Natural Home Insulation Materials
by LJ Martin
Carbon dioxide emissions due to heating your home are a major part of your carbon footprint, and can add up to at least a ton of CO2 each year, so good insulation is crucial. In this article, we will look at some of the natural home insulation materials that have come onto the market. As these are made of natural materials, their manufacture produces less CO2 than that of traditional home insulation, which further reduces your carbon footprint.
How does insulation work?
Insulation works by trapping tiny pockets of air. It is these air gaps which actually prevent heat from escaping. A large airspace cannot be used because convection currents would arise, which would circulate the air between the warm interior of the house and the cold exterior. Trapping the air in small pockets serves to stop the air circulating, therefore producing a far better insulating effect.
Now we know what an insulating material has to do, let's look at some of the natural materials which are now available ready prepared for home insulation.
People have known for thousands of years that wearing sheep's wool is a great way to keep warm. It is only recently that home insulation made from sheep's wool has been available commercially. This takes the form of a thick felt-like material (as pictured), which comes in rolls which are the right width to fit between the wooden joists in your home's loft or walls. The manufacture of sheep's wool insulation consumes far less CO2 than that of traditional glass wool, and also has a very interesting feature. Sheep's wool absorbs moisture without losing its insulating effects, and this lets it regulate temperature to some extent. When it absorbs moisture, it gives off heat, and when it releases moisture, it cools down. This helps to regulate the temperature of the house. Sheep's wool is also naturally fire retardant, as it will singe but not sustain a flame. Obviously, it is non-toxic and safe to handle (or we wouldn't make clothes out of it!) The only real downside of sheep's wool insulation is that it is much more expensive than man-made materials, although it will pay for itself after a few years of reduced heating bills.
Insulation can be made out of natural plant fibres such as cotton, hemp and flax. Again, these produce far less CO2 in their manufacture than man-made fibres, and have similar insulating properties. They are able to regulate moisture, although to a lesser extent than sheep's wool. Plant fibres are also non-toxic and safe to handle, and are available in rolls just like conventional insulating materials. They are generally treated with natural chemicals such as borax to make them fire retardant, and to prevent them from rotting. Plant fibre insulation is cheaper than sheep's wool, but more expensive than glass wool.
Loose fill recycled newspaper
Unlike sheep's wool and plant fibres, which come in large rolls, loose fill insulation consists of small particles which are simply poured into the space that needs to be insulated. The most common natural loose-fill insulation material is recycled newspaper, shredded into tiny scraps. This has been treated to make it fire retardant, which is so effective that it cannot be lit even with a blow torch. Loose fill insulation is fairly cheap, but the downside is that it is more messy to use than roll insulation. It can be bought in sacks for DIY use, and these sacks are simply tipped into the space between joists in the loft. Professionals use machines to lay loose fill insulation by blowing it out of a hose. Obviously, the loose insulation will easily be disturbed, so it is best used in walls or loft spaces where access is not required on a regular basis.
It is vital that your home is insulated to keep the heat in, reducing your heating bills and carbon footprint. Any home without loft insulation should have this installed as soon as possible, as it will pay for itself within a few years. If there is a thin layer of loft insulation, this should be topped up to the level recommended by your local authority. While man-made fibres such as glass wool are usually the cheapest way to insulate a house, there are now highly effective natural fibres which can do the job. Their manufacture releases less CO2 than that of man-made insulation, and therefore reduces your carbon footprint.
Sheep's wool is the "Rolls-Royce" of natural insulating materials. It is expensive, but gives excellent insulation and also has the useful property of regulating temperature as it absorbs and releases moisture. Plant fibres such as cotton, hemp and flax are cheaper, but very nearly as good. In suitable homes, shredded, recycled newspaper can be used as a cheap, loose fill insulation. All of these have similar insulating properties to the man-made materials that they replace, but this is not the most important issue. Depending on the insulating value, a thinner or thicker layer of insulation can be used, to the home will have exactly the same amount of insulation regardless of which material is chosen. The main reason to use natural home insulation is due to the reduced CO2 emissions in its manufacture.