I’ve been performing a semi-deep energy retrofit to my home for the past 5 years, and at my current rate of progress, it will be another 5 years before I’m complete. This leads to a question; how does a person prioritize the work to be done? Are the easiest items to complete done first, or the stuff that provides the biggest return on investment a better place to start? This blog discusses my suggested priorities.
Part of an energy auditors’ job is energy analysis, which includes analyzing historical energy consumption data to determine if usage is as expected. One method is to compare a home’s energy use to some average (the local rural electricity provider I contract with calls this “compared to your neighbor’s”). This average could be the national average, but it’s better to compare at a more local level, such as by state. There are a few sources of this information, one that I have been using is: U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. This dashboard provides me with several different energy consumption metrics, expressed in MMBtu’s and kWh, broken down by state and also displays national averages for the US (sorry my Canadian friends).
I recently had the opportunity to attend a BS and Beer meeting in Kansas City, MO where the meeting took place in a home under construction. The home was being built by Aarow Building (Jake Bruton) of Columbia, MO (they recently opened an office in Kansas City). The home is a single level, slab on grade with around 3,250 square feet. At the time of the meeting, the home was just finishing the mechanical, electrical, and plumbing systems and about to move to the insulation phase. A perfect time for a mid-build blower door test.
The purpose of a mid-build blower door test is to confirm that the home is on track to meet the air tightness metric (Jake informed me that all his new homes are contractual bound to achieve 1 ACH50 or less) and to find any missed opportunities in the air sealing of the home. The mid-build testing can be simple, get the home to negative or positive 50 Pascals of pressure and record the CFM rate, this type of testing is called “single point”. If you feel the CFM rate (or the calculated air changes per hour at 50 Pascals number) is too high, set the fan on “cruise control” and go find the air leak locations. There’s no need to perform multi-point testing this early in the build, (a type of blower door testing where CFM rates are measured at progressively lower pressure points, usually starting at 60 Pascals), save that type of testing for the final blower door test. Continue reading “An Airtight Home, What Do the Blower Door Numbers Mean?”
Through the years, I’ve taken a lot of training and attended dozens of conferences about reducing energy consumption in existing homes. Everything from BPI’s Building Analyst certification to Huber’s Building Science Crossroads. Many of these training courses discuss the easiest and most cost-effective areas of concentration for energy reduction, the so-called low hanging fruit. In this shallow energy retrofit blog, we will be discussing the most common location to improve a home’s performance, the attic and/or roof.
Several years ago, I performed a roof replacement for a customer, the customer wanted to change their older and failing asphalt shingled roof to a steel roof. We stripped the old shingles and existing underlayment off, installed new synthetic underlayment and new steel over the 10/12 pitched roof. I felt confident that this new roof would last many years.
The following year, the same customer asked if we would replace several windows in the upper level of his story and a half home. The old windows were due for replacement, the single paned wood units appeared to be from the mid-1900’s. Woodpeckers had pecked a hole nearly completely through one of the windows. Several others were painted shut. Again, a straight-forward job we had done dozens of times before.
The home with the roofing and window replacement that resulted in “attic rain”.
The spring after the window replacement, I received a call from the customer saying his roof was leaking. He had water dripping in several areas in the upper level of the home. A visit to his house did indeed show water damage, though it was not the result of a bulk water leak from the roof, but instead, air leaks from the interior had formed frost on the attic side of the roof sheathing, the home had never had this issue before. I surmised that replacing the five upper-level windows had changed how this home handled air and moisture just enough to cause frost to form in the attic. My first building science lesson about the unintentional effects of a shallow energy retrofit. Continue reading “Energy Conservation-Shallow Energy Retrofit”
