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Last edited 12 Jul 2022
Glass wool v reflective foil insulation
 Selecting insulation
Making the correct choice of insulation is never easy and straightforward, as many factors need to be considered. All available insulation products have their advantages and disadvantages, depending on the area in which they are installed, external factors, climatic zones, humidity levels, accessibility of the space to be insulated, etc.
The first thing to stress is that there is no "good" or "bad" insulation, as each product has its advantages and disadvantages compared to others, but a general comparative review can help understand different materials. This article will explain how to choose between glass wool and reflective foil insulation.
 Glass wool Insulation
Glass fibre (or glass wool) is one of the world's most popular insulation materials and one of the most widely used products in the world. Its easy installation, as well as its versatility (as it can be installed in almost any space), are probably the reasons for this. It is made from fine glass fibres, which are bonded by an adhesive added during the manufacturing process, and is usually packaged in rolls or blankets so that it can be installed almost anywhere - it can be rolled between roof or floor joints, inside walls or on ceilings.
 Reflective foil insulation
Reflective foil insulation, on the other hand, is becoming increasingly popular because of its ability to reduce radiant heat. The reason why reflective foil insulation can often be used in roofs and attic spaces is that it reflects radiant heat from the sun and is therefore an excellent insulating material. It usually comes in the form of sheets or rolls of foil (aluminium foil is the most popular type of foil) which can be easily wrapped around joints or pipes.
To understand the basic difference between these two insulation types, apart from their softness, you need to understand that heat is transferred in three basic ways, namely convection, conduction and radiation. Glass wool insulation is designed to reduce and stop convective and conductive heat transfer, while its counterpart is primarily used to stop radiant heat transfer.
Basically, radiant heat transfer can be stopped either by absorption (certain materials will absorb heat) or by reflection (by reflecting sunlight, for example, rather than letting them pass through).
As the name suggests, reflective foil insulation reflects radiant heat, which is important as 70% of heat loss and gain in a building envelope comes from radiant heat transfer. This makes this insulation very useful in both winter and summer. On the other hand, glass wool insulation is more effective in terms of convective and conductive heat transfer, which is why it is most commonly used to insulate internal walls.
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