News: House in sheep’s clothing
I used to feel sorry for sheep standing in the blinding heat of the Australian outback – imagine wearing a thick jumper all day when it is over 35oC! Now I suspect they actually feel sorry for me.
There are over a billion sheep living on this planet today, made up of hundreds of different breeds. They all descended from wild flocks living in the hot, dry lands of the Middle East over 10,000 years ago. If sheep came from the desert, why would they need to grow thick, woollen coats?
For one thing, the desert can get quite cold at night. So sheep need a material that can keep them toasty warm when it’s cold. But they also need to keep cool when the temperature rises. Importantly, they can’t waste a lot of energy on warming up and cooling down. Fortunately, wool is a great insulator.
Heat is the energy in jiggling particles. For it to spread, particles need to bump one another. Just like a crowded train, it’s easy when the particles are close together, such as in solids. But in gases, they are spread out, making it hard for heat to move. Insulators such as wool trap pockets of air that slow the movement of heat.
Our houses also need to keep cool when it’s hot and warm when it’s not. Unlike the savvy sheep, we tend to use energy to produce more heat when we’re cold and then plug in an air conditioner to cool down in the warmer months.
Putting a coat on a building might seem like a silly idea at first, but it’s more common than you might think. Hidden by the walls and ceilings are panels of fibre designed to slow the spread of heat, much like fuzzy underwear for your home. Without it, more energy is required to keep your rooms cosy.
Some insulation products are actually made out of wool, but there are lots of other kinds too. When you think it can reduce how much we spend on power bills each year, not to mention reduce greenhouse gas emissions, it makes sense for your home to be clothed.
Just don’t make it too comfortable. Next thing you know, you might have a sheep knocking at your front door.