I’m not sure whether it’s preferable to be stifling hot in summer or freezing cold in winter. But then why should you have to choose? If you make intelligent choices, you’ll be cool in summer and snug in winter. You’ll have the best of both worlds, all year round.
If you can effectively block out excess heat from your home in summer (and you can, very easily) you’ll be a whole lot more comfortable. If you prevent heat loss in winter, you will not only be more comfortable at home when it’s icy outside, but you will also be making a giant step towards conserving energy.
While I have to admit that I’m really more concerned about insulation that will either keep heat in or out of the house, I mention ventilation because the movement of air is also important. It isn’t just that we all need fresh, healthy air to breathe; it’s also vital to have air flowing through our homes. But first let’s focus on insulation.
To get this right, you need to understand a bit about the 3 main ways in which energy (in the form of heat) moves or is transferred:
1. conduction – when heat is transferred quickly by contact through solids (and to a lesser extent liquids and gases);
2. convection – when heat is transferred through liquids and gases (for example in the form of wind); and
3. radiation – which doesn’t rely on any other medium to transfer the heat.
Now the heat from the sun reaches earth as radiant heat, and it is this heat that you are looking to escape from when you look for shade in the garden on an ultra-sunny day. When we insulate our homes, we minimize all this stuff by using double glazing, carpets on floors, cavity wall and timber frame insulation, and attic insulation.
Now, here’s an open secret. Your attic insulation isn’t going to be effective unless you get it right. Right! I say this because people are forever asking me whether to use traditional attic insulation materials – you know, the fiberglass and cellulose types – or whether to go for some type of radiant barrier.
I have two standard answers to these questions that don’t have anything to do with the type or size of house you want to insulate.
1. If you want to be cool in summer and warm in winter, you need to combine good quality fiberglass or cellulose attic insulation with a top quality radiant barrier.
2. “Some type” of radiant barrier isn’t going to cut it. You need the best and it must be double-sided.
Standard attic insulation materials reduce conductive heat flow. A radiant barrier isn’t meant to replace this type of insulation. Rather, it improves the way it works. Why? Well, simply because materials like cellulose and fiberglass also hold heat. That’s really cool – I mean hot – in winter. But in summer it can be hell.