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<p>I think my previous response was a tad short, so I'll elaborate
:-) (What actually happened was that I was composing my answer
on my IPhone that sent it out unexpectedly, so I decided to wait
until I got to the office where I'm in more control of the
e-mail).</p>
<p>Chris,</p>
<p>Yes, you're correct on both points. The percentiles are of all
the hourly values in the long-term record, so 0.4% would mean
there are on average 35 hours at or above that temperature over a
year, and so forth. The pre-1996 definition of 1% seasonal would
be 22 hours at or above that temperature over 2208 hours from June
through August. If all the hours above that temperature would
occur only in those three summer months, the 1% seasonal would
correspond to 0.25% annual. However, there are almost always
such hours that occur outside of those months and since the
frequency of occurrence varies greatly by climate, it's
impossible to find an universal correspondence of annual to
seasonal frequencies. For example, in Singapore where there is
very little season variation in temperatures, the 1% seasonal
would be about the same as the 1% annual, or 88 hours over a
typical year, more than double the number of hours in a temperate
climate. Because of these inconsistencies and the awkwardness of
having to define summer and winter in different locations (here in
San Francisco the hottest month is always September), ASHRAE
decided to change from seasonal to annual percentiles for the 1997
Handbook. I was on TC 4.2 at the time, and what transpired with
this switch was interesting and at times humorous. If we switch
to annual percentiles, which percentiles should we use? Engineers
are very attuned to "their" design temperatures, so we didn't want
to create an uproar with large changes in the design temperatures
due to changes in the metric, but new metric does not produce a
one-to-one correlation to the old metric. In the end, the TC asked
the contractor to compare the temperatures at different annual
percentiles to the old seasonal percentiles, and use the annual
percentiles with the best overall match, which turned out to be
0.4%, 1%, and 2% for the previous 1%, 2.5% and 5% seasonal
percentiles. <br>
</p>
<p>There are many things in the ASHRAE design procedure that are
similarly ad-hoc or evolutionary, to use a better adjective :-) ,
which is why I tend to view it with a slight grain of salt. I've
also talked to engineers and academics in other countries over the
years, and have that the ASHRAE design procedure is only one of
several in the world.<br>
</p>
<p>Joe</p>
<pre class="moz-signature" cols="90">Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
<a class="moz-txt-link-abbreviated" href="mailto:yjhuang@whiteboxtechnologies.com">yjhuang@whiteboxtechnologies.com</a>
<a class="moz-txt-link-freetext" href="http://weather.whiteboxtechnologies.com">http://weather.whiteboxtechnologies.com</a> for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
</pre>
<div class="moz-cite-prefix">On 6/8/2019 5:03 PM, Joe Huang wrote:<br>
</div>
<blockquote type="cite"
cite="mid:DA043451-5ABD-4D90-B475-5BF8F042B2E5@whiteboxtechnologies.com">The
1%, 99% used prior to <br>
<br>
<div id="AppleMailSignature" dir="ltr">Sent from my iPhone
<div>Joe Huang</div>
<div>White Box Technologies</div>
<div>346 Rheem Blvd Suite 108D</div>
<div>Moraga CA 94556</div>
<div>(o) 1(925)388-0265</div>
<div>(c) 1(510)928-2683</div>
<div><a href="mailto:yjhuang@whiteboxtechnologies.com"
moz-do-not-send="true">yjhuang@whiteboxtechnologies.com</a></div>
</div>
<div dir="ltr"><br>
On Jun 8, 2019, at 3:58 PM, Dru Crawley <<a
href="mailto:dbcrawley@gmail.com" moz-do-not-send="true">dbcrawley@gmail.com</a>>
wrote:<br>
<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="auto">1 percent of 8760 = 87.6</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Jun 8, 2019, 6:03
PM Chris Yates via Bldg-sim <<a
href="mailto:bldg-sim@lists.onebuilding.org"
moz-do-not-send="true">bldg-sim@lists.onebuilding.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote">
<p dir="ltr">Thanks Joe. This is fascinating. </p>
<p dir="ltr">My understanding of the percentiles 0.4, 1.0,
99 & 99.6% design data was that they covered
everything except the coldest or hottest 35 or 87.6
hours in a typical year. I need to double check my
understanding. All I know is that it seems to work the
opposite way around if I use Excel's PERCENTILE.INC
function! </p>
<p dir="ltr">Was the translation of the 1% to 0.4% based
on the former being two seasons?</p>
<div class="gmail_quote">On 7 Jun 2019 21:20, "Michael J
Witte via Bldg-sim" <<a
href="mailto:bldg-sim@lists.onebuilding.org"
target="_blank" rel="noreferrer"
moz-do-not-send="true">bldg-sim@lists.onebuilding.org</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote">
<div> Thanks Joe - I was hoping someone would chime in
with more authority. And a fascinating personal
history - who knew?<br>
<br>
<div>On 6/7/2019 2:36 PM, Joe Huang via Bldg-sim
wrote:<br>
</div>
<blockquote type="cite"> As the current chair of TC
4.2 Climatic Information, I feel obligated to
reply :-)
<div>
<p>While I admire Chris' and your enthusiasm, I
am pretty certain that the design temperatures
in the ASHRAE Handbook grew out of the needs
of the HVAC engineers going back at least to
the 1940's for cooling, and even much earlier
for heating. I'm hoping that Jeff Haberl can
clarify the situation and have cc'd him on
this e-mail to get his attention. I've also
cc'd the TC4.2 Group in case others remember
more clearly the history of ASHRAE design
temperatures. If I were a betting man, I would
wager the HOF design temperatures came out of
either the industry (Carrier ?) or engineers
within the predecessor societies AHVE, ASHE
that merged in 1959 to form ASHRAE, and that
the Air Force adopted it in their
publication, rather than the other way around.
As Michael had pointed out, the AF publication
states that the design temperatures were
"intended to support design and construction
of DOD facilities", with no mention of use in
military aviation. <br>
</p>
<p>It's funny how this almost off-the-cuff
decision had endured and got embellished to
make it seem more hefty. For example, in the
1960's engineers got concerned about dynamic
effects and so added on hourly profiles for
temperature, solar, wind, etc., to create an
artificial design day, and in the 1990's to
accommodate climates with different seasons
(or no seasons!) the criteria was switched
from a seasonal 1% to an annual 0.4%. Why
0.4% ? Simply because the temperatures would
match the previous 1% seasonal (I was in TC
4.2 at the time and recalled those
discussions). The evolution of ASHRAE Design
Conditions would seem also to make an
interesting and informative paper.</p>
<p>As far as meteorology having an impact on
military operations, I can describe an old
family story. My father, <a
href="https://www.gettyimages.co.uk/photos/irving-p.-krick-dr.-hsia-chien-huang?sort=mostpopular&mediatype=photography&phrase=irving%20p.%20krick%20dr.%20hsia%20chien%20huang&license=rf,rm&page=1&recency=anydate&suppressfamilycorrection=true"
target="_blank" rel="noreferrer"
moz-do-not-send="true">Dr. Hsia-Chien Huang</a>,
was the Chief Meteorologist of China during
World War Two. He received his Ph.D. at
Caltech in the late 1930's studying with <a
href="https://en.wikipedia.org/wiki/Irving_P._Krick"
target="_blank" rel="noreferrer"
moz-do-not-send="true">Dr. Irving Krick</a>.
Dr. Krick was hired by General Eisenhower to
forecast the weather for the Normandy
Invasion. The details are in the web page so I
won't describe them here, only to say that I
grew up hearing that Dr. Krick predicted the
weather for the invasion and that someone in
the UK actually produced a play about this
incident. Since Dr. Krick sponsored my family
to the US in 1955, I can say that the only
reason I'm in the US is due to meteorology!
For the oldtimers in TC 4.2, can you guess who
picked up my family when we arrived in Denver
64 years ago? Loren Crow, who was then
working for Dr. Krick, as did my father
afterwards. Loren was very involved in TC 4.2
up until the early 1990s, having created the
original WYEC files and the CTZ files for
California. Gee, maybe all these deep
personal connections to meteorology might
explain my late life pre-occupation with
weather data!<br>
</p>
<p>Joe<br>
</p>
<div>On 6/7/2019 7:05 AM, Michael J Witte via
Bldg-sim wrote:<br>
</div>
<blockquote type="cite"> Chris - Sure, go right
ahead and write a joint article for CIBSE and
ASHRAE.<br>
<br>
I know ASHRAE is working on interviewing those
with a long-time perspective (old-timers) to
document early ASHRAE work.<br>
Jeff H - anything related to weather data
happening in the history effort? Maybe some
members of the weather data TC would
contribute.<br>
<br>
Linda - Does the forward of Engineering
Weather Data have any mention of the
motivation for that data? Is that where the
concept of using 99% etc. was first used?<br>
<br>
Anyone out there have a copy of the Fluor
Products publication? It was cited as the
source of the US design data in the 1972 HOF.<br>
Evaluated Weather Data For Cooling Equipment
Design, Addendum No. 1, Summer and Winter Data
(Fluor Products Company, Santa Rosa, Calif.,
1964).<br>
<br>
<div>On 6/6/2019 8:30 AM, Linda Lawrie wrote:<br>
</div>
<blockquote type="cite"> I have a copy of the
Engineering Weather Data document (1978
version). (Thanks, Bob H). <br>
<br>
And many other historical "weather data"
documents though not sure how many discuss
heating/cooling design data.<br>
<br>
Linda<br>
<br>
At 04:32 AM 6/6/2019, Chris Yates via
Bldg-sim wrote:<br>
<br>
<blockquote type="cite">Wow. You know what
Michael. I think you have the makings of
an ASHRAE journal atricle! I want to do
something similar for CIBSE. I'd love to
use your findings. <br>
On 5 Jun 2019 23:21, "Michael J Witte via
Bldg-sim" <<a
href="mailto:bldg-sim@lists.onebuilding.org"
target="_blank" rel="noreferrer"
moz-do-not-send="true">
bldg-sim@lists.onebuilding.org</a>>
wrote:<br>
<dl>
<dd>I haven't seen a reply yet to this,
so here goes . . .<br>
<br>
</dd>
<dd>The oldest ASHRAE handbook on my
shelf is a 1972 HOF (thanks Bob H.!).
Chapter 33 is Weather Data and Design
Conditions. The reference list
includes these two primary sources:<br>
<br>
</dd>
<dd>Evaluated Weather Data For Cooling
Equipment Design, Addendum No. 1,
Summer and Winter Data (Fluor Products
Company, Santa Rosa, Calif., 1964).<br>
</dd>
<dd>and<br>
</dd>
<dd>Engineering Weather Data (Army,
Navy, and Air Force Manual TM 5-785,
1963).<br>
<br>
</dd>
<dd>You can buy a copy of the 1958
edition of Evaluated Weather Data on
amazon<br>
</dd>
<dd> <a
href="https://www.amazon.com/Evaluated-Weather-Cooling-Equipment-Design/dp/B000HDSNFY"
target="_blank" rel="noreferrer"
moz-do-not-send="true">
https://www.amazon.com/Evaluated-Weather-Cooling-Equipment-Design/dp/B000HDSNFY</a>
<br>
<br>
</dd>
<dd>I bet someone out there has a copy
of the Engineering Weather Data manual
on a shelf. Some quick searching leads
to this later online version.<br>
</dd>
<dd> <a
href="http://web.utk.edu/~archinfo/EcoDesign/escurriculum/weather_data/weather_data_summ.html"
target="_blank" rel="noreferrer"
moz-do-not-send="true">
http://web.utk.edu/~archinfo/EcoDesign/escurriculum/weather_data/weather_data_summ.html</a>
<br>
</dd>
<dd>which says:<br>
<br>
</dd>
<dd>"The Engineering Weather Data (EWD)
and other products were developed by
the Air Force Combat Climatology
Center (AFCCC). Data is provided for
approximately 800 stations worldwide.
Intended to support design and
construction of DOD facilities, the
format is slanted toward professional
engineers, but could have numerous
other uses. "<br>
<br>
</dd>
<dd>Searching AFCCC leads here to a
fascinating history.<br>
</dd>
<dd><a
href="https://www.airweaassn.org/Library/afwa/history.html"
target="_blank" rel="noreferrer"
moz-do-not-send="true">
https://www.airweaassn.org/Library/afwa/history.html</a><br>
<br>
</dd>
<dd>"The mission of AFCCC is one of
military applied climatology. We
collect, maintain, and apply worldwide
weather data, creating climatological
products to strengthen the combat
capability of America's warfighters.
AFCCC's support to America's
warfighters has a long history."<br>
<br>
</dd>
<dd>And a fitting excerpt on the 75th
anniversary of D-Day:<br>
<br>
</dd>
<dd>"There was probably no WWII
operation, major or minor, that did
not include climatological input. The
planning for every landing, mission,
and offensive, including the D-Day
invasion in 1944 and the atomic
bombing of Japan, required extensive
climatological preparation and
analyses."<br>
<br>
</dd>
<dd>So, Chris, your impression appears
correct. Weather data statistics were
motivated by military requirements
(for better or worse), and marketing
cooling equipment.<br>
<br>
</dd>
<dd>Mike<br>
<br>
</dd>
<dd>p.s. The pages from the 1972 HOF are
included in a digitized NBSLD manual
(one of the great mother programs of
building simulation), pdf p. 287ff.<br>
</dd>
<dd> <a
href="https://www.govinfo.gov/content/pkg/GOVPUB-C13-9bcc6856169c63cf2c5ab81af189bd75/pdf/GOVPUB-C13-9bcc6856169c63cf2c5ab81af189bd75.pdf"
target="_blank" rel="noreferrer"
moz-do-not-send="true">
https://www.govinfo.gov/content/pkg/GOVPUB-C13-9bcc6856169c63cf2c5ab81af189bd75/pdf/GOVPUB-C13-9bcc6856169c63cf2c5ab81af189bd75.pdf</a>
<br>
<br>
<br>
<br>
</dd>
<dd>On 5/20/2019 4:16 AM, Chris Yates
via Bldg-sim wrote:<br>
<blockquote type="cite"> <dd>Hi All <br>
<br>
</dd>
<dd>Does anybody have any
interesting background on the
sources of (and motivations for
calculating) the outdoor design
conditions now available in ASHRAE
HOF?<br>
<br>
</dd>
<dd>My impression is that it was
possibly derived for the purposes
of keeping B52's and allied
v-bombers ready for action at a
moment's notice.<br>
<br>
</dd>
<dd>Cheers<br>
<br>
</dd>
<dd>Chris<br>
<br>
<br>
</dd>
<dd>
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