 |
 |
 |
 |
|
 |
| A small void in the insulation dramatically reduces its performance. |
|
The cost of insulation is a two-sided issue. First cost is always critical to the budget; operating cost of the house interests homeowners. Striking a balance is the key.
On a first cost basis R.S. Means data spells out the economic effects of the various product choices.
Understanding Values
The nominal or clear-wall R-value of insulation is printed on the side of a batt or a bag. It is the thermal resistance of insulation installed perfectly without taking into account the conductance of the studs or other members in contact with the outside wall. On the operating cost side, actual or effective R-value of the wall and roof assembly is the key consideration.
In a study conducted by the Oak Ridge National Laboratory, Jeffrey Christian and Jan Kosny identified the effective R-values for different wall assemblies.
Effective R-values are impacted
by several factors:
If the effective R-value is significantly lower than the nominal R-value, the first cost argument needs to be reconsidered. Are you getting what you paid for and most importantly, are buyers getting what they expect?
McStain Enterprises, a production builder in Boulder, Colo., builds 300 houses per year. Historically, McStain used fiberglass batts exclusively. Over the last few years it switched to spray cellulose insulation in all its homes because customers see the difference in their utility bills says Kristen Shewfelt, McStain’s director of environmental programs. "Though the cellulose is about 25% more expensive, we believe it packs better and seals voids in hard to reach spots like band joists and penetrations. It also provides more comfort for our homebuyers."
Part of the decision was based on blower door tests conducted at McStain’s Greenlee Park subdivision in Lafayette, Colo. Three models were tested with three different insulting materials—all fiberglass, spray cellulose walls with blown fiberglass in the ceiling, and all cellulose. The blower door tests revealed striking differences. The fiberglass house resulted in just below .6 Natural Air Changes per Hour (NACH). The combination house was .4 NACH and the cellulose house was just over .1 NACH.
How do you take the next step in improving insulation performance? Learn from those that are doing the research. One is IBACOS, the primary consortium in the U.S. Department of Energy’s Building America Program. IBACOS is a leading public-private initiative focused on bringing systems approaches to the home-building industry Its Home Innovation Network is a collaboration of manufacturers and builders dedicated to the research, development and delivery of better homes and communities. It was established to be the vehicle to realize the IBACOS vision of homes offering unparalleled value and livability.
Knowing insultation costs—first and operating—and managing its installation are investments that make dollars and sense for you and your buyers.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Also See:
RS Means Data Comparison - CostWorks Insulation Projects
Install: Waterproofing Windows
Tool Test: Sliding Compound Miter Saws
© 2009, Reed Business Information, a division of Reed Elsevier Inc. All Rights Reserved.
Privacy Policy | PB Ad Info | PR Ad Info | CB Ad Info | GIANTS Ad Info | HZ Ad Info | Contact Us | Subscriptions
Copyright © 2009 Reed Business Information, A Division of Reed Elsevier, Inc.
