Archive for November, 2009

So You Think You Can Insulate?

House nearing completion

Arlington, MA Home Renovation - Subtle but important changes. The window details hint at the thick layer of rigid foam insulation just beneath the siding

The story starts the same in most cases – you want to insulate your home to save money on energy costs. Sure, you can do it yourself, as long as you put the proper thought into it beforehand. But proper insulation is only one part of the solution. If you really want to save on energy costs, the other, and perhaps bigger, issue is air sealing.

Proper sealing of the home and proper installation of the insulation help to make the home more comfortable year-round. I say “proper” because some people make the mistake that “more is better.” Actually, less might be better if it’s installed properly and applicable to the climate of your area.

This past spring, an Arlington MA home became a test case for the Massachusetts Department of Energy Resources (DOER) and our regional utility company NSTAR. Rather than adding complex heating and cooling systems to the home, the on-going project focuses on reducing the overall energy consumption of the building. Improving the building’s envelop involved upgrades to both the air sealing systems and the insulation of the home. But even within this project, one of the few mistakes they encountered was the installation of 6-in foam in the attic instead of 4-in foam, as originally planned. The lesson learned, so far, is that the extra time and expense of installing the additional 2-inches hasn’t been worth it. Read more about the project at‘s web site and read a diary of the project from the homeowner’s point of view at Massachusetts Super Insulation Project‘s blog.

But not everyone can become part of a test case involving a government-sponsored research project, right? So you might decide to undertake a simpler project, such as insulating your attic or your basement ceiling. There are many more options for insulation than there were even 10 years ago. So if your current insulation is more than 10 years old, you might consider removing the current insulation and replacing it with a more appropriate type, based on your home construction and location.

Where to start? I highly recommend your first stop be to visit the Home Energy Saver calculator, developed and available online at the Lawrence Berkeley National Lab web site. This is the most in-depth savings calculator I’ve ever seen, so begin your research there. According to the calculator, the average home in Arlington MA has an annual energy cost of $2008, whereas an energy-efficient home’s annual energy costs are $1175 – a savings of $833 per year!

Still thinking “more is better”? Well, too much insulation in a home, in addition to costing more, can cause moisture problems and may even end up causing poor air quality and health problems. Insulation is measured in terms of “R-values,” so be sure to install the proper r-valued insulation for your home’s design, climate, and the section of the house to be insulated (attic, basement, etc.). Consult the U.S. Department of Energy’s Recommended R-Value map for the proper ratings for the various types of insulation.

If you plan on replacing some old insulation, also consider having it professionally removed instead of doing it yourself. You never know what surprise you might encounter, from skeletons of dead rodents to fresh bat guano! You can read more about the importance of having the insulation professionally removed at the BatGuy’s web site.

If you’re interested in learning more about energy-efficient homes in the Arlington, MA or Cambridge, MA areas, my web site at Also see the list of additional resources below.

Until next time, Peace!


Additional Resources: