The History and Science of Reflective Foil Insulation
When considering the science of reflective foils, one has to understand that the concept is a commercial spin off from the NASA Apollo Space program. Reflective foil coverings were used to create a radiant barrier for both the spacecraft and space suits, reflecting the intense heat of the sun away from the astronauts by day and reflecting internal heat back inside the capsule or space suit at night for warmth.
Reflective Materials, born out of this superior technology present an excellent solution to building insulation applications of all types.
This intelligent product is effective, due to the inherent nature of foils which has an extremely high reflectivity of 97% and very low emissivity of 3% for re-radiation. Aluminium Foil Insulation with adjoining airspaces provides a permanent and continuous barrier to heat radiation.
Energy Efficiency in the building envelope will become the rule rather than the exception. There is absolutely no doubt that buildings, both new and old will have to be insulated. Insulation is the here and now and the future.
It was therefore of great concern to some of the Reflective foil manufacturers that when SANS 204 energy efficiency standards were published, very little positive information was present on reflective foils.
In fact it would appear, that professional and public awareness regarding the thermal superiority of foils as insulation or radiant heat barriers is inadequate. It is also apparent that the perceived negatives that are attributed to foils are largely ignored in other insulation types.
What really riles this author is that all products, bulk, reflective foils and boards are affected by the same potential problems experienced in both the roof and ceiling. Dust settlement and water vapour are two of the evils that continue to raise their heads and, wrongly so seem to be only attributed to the use of reflective foils. What absolute nonsense. It does not even bear discussion as it is too unreasonable to consider. It is bad business practice to allow one insulation type to assume that they are better than another because they are not affected by dust or moisture.
The purpose of this document is not to defend or highlight how moisture renders bulk or board products ineffective or how dust may negatively affect thermal performance of foils but to emphasize the fact that all insulation types have their own set of problems and none are exempt from the realities of the conditions that they would be subjected to in a ceiling or roof application with regard to these issues,. It is more important to point out the responsibilities of all parties concerned in ensuring that the correct product, in the correct application, applied to a building in a specific zone or region as per the zone map provided in SANS 204, will do the work required. No matter how unique a building design is, the basic principles of best practice in design should be applied. Orientation, ventilation, shading provided by shuttering over windows and or leafy green vegetation during the summer which loses its leaves during the winter coupled with the correct use of insulation for the application, will advance the progress toward more energy efficient buildings.
Reflective Foil products should be passionately defended, and that is our endeavor. This dynamic product should not only appeal to the creative, artistic nature of the architect; he or she can rest assured that there is absolutely nothing that reflective foils can’t achieve. Architects and their ability to create practical performance and beauty from brick and mortar combined with the correct finishes should be intrigued by reflective foil. This merger of science and art is captivating.
The Reflective Foil manufacturers in association with TIASA are developing a handbook which will explore and expound the merits and uses of foil insulation in all types of applications in building design, our undertaking is to present a document which will arm professionals with the tools they need to enable them to elevate the use of reflective insulation with confidence.
The unique abilities of this product applied within a system, taking into account the outer air coefficient, inside air coefficient and the individual R values of the materials within the system, whether roofs, walls, or floors, cleverly coupled with the reflectivity and emissivity of foil, used singularly or in conjunction with other products, or even assembled with more than one foil layer and related air gaps, can provide the “R” Value interventions and Noise Reduction Coefficients which are acceptable to building efficiency.
It also stands to reason that in our particular climate, protecting our buildings from downward heat, especially radiant heat is something which requires greater consideration. Research shows without a doubt that temperatures in our country are climbing, we are definitely experiencing hotter summers and our winters in many instances are not as extreme.
The Mail and Guardian quotes Leonie Joubert author of ‘South Africa’s Changing Climate’ as predicting that summer temperatures rising by between 0.5 degrees Celsius and 4 degrees Celsius over the next few decades.
The Council for Scientific and Industrial Research (CSIR) also released a report on how climate change is affecting Durban, and predict that their maximum temperature will rise by 3 degrees Celsius and minimum temperatures will rise by about 4 degrees by the year 2070.
At a conference on “Green buildings” that was held recently, it was said that in the next 50 years most of the buildings that are around today and those that are being built now will still be standing. This is the heritage we are leaving for future generations. Is it not our responsibility to our children and their children to equip our buildings for the type of future we are expecting? Of course it is – it makes sense. In areas that are prone to earthquakes, buildings are designed to absorb shockwaves rather than crumble during them; in our beautiful sunny country shouldn’t we be designing and insulating our buildings to take the kind of heat load that they will be subjected to in the next few decades?
Reflective foil is intelligent, scientific and extremely futuristic. It is very well suited to the extremely hot conditions we experience now and certainly will be experiencing in the future, reflective foils can also be of benefit in winter conditions if correctly installed, not to mention the fact that they do have the ability of enhancing the performance of other insulation types.
My appeal to the professionals is to give reflective foil an opportunity to prove its value in your design.