Insulation

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By Energy Circle Staff - August 18th, 2009

START HERE to learn about Insulation. Because the only thing worse than air leakage is heat transmission. Insulation conserves energy, increases comfort, and saves money, by keeping your hard earned heat inside. Find out how.

I: Overview
Insulation is one of your home's first defenses against wasteful energy spending. According to the Department of Energy, 50%-70% of the energy used in the average American home goes toward heating and cooling. That means you've got big (huge!) potential for savings by increasing your home's capacity to keep out either the summer heat or the winter cold, by improving your home's building envelope. The envelope is basically the sum total of everything that shields your home from the elements: paint, siding, framing, insulation, windows, doors, shingles, bricks, etc. Although none of these components can be viewed in total isolation, (an Energy Star certified window won't do you much good if you have string-beads hanging in your front doorway), insulation is an important part of the envelope. Inadequate (or absent) wall, ceiling and floor insulation can lead to massive energy waste.

II. The Basics: What you want to know about insulation. When we talk apples, we talk crisp and firm. When we talk insulation, we talk R-Value. So what IS R-Value? R-Value is the measure of an object's thermal resistance (how well it prevents heat from moving through it). Insulation is rated according to R-Value this way: the greater the thermal resistance, the higher the R-value, the better the insulation. To give you an idea: standard fiberglass insulation has an R-value of 3.14 per inch. A wall in Montana should have an R-value of about 18. So that's about six inches of fiberglass insulation. For comparison, an attic in Alaska should be about R60, and a floor in the Virgin Islands should be about R13. Most attics should be above R38. What constitutes an adequate, cost-effective R-value for your house depends on the part of the country and the climate you're in.

 
III: Taking it on: Bulk up your building envelope.

1. Evaluate your needs. We strongly recommend a home energy audit conducted by a certified professional. A quick look with an infrared camera during an energy audit will reveal the areas where heat is escaping your house, which signifies either an air sealing problem or inadequate insulation.

2. Make sure you are wearing a hat. This you can do on your own. Hot air rises. That means the attic is one of the most important parts of your home in terms of controlling heat loss. A simple way to make sure you are covered: pop your head up into the attic. If you can see floor joists, you need more insulation. If all you see is insulation, check how many inches deep it is. If your attic has a floor, pop up a board and do the same. Multiply that number by 3, and you'll have a very loose approximation of the R-value. An adequate R-value will differ depending on where you live, but should be somewhere between 30 and 60 . If your figure comes up short, you might consider adding insulation. Remember, too, that the insulation should be level and evenly distributed, without any gaps or holes; humps, bumps and low spots can compromise the whole system. And even if you have two feet of of high-quality fiberglass, a couple gaps for air leakage could reduce your R-value a lot, in addition to carrying unwanted moisture up into the attic. So make sure the attic floor is very well sealed before adding any insulation.
 
3. Determine what kind of insulation you need. Consult our insulation options to determine which insulation will work best for your house.

Ultimately, your home cannot be energy efficient if your building envelope is continuously leaking energy, and targeted insulation in problem areas can be a good way to prevent that. Whether you choose to hire an energy auditor right off and wind up completely retrofitting your home, or just supplementing the insulation in your attic with a few extra inches of cellulose, you'll be sure to enjoy a more comfortable indoor climate and a more manageable energy bill at the end of every month.

 

4. Assess the quality of your insulation. A number of things can compromise what would otherwise appear to be adequate R value. Fibreglass batts that are compressed by electrical wires or plumbing, and air leaks that allow flow within the insulation cavity can reduce R values by as much as 50%. Recessed lights in cathedral ceilings may compress insulation, and moisture from leaks or condensation can render r values weak.



Comments

I am a certified HERS energy rater and I appreciate your forum and the information you are providing. However, I noticed one common error above that should be pointed out. HOT AIR rises, due to its lower density at higher temperatures. HEAT, on the other hand, moves from more (hotter) to less (colder), regardless of orientation. Posted by craigsenglin on Jan 10, 2010 6:13pm
An outstanding share! I have just forwarded this onto a co-worker who has been doing a little homework on this. And he in fact ordered me breakfast simply because I stumbled upon it for him... lol. So let me reword this.... Thanks for the meal!! But yeah, thanks for spending the time to talk about this topic here on your web page. Posted by Ceiling light fixtures on Aug 29, 2012 9:53am

@craigsenglin -- right you are! Hot air rises because it is less dense than cold, and thus is only relevant in a case of convection -- air movement. Heat, being a higher energy state than the lack thereof (which us humans know as "cold") always goes away, this point being made in the laws of thermodynamics, in particular the one known as entropy.

In practical terms, don't just insulate your attic! Heat gets out any way it can. Insulate your walls, floors and basement.

Tom

Posted by Tom Harrison on Jan 10, 2010 6:43pm

@craigsenglin -- Many thanks for the comment. You're very right (that was an oversight of mine), I have updated the article to be more accurate and would love to hear any more insights you might have -- keep em comin!

Posted by Will on Jan 12, 2010 5:40am

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