New Challenges for R&D While Developing Polyamide Thermal Break Systems: U Value Calculations Using Radiosity Method

By Bogdan Grebenyuk, Product Manager at Thermevo
on Nov 29, 2017
For a U value thermal break to be effective, it must be measured optimally, such as with the radiosity method.
Any new standard of calculation is bound to create difficulties for research and development departments (R and D) no matter which sector of engineering they happen to work in. Of course, in the aluminium windows industry, we have been long used to producing thermal insulation figures where polyamide insulating bars have been fitted, with usually improved results year on year. Yes, this has been down to the quality of the sort of polyamide thermal break technologies being used, but it has also come down to the way many in the industry have become skilled with developing products that perform well, producing attractive U values under the standards as they have existed. However, under the new regulations, as laid out in BS EN ISO 10077-2:2012, the new radiosity method of calculation must be applied where the thermal performance of an aluminium façade or an aluminium door system is to be accurately predicted. The new method may create a series of challenges for many research engineers, but it could lead to reduced energy wastage from passive house aluminium windows down the line, so we should all embrace the change.

To improve is to change; to be perfect is to change often.
Winston Churchill

Will the Radiosity Method Really Make a to U Value Thermal Break Development?

In particular cases, the difference between the new and the existing version of the calculation standard can be surprisingly significant, in my experience. For all researchers and developers, whether we have been working on ABS thermal break inclusions, a new PUR-Foam profile or glass fiber reinforced polyamide insulation, the shift may make what was once a perfectly good system now appear weaker. Of course, there are always winners and loser with any systemic change, but the European aluminium window industry ought to remember that National Fenestration Rating Council has preferred the radiosity methodology for US engineers for years. By coming into a closer alignment with North American window development, we should be able to demonstrate just how strong R and D is in Europe, rather than exposing any problem areas. This is likely to be particularly so in research fields such as thermal break with flag or pad technology.

Radiosity Versus Other Methodologies

I know that many industry professionals have expressed preferences for other methods of thermal calculation than the radiosity one now chosen as the standard to which we must all comply. If you look at research by Korean academics, there are obvious differences in outcomes when radiosity is used as the preferred method. However, it is important that, as an industry, we must embrace radiosity and move forward with it. After all, the standard comes into force in November 2016, so complying with it will have to be the norm, no matter what that means for our future thermal results when derived from software. If we need to invest time and effort improving our products to meet the new standard, then so be it. It is only our clients who we are ultimately serving, after all. And don't they deserve the best windows we can design construct?
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