Poor Insulation Work Adds to Home Retrofit Challenges
As a remodeling contractor, I read your recent article “The Challenge of Existing Homes” [see
Most homeowners who have their homes insulated have no idea if the job was good or not. For that matter, most insulation crews have no idea if they did a good job. For the past few years I have been doing quality-control audits on utility-rebated insulation work done on older homes in Newton, Massachusetts. Almost invariably the insulation work consists of blowing cellulose into the exterior walls at too-low pressure and with no attention to air-sealing. The net result is insulation coverage often as low as 60% of the area of the exterior walls and leakage rates well above 5,000 cubic feet per minute at 50 pascals (the result is extrapolated, because often we can’t reach a 50-pascal pressure difference—even after the insulation work has been done). These homeowners have no idea they could get much, much better. Sadder still, the insulation crews have no idea they could do much, much better. And we’re stuck with these bad insulation jobs for decades.
How can we create a steady demand for quality weatherization work? I think the first step is to establish a metric that can be readily understood by the general public. Your case studies point to part of the problem: the energy load of one house is measured in million Btus annual total consumption, another is measured in Btus per hour of peak load, and the third is measured in million Btus annual consumption, but split between heating and cooling.
When I give insulation workshops, I ask participants how large their houses are and how much they pay for electricity, gas, and oil. Nine out of ten have only a vague idea. So much for calculating and comparing Btus per square foot per year with such a group. The measurement system needs to be much simpler and more intuitive than the numbers you used in the case studies.
We should encourage more widespread use of HERS [Home Energy Rating System] numbers. HERS ratings are far from perfect (in particular when applied to older homes), but they will only get better with more widespread application. If real estate agents were required to provide HERS numbers with property listings and if remodelers were required to reduce the HERS ratings of existing homes by a certain percentage to get a final inspection signoff, an essential feedback loop would be closed and a new level of demand for quality weatherization work would be created.
My remodeling company has started to calculate before-and-after HERS ratings for our projects. It has not been easy, but it will get easier. My crew and most of our clients have been receptive to the idea. I am confident it will soon be one of the most important numbers we calculate. Using HERS ratings backed up by actual performance data over time, both we and our clients will know when we get our energy improvements right and when we get them wrong—and as a result we will get them right much, much more often.
Published September 28, 2007