re: weather station - sunshine?
25 may 2004
alec chiasson wrote:
>...i am reminded of the tmy2 simulations that nick did awhile back
>(wherein i bemoaned the fact that there is little canadian equivalent
>to us insolation data).
i recall some sbse (society of building science educators) talk about
computer programs that generate tmy files from other weather data files.
i don't think they were cheap or easy to use. you might ask nrc about them.
another approach to solar house heating simulation is to find the long-
term worst-case month for solar house heating in the sense of the minimum
ratio of solar energy that falls on a south wall on an average day divided
by the indoor-outdoor temperature difference. the solarium workbook says
a south wall in halifax gets an average 2341 wh/m^2 on an average -3 c
jan day and 1650 (523 btu/ft^2) on an average -1 (30 f) dec day, and
2341/(20-(-3)) = 102 and 1650/(20-(-1)) = 79, so december looks like
the worst-case month.
then you might toss a die (or two coins) and reckon 1-2 is a cloudy day
(0 wh/m^2), 3-4 is an average day (1650 wh/m^2), and 5-6 is a clear day
(2x1650 wh/m^2) and record the amount of backup fuel the house would need
after a long series of coin flips. to save time, you might start by
calculating the amount of stored heat the house would have after a long
string of average days. an overglazed direct gain solar house that works
well on an average day can shoot itself in the foot over a few cloudy days.
>...i have an rs-232-ported dmm from radio shack, with accompanying
>software for logging (do i need the data logger?) and am wondering:
>a) for how long the edmund scientific... photodiode... should be
>utilized for useful data
nrel used 30 years, 1961-1990 :-) then again, things may have changed
with global warming.
>b) if i could simply use us data from say, maine at similar latitude
nrel only lists caribou (too cold) and portland, which is sunnier and
colder than halifax, with 940 btu/ft^2 on a south wall on an average
26.6 f december day. you might use a portland tmy2 file and add 30-26.6
degrees and reduce the sun by a factor of 523/940...
>c) what's this about the nrc of canada/fahrenheit 451??
i've heard this story from two people who were deeply involved. it seems
that some part of the canadian government worried that this 1981 solarium
program was becoming so popular that people might need a lot less government
help with their energy problems, so they cancelled the program at brace
research institute at mcgill u at ste. anne de belle vue near montreal and
ordered brace to stop printing the workbooks and ordered all existing copies
in english and french destroyed. you might still find one in a library.
i have a copy that was rescued from a loading dock by one of these people,
who managed to carry away a car trunkful before the rest were destroyed :-)
with further investigation (a lot of talking with people in ottowa), this
might make an interesting muckraking magazine or newspaper story. let me
know if you'd like more details...
tired of iraq? do something about it. learn to halve your energy use
while having fun with math and science.
join solar guru steve baer and pe drew gillett and phd rich komp and
me for an all-day workshop on solar house heating and natural cooling
strategies ("hvac nonsense") on july 9 in portland, or--see page 25 of