Subject: A measure of solar house heating ease

From: [email-masked] (Nick Pine)
Date: 3 Jul 1996 13:28:24 -0400

How hard is it to make a 100% solar heated house in various parts of the US? 

Norman Saunders, PE, uses a simple measure:

       average sun that falls on a south wall
   E = --------------------------------------.
         70 F - average outdoor temperature

The higher the number, the easier the climate. Here are some values
for a few cities using some NREL average weather data:

                   Jan    S wall              Dec    S wall
                   temp   sun       E         temp   sun      E       

Abilene, TX        42.8   1400      51        45.5   1400     
Albuquerque, NM    34.2   1640      46        35.3   1610
Atlanta, GA        41.0   1120      37        44.5   1110
Austin, TX         48.8   1200      57        56.6   1200
Binghamton, NY     21.1   790       16        26.5   610      14
Bismark, ND         9.2   1070      18        14.0   1110
Boulder, CO        29.7   1370                31.0   1180     30
Buffalo, NY        23.6   680                 29.1   550      13
Carabou, ME         8.9   990       16        14.8   780
Chicago, IL        21.0   910       19        26.6   740      17
Concord, NH        18.6   1060      21        24.3   880      19
Detroit, MI        22.9   770       16        28.3   610      15
Flagstaff, AZ      28.7   1580      38        29.6   1560
Fresno, CA         45.7   880                 45.4   830      34
New York City, NY  31.5   980       25        36.6   860      26
Phila, PA          30.4   1000      25        35.8   900      26
Raleigh, NC        38.9   1130      36        42.6   1100
Richmond, VA       35.7   1090      32        40.1   1030
San Francisco      48.7   1050      49        49.4   1050
Seattle, WA        40.1   480                 40.5   420      14

It looks like Steve Baer has it easy in Albuquerque, as do people in Texas :-)
But Norman has designed 100% solar houses even in places like Binghamton...

Nick

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From: Michael Delceg <[email-masked]>
Date: Sat, 06 Jul 1996 15:11:10 +1300

How is average sun determined? Is it average daylight
hours for that latitude?
Mike

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From: Kathy Ging <[email-masked]>
Date: Sat, 6 Jul 1996 01:54:59 -0700

I am not an expert on this but having friends in the solar
trades, I recall that solar heating is partly a function of       
the degree days   for a locale. E.g., Eugene,
OR, may seem like it would not be a great place for solar
heating, but because of our winter cloud cover, creating a
relatively benign climate, we do not have 
so many sub-freezing days. That makes it easier for solar
water heaters to boost the temperature of the water and
for solar to provide a measure of space heating too.
The flat plate rather than the tracking collectors have, I think, 
performed better here because of our diffused radiation.

An interesting phenomenon is the fact that one solar monitoring
that was done in OR some time ago found that one of the best
performing DHW systems in the state was located in one of
the poorest solar radiation sites in the state - nr. the
coast. The engineer who monitored the system attributed
the superior performance to the attention to installation detail
of the installer - a man with plumbing background who was installing
a DHW on his own house!

OR DOE has continually reported that solar energy can 
provide 50% of Oregon*s domestic water and space heating
needs. The reason that 20 year plans a decade ago by the
OR Dept of Energy historically project only 5% solar DHW
and 2% space heating within 20  years is a function of the lack of 
leadership in political and govt squares, not of a lack
of solar insolation. The sun is available, the technology
is available, the motivation to put these together is not.

Energy at the Crossroads report by the GAO sometime ago said
that the major obstacle to the renewable energy transition
in the PNW was the regional utilities that might not want
this technology transfer to occur. If 80% instead of 20%
of the nation*s utilities were owned by publicly elected
boards like Rural Electric Cooperatives, PUDs and munis
(instead of by Investor Owned Utilites -IOUs - guaranteed
profit monopolies dominated by E Coast investors), we
might see some changes in the energy mix.  

When Hunter and Amory Lovins can energize their +/-5,000 sf
house/office for $10 a month and apologize for having 10
yr old technology that wastes energy, the rest of us can
hope to learn a few of their techniques to apply after
our natural gas binge is over. 

By then perhaps we will be teaching degree days in school
instead of it appearing as an arcane piece of info on NGs!

Kathy Ging, Secretary, NW Eco-Building Guild, Eugene chapter

> How is average sun determined? Is it average daylight
-