In the article "What Stays One When You Go Out" (HE Jul/Aug '93) the sidebar "The `Set and Forget' List" reports that a FAX machine will consume 2-8 kWh/month. I suggest that you actually monitor one. My Panasonic KX-F90 says on the back that it is a 65 watt machine. When I tested it for 24 hours in the TAD/FAX mode (which is the answering machine mode that automatically switches to FAX if it receives a fax signal during the answer mode) my monitor indicated almost 2 kW.

My clue was the fact that our electronic consumption had gone up and the size of the cord. I know that's not much of a criteria but when you're looking for clues, you go with what catches the eye. If you calculate the 65 W times 24 hours you get 1.56 kWh and I guess my old and relatively cheap monitor isn't all that accurate. Anyway, I would be interested in another look at the energy consumption of fax machines.

I did try switching to other modes (FAX and TEL) and it seemed that the energy use didn't change. It would be nice to confirm or refute my finding so that those of us who care can buy fax machines that aren't energy hogs.

Henry Hammer
Los Osos, CA

An Expensive Project?

I was just reading the Home Energy article titled "Weatherizing (Almost) an Entire Town" (Jul/Aug '93) and was disturbed. This article described the Espanola retrofit project at Ontario Hydro. It stated that the cost of the project was $10.6 million Canadian ($8.5 million US) including customer costs, and the savings are 2,000 kW.

These numbers imply a cost of $4,240 US/kW saved, which is three to five times greater than the cost of typical new power plants ($800 to 1600 $/kW). There may, of course, be other reasons to undertake small but ambitious pilot projects. The knowledge gained from such projects can help utilities do better in the future, both in terms of technology choice and program design. However, no one should lose sight of the fact that conservation is supposed to save society money.

Jonathan G. Koomey
Staff Scientist
Lawrence Berkeley Laboratory

More Insulation Damage

The moisture damage noted by Mr. Ask in floor truss construction (see "Insulation Damage," HE Jul/Aug '93) can most easily be avoided by applying spray foam insulation directly to the wager board and between truss ends. As noted by Mr. Ask, the problem is primarily due to airborne moisture migrating through the fiberglass and coming in contact with half in. thick wafer board which is exposed to exterior temperatures.

Spray foam insulation (ozone-safe, water-blown, 1/2 lb. foam) applied directly to the truss will not have this problem because it will fit the contours of the truss perfectly, adhere to it and prevent airborne moisture coming in contact with the wafer board. Foam is 30 to 40 times less air permeable than a fiberglass batt. The almost impossible challenge of tightly sealing around floor joists is avoided with the use of foam because the vapor barrier is only required to retard vapor diffusion, not to prevent air infiltration.

Graeme Kirkland
Icynen Inc.
Mississagua, Ontario

The article "Weatherization Assistance: The Single Family Study," (HE Sept/Oct) should have reported that during 1989, 198,000 single-family or small multifamily homes were weatherized by the Weatherization Assistance Program (WAP), resulting in a total (estimated) savings of nearly 3.5 trillion Btu during the first year after weatherization. Assuming there are 5.8 million Btu per barrel of oil, the program saved the equivalent of 601,000 barrels of oil during 1990-1992. The table listing nonenergy impacts of WAP should have appeared as follows:

                                              Value of the
Type of nonenergy impact                   impact per dwelling
______________________________________________________________
Increased property value                          $126
Reduced incidence of fire                           $3
Reduced arrearages                                 $32
Federal taxes generated from 
   direct employment                               $55
Income generated from 
   indirect employment                            $506
Avoided costs of unemployed benefits               $82
Environmental externalities                       $172
______________________________________________________________
TOTAL                                             $976