With our climate changing and energy costs constantly rising, it makes enormous sense to insulate, regardless of your home’s vintage.
Whether you’re heating or cooling your home, insulation makes a huge difference, not only in your energy costs, but in how your home feels. Well-insulated structures keep temperatures more constant, feel less drafty, conduct much less noise, and just generally give occupants the sense of a better quality, more tightly-constructed home.
In this article, we’ll discuss the relative merits of different types of insulation, and try to give you a good background in what insulates best. We’ll look at the insulation materials homes typically utilize today, and review their effectiveness, temperature limits and geographical usability. We’ll check out the newest generation of green insulation materials, and explore how you can insulate your home cheaply, efficiently and easily.
First--What’s an R-Value?
Insulation materials are rated by their R-value—which is a measure of its thermal resistance. All materials conduct heat, some more than others, and a high R-value means that particular insulation material and thickness conducts less heat. The higher the R-value, in other words, the higher the insulating effectiveness. Building codes in many parts of the world, and all across North America, increasingly call for minimum R-value insulation levels in roofs and ceilings.
The Science of Warm—How Insulation Materials Perform
Just about any material can insulate. Builders, since the beginnings of civilization, have used everything from dirt to sand to straw to cow dung (which I wouldn’t recommend). As more advanced building techniques came along, people used stone, brick, mud or adobe walls, some two or three feet thick, to insulate everything from huts to castles. Those extremely thick solid walls probably had very high R-values, but just aren’t practical now, unless you’re a king or a queen.
Today, most traditional almost all new homes have wood frame construction with studs that separate the outer wall of the house from its inner walls. The space in between, determined by the width of the framing studs, usually gets filled with fiberglass batt insulation, rock wool or mineral wool insulation, one of the rigid polystyrene insulation products, or some form of loose-fill, blown-in insulation like cellulose or fiberglass.
Typically, most building codes (except in very cold regions) call for R-13 insulation ratings in the walls of houses. Since heat rises, the thinking used to go, we should insulate roofs and attics more fully than walls, usually with a minimum of R-30 insulation. But most homebuilders and many energy and environmental experts now realize that the old R-13 wall and R-30 ceiling insulation standard doesn’t make for a very efficient or well-insulated home, especially in particularly hot or cold climates. Instead, many walls are now insulated to R-30 or R-40 levels, and roofs and ceilings to R-60.
Insulation and the Home Energy Audit
If you’ve read this far, I’ll assume that your home doesn’t have new, energy-efficient insulation. If that’s the case, I’d be willing to bet that you can reduce your energy bills, sometimes dramatically, by adding insulation where it counts the most. In fact, adding insulation to newer houses can pay off in a few years—so you can imagine how much you could save by insulating an older home.
Many companies can evaluate your home’s insulation by doing an assessment, also known as a home energy audit. They can tell you, after an inspection, where your home is insulated and where it isn’t, what type of insulation the builder used, and then evaluate the R-values of that insulation.
If you want to conduct your own energy and insulation audit, just ask the builder for your home’s construction information—or if that’s not possible, unscrew a wall plate from an electrical switch or outlet, which will let you measure the thickness of your home’s insulation. (Be careful not to touch any exposed electrical contacts on the outlet or switch while you’re measuring.) Next, take a look in your attic and measure the thickness of the insulation there. Then go to this site, which will help you conduct a thorough DIY assessment.
One more step: to determine the level of insulation recommended for your area, and the rate of return on your investment in new insulation, just enter your zip code into this Department of Energy calculator.
Green Insulation Materials
Many of the traditional insulation materials have environmental drawbacks. Fiberglass installation requires protective masks and clothing and may contain cancer-causing formaldehyde, blown-in cellulose creates dust, some traditional insulation materials can grow mold when wet, and many foams can release toxic chemicals if they burn.
As effective replacements, the insulation industry has come up with some pretty sustainable and recyclable (or recycled) materials:
1. Cotton Batts
Also called blue jeans, are made from recycled, shredded denim and other plant-based fibers. They insulate well, have no formaldehyde and of course they don’t require new manufacturing, so they’re a sustainable product.
2. Sheep's Wool
Which has terrific insulating properties—but isn’t cheap. This product comes in rolls and costs 2-3 times as much as fiberglass.
A spray-on foam made of castor oil. Icynene insulates so well that homes need a fresh air ventilation system--and it can reduce energy costs by half.
With the information in this article, you’re now primed to insulate—good luck, and stay warm!