Negawatts in the Attic

This fall I decided it was time to add some insulation to our attic. The insulation from 22 years ago, blown-in cellulose, was originally 8" deep and rated R-30. Here's the way things looked before I started:

 

Over time, the cellulose had settled a little, from time and from occasional trespass by birds and by me, and near the gable vents it had gone gray from blown-in dirt.

The EnergyStar program recommends attic insulation of R-38 to R-60 in most of Ohio. Even if added rolls of insulation compressed the existing cellulose somewhat, reducing it to, say, R-20, I figured that adding R-30 would still give me an effective rating of R-50, and would be worthwhile. The best way to 'green' a house starts not with consuming alternate sources of energy, but with conserving energy, avoiding energy production in the first place, a concept sometimes known as negative watts, or negawatts. I wanted to generate negawatts in my attic.

The access to the attic is only through a hatch located in a step-closet (the floor is not flat but goes up like huge steps). The hatch opening is about 21" by 23", so I had to work within that limit.

In addition, the attic, as seen above, is completely unfinished, without flooring. When I was up there I had to step carefully from joist to joist. So, after cleaning up the old TV antenna and other junk, then measuring, my next task was to install some boards (2' by 4') to make working there easier. I envisioned full 'aisles', but there were so many wires running atop the joists -- alarm system, electrical, phone -- that instead I had to create a chain of islands of one or two boards. I did not want to lay a board down on any wires.

After measuring, it was clear that the job would require two steps; each step would be to load the minivan with insulation, drive home, tote the rolls up to the attic, and install them. It took two days, one for each step. With a single light bulb in the attic, I constantly wore a camping headlight, and due to the dust, I wore a mask. Each mask had acquired a brown patina by the end of the day.

Here are the rolls for step one, awaiting installation.

The preformed trusses blocked almost every roll, so a large number of cuts into the insulation were needed to get them to lie flat and snug.

Notice the pink plastic wrap? This innovation kept the fiberglass dust down substantially, and reduced the likelihood of skin irritation from handling the stuff. (I wore gloves, of course). The plastic is perforated to allow moisture to pass through. I often slit the plastic to help the fiberglass expand to full size. 

Here's the attic (well, part of it) with the insulation installed. Orange tape marks where the boards lurk underneath.

Has the added insulation made a difference? It's too early to tell. One winter can be colder than another, plus, our heating system is a hybrid -- electric heat pump above 35°F, natural gas furnace below that temperature -- so a true comparison has to be based on both energy sources. Converting the kilowatt-hours of electricity and CCF of gas to BTUs and adding them together will eventually give me an idea of what's been accomplished. (1 KWh is 3412 BTUs, and 1 CCF of gas is 100,000 BTUs). After all that work, I sure hope it helps!