I recently had an energy audit done by a company who shall remain nameless (their service after the audit has been embarrassing). Despite their post-visit incompetence, I did learn a few things, and I started a project to evaluate where my energy goes. Here’s a quick summary* [graphic no longer available]:

First: Yes I am ashamed of our electricity usage. I have been trying to change the family behavior but it is a losing battle. I’ll not go into detail because I value the relationships with my wife and children. I suspect that in the fall, when two go off to college, our electricity usage will drop dramatically and we’ll see a bit of a drop in gas usage.

Second: Notice that our heating energy usage is three times our electricity energy usage (in BTUs) yet the cost is about the same. That’s right, I purchased more than three times the energy from the gas company but it cost me about the same as my electricity. In other words, electricity per unit energy is more than three times the cost of natural gas. (If there were an efficient way to generate electricity with gas, I would consider doing it.)

Knowing these numbers, I can now begin to evaluate options for energy reduction because I can determine the costs and benefits of many different actions and pick the most effective ones. For example, I now know that every kilowatt-hour I save is worth about 11% of a therm (11,000 BTUs). Or every 100,000 BTUs of gas (1 therm) I save is worth just over 87 kilowatt-hours.

What direction will I go?

Electricity: After switching all of our light bulbs to compact fluorescent and upgrading to Energy Star appliances, the next major leap on the electricity use reduction is behavior change or kicking out some of my family. Since I have two starting college in the fall, kicking out is easy (though expensive). As I’ve found over the years however, getting people to change behavior is not.

Gas Usage: Cooking is a relatively small portion of our gas usage. The bulk is heating. I’ve put in the auto-setback thermostats and added insulation to the attic. I’m just getting started on tightening up the house. I believe that the biggest bang for the buck will be reducing the passive loss of heat. Here are some steps I’m considering:
1. Remove fiberglass insulation in attic, spray foam on the ceiling, seal all electrical and other penetrations, replace the fiberglass. This will reduce air leakage to the attic.
2. Seal around all electrical boxes (outlets, switches)
3. Spray foam insulation at sill plate (transition between foundation and house)
4. Seal around all windows (remove moldings, and foam between window and framing.
5. Remove siding and put up rigid foam, tape joints, reattach siding
6. Put 2″ of rigid foam insulation on exposed concrete that abuts living spaces
7. Insulate walls between garage and house (garage is unheated).

Granted some of these projects are “small” (#2) and some are huge  (#5). I’ll be starting small. First and foremost, I’ll be addressing air leaks. (#1 and #2)

-Mark

*Electricity supplied by Hudson Light and Power. Gas supplied by NStar. I divided the total bill by the total usage. Therefore delivery charges etc. are averaged over each kilowatt-hour or therm.