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Jon,
SkyCalc is simple to use tool to look at daylighting potential from
skylights and daylight harvesting controls potentials. SkyCalc is an Excel
spreadsheet that uses preprocessed DOE-2 hourly outputs to generate energy
savings estimates for different fractions of roof area covered with skylights
and under different lighting control strategies.
SkyCalc is free and is available with climate specific "weather files"
for 34 locations. SkyCalc can be downloaded from www.h-m-g.com.
Jon McHugh, PE, LC
Heschong Mahone Group
11626 Fair Oaks Blvd #302
Fair Oaks, CA 95628 (Sacramento)
(916)962-7001
(916)962-0101 FAX
e-mail: mchugh@xxxxxxxxx
URL: www.h-m-g.com
I wanted to compare FPS plots against
radiation plots so I could learn more about their correlation (or lack
thereof) in different locales. I planned to use one or the other to
help me get a sense for possible regional variation
in daylighting/dimming controls savings potential. I had a lot
easier time finding radiation data, if it is any consolation to you in
your mission, Chip. but I thought sunshine data would be better to use if
available. Tabular data is better for quantitative analysis of course,
but I wanted to see pictures.
FYI two good sources for solar radiation
plots are:
for an
annual plot (attractive training illustration),
for
monthly plots by various orientations ( a better analytical
tool).
Not to be too contrary but I spot-checked
the tabular data from the source in my original email with the homepower map
above and the general patterns do seem to correlate pretty well.
Finally, for those of you that are interested,
Jeff Haberl responded to me directly with a FPS resource: "I believe that there is a map on Kreith
and Kreider's Solar energy handbook...that shows this for the world...using the
Angstrom-Lof minutes of sunshine." Thanks to
Jeff.
----- Original Message -----
Sent: Wednesday, September 26, 2001 9:12 AM
Subject: Re: [BLDG-SIM] Fraction of Possible Sunshine
Jon --
I don't know of a
source for a map, but I do have a question ... what do you want it
for?
I am trying to learn how people use this statistic. It has
been traditionally observed, so people keep observing it. I am involved
in work on ASHRAE TC 4.2 (Weather Information) that is developing methods for
extracting solar radiation from weather data measured by ASOS (Automated
Surface Observation System) now used to observe weather at most sites in the
US. ASOS has planned to add sunshine meters to their machines (that plan
is now delayed due to funding), but it would be just about as easy, and much
more useful (in our opinion) to measure solar radiation. Sunshine
fraction is a notoriously bad predictor of solar radiation (the correlations
are pretty poor). With trivial data processing, minute-by-minute solar
radiation data can be used to estimate sunshine, but not
vice-versa.
Thus as far as I know the solar and building simulation
community has no use for sunshine data -- the statistic should be declared
obsolete from our point of view. However, at every opportunity, I try to
find why people want it, there may be some other uses that we don't know
about.
So, if you're willing, please let me know what you're up
to.
To the rest of BLDG-SIM: anyone else know of uses for sunshine
fraction?
Thanks, Chip Barnaby
Does anyone
out there have or know of a source for a graphical illustration of Fraction
of Possible Sunshine over the U.S. I found a very good table of such
data at http://cdiac.esd.ornl.gov/ftp/ndp021/
(file #12), but haven't had any luck with a map. Thanks in
advance.
Jon Maxwell,
PE
Aspen Systems Corp.
jmaxwell@xxxxxxxxxxxx
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---------------------------------------------------------
Chip
Barnaby
cbarnaby@xxxxxxxxxxxxxx
Vice President of Research
Wrightsoft
Corp.
781-862-8719 x118 voice
394 Lowell St, Suite
12 781-861-2058 fax
Lexington, MA
02420 www.wrightsoft.com
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