<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Sacie, I just looked at the Drake Landing site<div>It is -20C and has been below -15 or so for a while</div><div>Looks like the 52 houses are drawing 310 or so kW. This is about 6 kW per house or 20.5 kBtu/hr for a -4F temperature and 1500-1800 sf above-grade house square footage. That is not bad, but it could likely be dialed down by 25-50% with a reasonable upgrade in insulation windows, airtightness.</div><div>They have two tanks, each with almost 30 000 gallons. So that works out to 60000/52= 1150 gallons per home. If you check the annual report, 80% of the solar energy put into the ground is lost, but over 95% of the energy put into the tank is able to be used. So maybe 2000 gallons might be enough for one home, and should be enough for a super insulated one.</div><div>Note that they have 8 solar panels of about 4'x8' each to collect the heat (that aint cheap either).</div><div><br></div><div>Your questions got me thinking.<br><div><div>On 2011-01-12, at 12:09 PM, Sacie Lambertson wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">Thanks John, possible to use a central tank and find such savings in a single house? How large a tank are we talking about? S<br><br><div class="gmail_quote"><i>On Wed, Jan 12, 2011 at 11:03 AM, John Straube <span dir="ltr"><<a href="mailto:jfstraube@gmail.com">jfstraube@gmail.com</a>></span> wrote:<br>
</i><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div style="word-wrap: break-word;"><i>I have friends who worked on this. The houses are all R2000. It would have been more economical to insulate better.. and just using the central tank, no ground loop, would generate most of the savings with far less cost.</i><div>
<i>The overall system is very expensive.</i></div><div><i>Check under publications for the newsletters</i></div><br></div></blockquote></div><div style="visibility: hidden; left: -5000px;" id="avg_ls_inline_popup"></div><style type="text/css">#avg_ls_inline_popup{position: absolute;z-index: 9999;padding: 0px 0px;margin-left: 0px;margin-top: 0px;overflow: hidden;word-wrap: break-word;color: black;font-size: 10px;text-align: left;line-height: 130%;}</style>
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<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div>John Straube</div><div><a href="http://www.BuildingScience.com">www.BuildingScience.com</a></div><div><br></div></span><br class="Apple-interchange-newline">
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