How does Low-E Insulation compare?
There are a lot of questions and misunderstanding online about foil insulation, how it works and how foil insulations compare to each other and ‘traditional’ insulation. This blog has been put together to answer some of the most basic questions about Low-E Reflective insulation and foil insulation in general.
If you want to know more about Low-E Insulation and how it works you can read our blog opposite.
Foil insulation is a very simple idea; use pure aluminium to reflect heat back to the heat source. So, why do so many companies get it wrong?
It is possible to reflect heat with a single layer of aluminium, that bit is easy! The problem is, when you do that, it creates an increased risk of condensation forming on the surface or the product.
So, the obvious answer is to add an additional separating layer to reduce the risk condensation and create a thermal break. Different companies have tried to do this several ways, using various materials and methods. The problem is the materials and methods of production tend to create additional problem which then need to be dealt with.
Some of the most common questions we get asked are;
- What is the difference between Low-E Reflective Insulation and other ‘foil’ Insulations?
- What is the difference between Aluminium and Mylar?
- How is Low-E Reflective Insulation different to traditional insulation?
Other types of ‘foil’ insulations
Bubble Wraps and Single Layers
Bubble Wraps and Single layered products have an increased the risk of condensation forming on or in the product
Glued and laminate products contribute to fire spread and the glues break down over time and the products de-laminate, especially when subjected to heat and cold the way insulation is.
The obvious problem with a fibrous material is that it can absorb moisture. However, products with fibrous cores usually have multiple layers and are usually referred to as Multi-Foil Insulations and these can have a whole host of problems.
Aluminium is an electrical conductor. Please use caution when working around electrical sources, including overhead power lines.
Low-E should be stored on a flat dry surface in its bag, out of direct sunlight, until it is ready for installation.
Multi Foil Insulation
Multi Foil Insulation is a multi-layered product that can often have lots (and lots, and lots, and lots) of layers. This tends to make them thick and heavy which (in my opinion) defeats the purpose of a thin reflective insulation. It also makes them hard to work with, but the problems don’t end there. Multi Foil Insulation is a multi-layered product that can often have lots (and lots, and lots, and lots) of layers. This tends to make them thick and heavy which (in my opinion) defeats the purpose of a thin reflective insulation. It also makes them hard to work with, but the problems don’t end there.
What is the difference between Low-E Reflective Insulation and other ‘foil’ Insulations?
Most of the foil insulations on the market tend to have poor fire ratings or no fire testing at all, which means they are unsuitable for use in a wide range of applications. These products need to be installed behind plasterboard to comply with fire regulations. But that is little help if a fire starts in the wall cavity.
Poor fire ratings
Multi-foil insulations are not used or found in countries where regulations and foil insulation used is widely understood. In the USA for example, foil insulation has been used for over 30 years but multi-foil insulation is not sold there and cannot be used due to its lack of compliance and failure to meet basic Fire Safety Standards.
Any product with a fibrous core risks moisture absorption. When that product has a layer of aluminium (or mylar) as an outer layer, you risk the moisture travelling through the core of the product, the product sweeting, and over the course of time, corroding and delaminating.
Thick and Bulky
Some of these multi-foil products have more than 15 layers. and can measure anything from 35mm – 75mm thick. This completely defeats the idea of a thin efficient reflective insulation.
Companies making these products are making bulk insulation because they are using mylar and don’t understand foil insulation so they are trying to be all things to all people.
Hard to install
Anyone who has handled a multi foil insulation will know, their multiple layers make them heavy, very difficult to cut, and even harder to work with. They are very labour intensive (and therefore expensive) to install.
Larger Battens Needed
These thick and bulky multi foil products require thicker battens, longer screws and fixings but a lot of multi foil Insulation companies tell customers their products can be installed 20mm or 25mm battens.
The problem is, Multi Foil products can be anything from 35mm – 75mm thick. Manufactures fail to explain that creating a 20mm airspace beside a product would require a minimum 47mm – 97mm batten (as long as you also maintain an airspace above the insulation).
Do not meet claimed u-values
If any foil insulation is installed with a smaller counter batten than required, and does not have an airspace beside the foil surface, it will not achieve the claimed (or required) U-value for that application.
What is the difference between Aluminium and Mylar?
A lot of ‘foil’ insulation products are made from a product called mylar instead of aluminium. Only aluminium has a natural low emissivity value. Mylar is much cheaper to produce. It is a plastic laminated or painted with an aluminium coating. Companies that use Mylar claim it to be a low emissivity product. But Mylar, while it looks ‘shiny’ and is good at reflecting light, it does not reflect heat in the same way as aluminium.
You tend to see mylar used in a lot of single use applications. (Emergency foil blankets, packets of crisps and Kit-Kats wrappers). It might be good at keeping food fresh but it is not something you want used in an insulation material.
These coated plastics crack, chip and peel and de-laminate within a very short space of time (especially when it is exposed to heat and cold as often as insulation is), you end up with the emissivity value of plastic rather than aluminium.
Here you can see a comparison between Low-E Insulation a number of other foil insulation on sale today.
How is Low-E different to traditional insulation?
Reflective insulation is not a new idea and it is not supposed to replace all other insulation materials.
It is designed to compliant an insulation system and to address issues which are not addressed by traditional insulation (Radiant heat, Air-tightness, Moisture control)
For years people have people have thought that to insulate better, they should simply add more and more material, believing that the thicker the insulation, the better it works.
However, that doesn’t really solve the problem. Very high R-values don’t stop heat transfer, they only slow it down. You cannot ignore the need for good U-values, but by addressing the U-values alone, a large percentage of heat transfer is being ignored.
All insulation materials have drawbacks, so using more and more of the same material may only compound a problem.
Just like any foil insulation with a fibrous core, any ‘traditional’ fibrous insulations risk the same way, however moisture can effect traditional insulations in an even greater way. They become compressed over time and lose their ability to insulate.
You can read more about moisture control in our blog Moisture Control – Why is it important?
Rigid Foam Insulation
Bulky – Rigid boards are extremely popular and there is no question that they are good insulators. However due to their rigid design they are extremely bulky which means there is a huge amount of space required to transport and store them.
Hard to Handle – Rigid boards are also very cumbersome to handle and install. They can be difficult to cut and produce a lot of waste material.
Environmental Impact – There has been worldwide criticism in recent years of the environmental impact of these types of insulation. Although designed to last 20+ years, once they come to the end of their life cycle, a lot of rigid foams cannot be recycled, incinerated, or put into landfill. The waste needs to be kept dry stored above ground. This is going to become a massive environmental issue over the next 20+ years. There are increasing reports of these products being cleaned out of our oceans and off our beaches.
Low-E Insulation is different!
Low-E is not a multi-foil insulation and it does not have any of these multi-foil drawbacks!! We pride ourselves of having one of the best fire ratings on the market. We achieve a Class 1 (BS 476) and we have performed fire tests all over the world to the strictest standards. ASTM E84 and E603-77, AS NZS 1530.3
If you have read our blog – How does Low-E Insulation work? you will understand how foil insulation works, and you will understand that surface material is the most important part of a reflective insulation. The core is supplementary. So, if the work is done by the surface, why would you manufacturer a product thicker than it needs to be?
You would be much better off using a thinner foil insulation along with a thicker secondary insulation that is designed to be bulky and address the issues that a bulk insulation needs to address.
It would also be quicker and cheaper to install!
A Modern Solution – “People don’t understand, it doesn’t just save space in the building. We can design thinner wall and roof profiles, this means we can use smaller timbers, shorter nails and screws. The knock-on effect of utilising Low-E Insulation in buildings is huge”
– Anthony Brown – Director at Dwell Design Architects
Rigid Foam Insulation
Low-E Insulation is arguably one of the best performing insulations on the market. It has huge environmental benefits over other insulation materials with the added advantage of occupying less space. Low-E is only 5.5mm thick. Occupying less space results in more internal floor space but Low-E does not just benefit the finished building.
Transport and Storage
Using Low-E Insulation means there is much less material to transport on the roads, there is less material for the builder’s merchants to handle and deliver to site. There is less material on site to handle. It reduces install time; it reduces labour cost. The impact it massive.
Just look at the difference between 60m2 of Low-E Insulation and long side a pallet containing 60m2 of traditional fibrous insulation!
‘Traditional’ insulations can have a negative effect on indoor air quality, due to airborne fibres that can stick to your skin or get in your eyes, some are even classed as carcinogens and are produced using toxic blowing agents.
Where using such traditional materials, it is always a good idea to combine a barrier material such as Low-E which can prolong the life expectancy of an insulation system and stop airborne fibre and gases from entering internal spaces. It will also work to stop the penetration of dust, pollen and other such allergens, making it ideally suited for uses in homes, offices, schools and other health sensitive applications.
Using Low-E Insulation as part of a combination system alongside a fibrous insulation protect from absorption, prolonging the life of the insulation system.
Modern design and modern buildings require modern thinking. Using a combination of materials designed to address specific issues should be best practice and the goal of all holistic designers and thinkers.