This article was originally published in the November/December 1993 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.



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Home Energy Magazine Online November/December 1993




Fax Machine Energy Use

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


Editor's Note: Reader Hammer's experience shows that fax machines vary widely in energy use (though we suspect his must be incorrectly labeled). At least 3 different fax technologies exist--thermal, laser and ink-jet--with ink jets offering the lowest energy use. We gave an average value, but as Hammer found: few homes are typical. This example just reinforces the article's conclusion that many items consume significant amounts of electricity without any obvious signs or consumer control. By the way, there's no standardized test procedure for fax energy use, though ASTM is developing one. Also, the Electric Power Research Institute (EPRI) and the American Council for an Energy-Efficient Economy (ACEEE) will soon publish a guide to energy-efficient office equipment with a section devoted to faxes.

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


Editor's Note: Reader Koomey identified a shortcoming of the Espanola project. However, the project's goal was not only to implement cost-effective conservation measures, but to discern which measures were cost-effective, and which were not. Ontario Hydro took some chances. The researchers wanted to determine which conservation measures could be broadly implemented. To answer these questions, they carefully collected both cost and energy data. Simply combining the costs and energy savings suggest that the conservation measures were not cost-effective, even though that was only one aspect of the project. W.R. Ruhnke, a senior advisor in Ontario Hydro's marketing and decision support department, notes that total project costs to date are (Canadian) $10.1 million, with $6.6 million going toward the program but $3.5 million for research and evaluation. He adds that the estimated cost/kW for the project was (Canadian) $2,600 and predicted annual energy savings were 8.4 million kWh, which presented 17% of the town's annual electric use.

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 In the article What Stays On When You Go Out (HE Jul/Aug '93), a sentence under the subheading, Refrigerators should say the thermostat should be set to the lowest possible temperature to achieve better efficiency.


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