Article 1010393 of alt.home.repair: Path: news.misty.com!not-for-mail From: nicksanspam@ece.villanova.edu Newsgroups: alt.home.repair Subject: Re: Energy savings of a ' fridge Date: 11 Apr 2008 08:20:46 -0400 Organization: Villanova University Lines: 34 Message-ID: References: <47fc1e7a$0$19857$470ef3ce@news.pa.net> NNTP-Posting-Host: acadia.ece.villanova.edu X-Trace: max.inside.misty.com 1207912856 31889 153.104.44.130 (11 Apr 2008 11:20:56 GMT) X-Complaints-To: abuse@misty.com NNTP-Posting-Date: Fri, 11 Apr 2008 11:20:56 +0000 (UTC) Xref: news.misty.com alt.home.repair:1010393 Richard J Kinch wrote: >>... How much energy would we save if we kept ice trays in a baggie? > >A significant amount compared to the bogus Energy Star efficiency ratings, >butat about $1/day total to run a real refrigerator in a real household >environment, I don't know that it is enough to justify the nuisance. I do >know it is enough to demonstrate the absurdity of Energy Star. My ice cube trays hold 0.796 pounds of water. Freezing one from 60 F takes (60-32+144)0.796 = 137 Btu, ie 0.04 kWh of heat. A fridge with a COP of 3 could move that with 0.013 kWh worth 1.3 cents at 10 cents/kWh. Know anyone who freezes 1/0.013 = 75 ice cube trays per day? :-) The trays have about 4"x10" of ice surface. Over a month, they might lose 1/4" of depth in my frost-free freezer. How much does that cost? >Polyethylene bags, by the way, are not very effective vapor barriers... Foil helps, aluminum helps, but http://www.devicelink.com/mpb/archive/98/09/005.html says 100 in^2 of "low-density polyethylene" loses about 0.4 grams of water per day per mil (0.001") of thickness at 40 C (104 F), with 0% RH on one side and 35% on the other. A graph shows how this decreases linearly with inverse (1000/T(K)) temperature. How much would that cost? EERE/DOE say a 6 mil poly film vapor barrier has 0.06 perms, ie 1 ft^2 transmits 0.06 grains of water vapor per hour (out of 7000 grains per pound) with a 1" Hg differential pressure at 73.4 F. How much would that cost? Nick