding door system.
Expo highlights included a dramatic live demonstration of the difference that fire rated glass can make - and a panel discussion with the UK’s leading glazing experts, including Neil Sharda from Sharda Glass, Peter Anderson from CS3 Securiglass, Kurt Russell from Southwall Technologies and Andrea Marston from AGC Glass.
Andrea Marston, of AGC Glass said "I don't know of any other building material that has the versatility of glass. We're always looking for something to new develop, and that can vary from the aesthetic through to performance based initiatives and protoypes."
The new showroom is open to all by appointment and provides plenty of inspiration for both domestic and commercial building projects, and a space for architects and contractors to bring their clients and discuss glazing options.
Call us on 020 8203 6203 to make an appointment to visit the showroom.
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