R-values Aren't Always Useful

Steve Maxwell
July/August 2005
Add to My MSN


Content Tools

Related Content

Building SIPsmart: Raising the Dome

Michael Morley has an exciting update on the house he's building in Lawrence, Kan. The dome is start...

What's the Best Type of 'Green' Insulation?

Mother Earth News' green homes editor discusses eco-friendly insulation options, and explains why so...

3 Methods for Heating Greenhouses for Free

Smooth out the temperature range in your greenhouse by adopting one of these strategies for heating ...

How Do You String Wiring Through SIPS Panels?

When you build with structural insulated panels (SIPs), wiring isn't as much of a challenge as you m...

R-values are a measure of a material's resistance to heat; the higher the value, the better the insulative properties. Although they are a convenient and common yardstick to measure thermal performance, the usefulness of them is limited.

In a 2000 study by Brock University in Ontario, two almost identical homes ? one built with a stick frame and the other with Structural Insulated Panels (SIPs) ? were compared for energy efficiency. Thermal analysis revealed the 2-by-6 stick frame house (rated at R-20) performed at an R-4 equivalent, while the 4 1/2-inch-wide SIP home performed at a true R-17 level in 13-degree temperatures.

The reason for the wide discrepancy is because, unlike frame systems, SIPs offer continuous insulation values across large areas of airtight walls, unbroken by studs that would otherwise conduct heat and let cold air into the building. In terms of real-world energy conservation, the SIPs home consumed only a quarter as much energy over one year as its stick-built counterpart, even though R-value ratings were comparable.







Post a comment below.

 








Subscribe Today - Pay Now & Save 66% Off the Cover Price

First Name: *
Last Name: *
Address: *
City: *
State/Province: *
Zip/Postal Code:*
Country:
Email:*
(* indicates a required item)
Canadian subs: 1 year, (includes postage & GST). Foreign subs: 1 year, . U.S. funds.
Canadian Subscribers - Click Here
Non US and Canadian Subscribers - Click Here

Lighten the Strain on the Earth and Your Budget

MOTHER EARTH NEWS is the guide to living — as one reader stated — “with little money and abundant happiness.” Every issue is an invaluable guide to leading a more sustainable life, covering ideas from fighting rising energy costs and protecting the environment to avoiding unnecessary spending on processed food. You’ll find tips for slashing heating bills; growing fresh, natural produce at home; and more. MOTHER EARTH NEWS helps you cut costs without sacrificing modern luxuries.

At MOTHER EARTH NEWS, we are dedicated to conserving our planet’s natural resources while helping you conserve your financial resources. That’s why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.00 (USA only).

You may also use the Bill Me option and pay $17.00 for 6 issues.