“Reduce your carbon footprint!” “Build sustainably!” “Go solar!” “Go green!” What does it all mean, and where is the line between doing what we can for the environment and taking care of our home finances? Most of us embrace these principles, but the reality is that only a small percentage of us are actually acting upon them. Times are tight and most folks these days are more concerned with their financial security than with saving the planet. The good news is that when we do reduce the utility costs in our homes, we also help to reduce our carbon footprint, thereby doing our part to help the environment. Furthermore, as we make these types of investments, our return increases as energy costs go up.
I am in the business of “green” home building and remodeling. I also work with a local startup company analyzing home energy efficiency and installing both residential and commercial solar hot water and photovoltaic systems. I thought I’d share some feedback from the field in a series of articles. I’ll discuss which methods of home efficiency improvements have been the most cost-effective, how to prioritize them, and how to do many of them yourself.
Here in New England, our biggest utility bill is usually for home heating. That’s where the primary focus should be. You might be really excited about getting solar panels up on your roof, but if your home is built like a barn, you should bring down that heating bill first. When analyzing the energy efficiency of a home, there is an accepted order in which to proceed. First we look for air leaks, followed by a review of insulation. Then there is a heating system analysis with a look at any door or window improvements. The fun stuff, the solar stuff, is really the icing on the cake. Solar thermal or SHW (solar hot water) and PV (photovoltaic, solar electricity) are the last on the list.
Consider your home’s envelope, the structure that defines the heated portion of your home. The tighter your envelope, the lower your utility costs. So, perhaps you have six inches of fiberglass insulation in your walls, some additional insulation in your attic, and you recently upgraded your windows and did a bit of weather stripping here and there. Sounds good enough, but how do you know?
Introducing the Home Energy Audit
Enter the blower door test. It utilizes a high-speed fan that depressurizes your home. This device is set up in the opening of an exterior doorway with all utility vents closed off. The fan, attempting to set up a vacuum effect, steals fresh air from any available source. Any and all cracks in the envelope are employed. It’s fun to walk around a house with the homeowners while this test is being conducted. They are always surprised to find weaknesses in their home’s envelope that they never suspected. Air pours from recessed ceiling lights, under baseboard wall trim, all around doors and windows, through electrical wall plates, around chimney-to-roof tie-ins, on the inside of kitchen cabinets and in the cellars. The charming old Capes with the laid-up stone foundations and inaccessible crawlspaces are among the worst. We often tell folks to leave the cobwebs in place before we arrive. These tiny engineering feats are great tell-tales for air drafts while the fan is running during the test.
Exposing the drafts is one phase, but the real kicker is in the analysis of the digital readouts. You might think that a little crack here and there is not a big deal, and you may be concerned about having your home too tight anyway. When the numbers are crunched and it reveals the equivalent of a one- to three-square-foot hole in the side of a house, this is a bit of a jolt. So this gets back to our prioritized list of improvements. A new home with 2×4 walls that utilizes state-of-the-art air sealing and insulation can outperform a traditionally insulated 2×6-walled house. The data reinforces the priority of air sealing being first on the list of home energy improvements.
A blower door test (commonly known as an Energy Audit) typically runs from $200 to $450, depending on the size of the home’s envelope. Many people find that this test pays for itself within the first heating season. It provides focus for your energy improvements and keeps you from spending your hard-earned dollars in the wrong areas. Recently, a homeowner in Vermont had gotten his three estimates for replacing the 15-year-old insulated windows in his home. Before making any installation commitments, he decided to proceed with a blower door test. The results revealed that the window seals were in fine shape! He was able to forego the $15,000 for new windows and instead spend about $3,500 for air sealing and beefing up the attic insulation.
Incidentally, if your home is electrically heated and you meet certain income requirements, you can receive a free Energy Audit and a package of energy improvements at very little cost through PSNH.
So here we are with the test results that list the breaches in the home’s envelope. In the next post we will review strategies and tips for sealing these cracks, many of which you can do yourself. We will also talk about the home that is “too tight” and the science of properly handling this important issue.
(originally published in Common Threads, a community newsletter for Harrisville, NH)