Re: Heating systems
From: David Hungerford (dghungerforducdavis.edu)
Date: Fri, 14 Oct 94 13:39 CDT
On Thu, 13 Oct 1994, Daryl Anderson wrote:
>     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.

How would you control the temp in the individual houses?  Would you 
simply run one loop to each house (therefore having one heat exchanger 
per house) or would you have one system for the whole cluster
My research on people's perceptions of comfort 
indicates that control, or rather the *ability* to control one's thermal 
environment has more to do with how comfortable people feel than the 
actual temperature (within limits, of course).  This means that if 
individuals don't have control over the temperature of their units, then 
they will be more "uncomfortable" and probably more cranky at general 
meetings.


>    (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. 

Whoa!  You're not counting the cost of gas, and you're somehow assuming 
that the electric resistance backup must kick in.  The COP numbers assume 
something very important, that is, that the units operate to maintain a 
*constant* temperature all year 'round, they also assume an "average" 
house, that is, a stick-built, low mass, faced any-which-way, 
sort-of-insulated house typical of U.S. building practices since WWII.  
If you build houses that minimize heat gain and loss (easily accomplished 
with off-the-shelf materials) your heating/cooling system doesn't have to 
operate nearly as much as the "average" tests assume.  Further, if you're 
willing to allow the temperature inside your house vary even as much as 
5-8 degrees F on either side of the "average" thermostat set-point (about 
72-73 F) you can save an enormous amount of energy.  That is, if you're 
willing to put shorts on in the summer, and a sweater in the winter, your 
"backup" systems (the real energy hogs) never have to kick in.  Hey 
folks, the thermal nirvana assumed by HVAC engineers is an historically 
emergent phenomenon (and a bit of an addiction) peculiar to Industrial 
countries and the U.S. in particular. The assumption that a house should 
be able to maintain a constant temperature is a product of the existence 
of a technology capable of accomplishing that goal, that is, compressor 
a/c and forced air heating, all of which became widespread during a 
period of essentially free energy.  If you apply the "test" of 
maintaining a constant thermal environment to alternative technologies, 
they are going to lose out.  If you are willing to buy into the idea that 
people's comfort needs are in large part socially constructed, that is, 
that they are to some degree the product of the dominant technology--just 
as social alienation is to some degree the product of the dominant 
housing form--then our comfort "needs" can change.  In other words, 
people need a constant thermal environment for the same reason they need 
a double-car garage, a disposal, and a fenced back yard with private 
patio--not because there is some "underlying, stable preference" for them 
but because we live in a social world that *expects* that this is what we 
want.

Oh well, you guys just got the short version of my dissertation.  

David Hungerford
Muir Commons

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