|Energy Prices Are Down|
|Energy Prices Are DownIn your editorial "Hey Newt, Here are Some Orphans with Potential," (HE May/June '95, p. 2) you state that "energy prices are considerably higher, so the value of the savings [for solar water heating] is actually higher than in 1980." Not so.
Energy prices peaked in the early 1980s and have been going down for years--in constant dollars, of course (see the U.S. Department of Energy's Monthly Energy Review, March 1995, Table 1.7). Motor gasoline prices peaked in 1981 and have dropped by 47 percent (through 1994). The cost of residential heating oil also peaked in 1981 and has dropped by 55 percent. Residential natural gas prices peaked in 1983 and have dropped by 29 percent. Residential electricity rates peaked in 1985 and have dropped by 22 percent.
The value of savings is lower now.
Alternative Energy Corporation
Research Triangle Park, NC
A/C Sizing Resource
I thought your May/June issue was great, especially the article on air conditioner sizing. (See "Bigger Is Not Better--Sizing Air Conditioners Properly," HE May/June '95, p. 19.) However, I didn't see any information about Air Conditioning Contractors of America (ACCA) in the article. They sell copies of Manuals J, D, and S, as well as provide information on software that implements Manual J (refered to in the article). Interested readers can reach ACCA at: ACCA, 1513 16th St., NW, Washington, DC 20036. Tel: (202) 483-9370. Fax: (202) 234-4721.
Lawrence Berkeley Laboratory
More on Ventilating Attics
Reading and understanding the two articles (especially "") preceding "" in the Mar/April '95 issue would help one understand why power venting attics is generally a bad idea. Even when it does make sense it should only be done after a careful analysis of the effect of the system on combustion safety, building energy use and moisture movement.
Before even considering power venting attics, one should measure duct leakage to the attic with a duct tester or a blower door and pressure pan.
With a blower door one could measure zone pressures with the envelope at -50 Pascals with respect to outside. This could lead to the discovery of some important air leaks between the attic and conditioned space. Even without a blower door, measuring attic, house, and outside pressures with and without the air handler and other exhaust fans on and off can expose duct leaks that are worth fixing.
If you can't reduce heat loss to the attic enough and decide it must be ventilated, you should at least measure the effect of this new exhaust fan, air handler fan, and any other exhaust appliances on the pressure in the conditioned space and attic with respect to each other and outside. In fact, if there are natural draft combustion appliances involved, you must do a combustion safety check that would include these measurements.
From what I understand of the building in "Venting Attics," I would estimate this diagnostic procedure could be done in three or four person-hours and would likely lead to significant energy savings and increased comfort. It would certainly provide some assurance that the attic fan hasn't created a combustion safety problem.