Re: Heating systems | <– Date –> <– Thread –> |
From: Daryl Anderson (danderigc.apc.org) | |
Date: Thu, 13 Oct 94 20:16 CDT |
Stephen, I cannot speak from experience with installed heat-pump system(s) but we at the EcoVillage at ithaca are currently evaluating them (specifically "ground-source heat pumps") as an alternative to our "baseline" design of high-efficiency gas supplementing passive-solar and energy-tight homes. We anticipate some efficiencies due to our neighborhood design which will build the initial 30 houses in 4 clusters of 8 and 6 houses with "energy centers" serving each cluster. This allows us to remove combustion (e.g. gas) units from the houses but also allows the heat-pumps to be sized to serve, e.g., 6 or 8 homes. Since our anticipated heating load for each house is a tiny fraction of a "typical" home this allows us to at least size for a normal heat-pump. It also allows a good deal of upfront savings in the system since we will not be putting in 30 systems, merely 5 (one for the common house)... IF we decide to go with them, that is. Current decision issues revolve around both upfront cost and operating cost as well as environmental impact (vs. gas) and heating modes. To summarize the issues : (1) upfront cost is indeed higher, some utilities will fold it in to downstream billings or otherwise flatten it out for you - we hope that the broad visibility of the ongoing EcoVillage project might pry some concessions from either the local utility or a specific manufacturer... (2) a very rough analysis by a member of our Energy Committee suggests that the heating-only GSHP technology may also be more expensive on an annual basis. Assuming a range between 300 and 400% efficiency (what they call their "COP" or "Coefficient of Performance") we still find that the electrical cost of operating the systems run from 10-50% over the basic gas system. This assumes our quite high electric here in Ithaca of $0.11 per kwh and natural gas is considered artificially-llow in price by many. Nevertheless we wonder. The primary cost advantages of the GSHP is if you allow it to bring in it's substantial efficiencies in delivering air-conditioning... this is something that we have never done in any of our programming for EcoVillage. AC (at least in the snowy hinterlands) seems a marginal need and an eco-downer. You might consider otherwise tho. (3) Environmental impact is interesting. Our rough analysis suggests that we may "generate" about 1/2 ton LESS CO2 per household per year if we go the GSHP instead of high-eff natural gas (HENG ?!). Many assumptions are rold in there including New York's specific mix of electric generation capacity (and not ignoring that our 20% nuke base allows a pretense of "clean" from less CO2). We will certainly be discussing this cost-pollution tradeoff as we consider options. (Baseline heating per house is only expected to run $150-200 per year so the overage for GSHP might be acceptable). (4) Other issues are (a) most of the older GSHP technology seems to use forced-air to distribute heat. Our group nixed that in programming and hopes to find a way to work our "hydronic" system (e.g hot water) in a radiant floor heating design. (b) For the time being the homes will need traditional hot-water (although we are designing for transfer to solar or solar-assisted we need to get conservative banks to approve, ahem... buy, our homes). We would really like to find a heat-pump mfg that can include full DHW (domestic hot water) in the package. Many can support DHW but I am told that only a newer technology called "de-super-heater" or something like that (!) can manage the higher temps and consistent supply that full DHW requires. If we can thence unhook entirely from the gas line we can also save a possible $32,000 "hookup" charge. I believe one of the COHO projects in Mass (Pine St or Pioneer Valley) is using heat pumps and you might also chase down an intentional community called Raven Rocks in Ohio that sex they are putting one in. Good luck. Keep in touch with any other info you get. -Daryl Anderson, EcoVillage at Ithaca ps. We hope to be moving in by late '95 with 20 households currently committed and designs for 30 houses.
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Heating systems Stephen Hawthorne, October 12 1994
- Re: Heating systems David Hungerford, October 12 1994
- Re: Heating systems Nancy E Wight, October 13 1994
- Re: Heating systems Daryl Anderson, October 13 1994
- Re: Re: Heating systems Roger Diggle, October 13 1994
- Re: Heating systems David Hungerford, October 14 1994
- Re: Heating systems David Hungerford, October 14 1994
- Re: Re: Heating systems Roger Diggle, October 14 1994
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