<div><div dir="auto">My personal opinion is that while TMYs are nice, given computing power available today and the new problems we are going to need to solve, where the value of energy changes by orders of magnitude and extreme conditions matter, we should be considering running with many years of weather data instead. I’ve had some projects where we did this, but my business is all about grid impacts of aggregations of buildings, which is a little different use case than most. My sense is that you generally work with TMY and then move to running the weather decades and perhaps then focusing on the weather year with your design shortage condition, before returning to the weather decades. Maybe we will still slice 2020 out, just because. </div></div><div dir="auto"><br></div><div dir="auto">Happy holidays!</div><div><br><div class="gmail_quote"><div dir="ltr">On Thu, Dec 24, 2020 at 6:46 AM Joe Huang via Bldg-sim <<a href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<p>:-)</p>
<p>Presenting metadata or applying checksums would pick out
arithmetic or unit errors like what happened in the original
TMY3s, but better documentation of the data and their provenance
is the key to making sense of a weather file. This thread has
been talking about mistakes in the TMY3s, but I give credit to
NREL for developing the TMY2/TMY3 format that added flags to every
data element and included the actual time stamp. <br>
</p></div><div>
<p>Joe<br>
</p>
<pre cols="90">Joe Huang
White Box Technologies, Inc.
<a href="https://www.google.com/maps/search/346+Rheem+Blvd.,+Suite+205A%0D%0AMoraga+CA+94556?entry=gmail&source=g">346 Rheem Blvd., Suite 205A
Moraga CA 94556</a>
<a href="mailto:yjhuang@whiteboxtechnologies.com" target="_blank">yjhuang@whiteboxtechnologies.com</a>
<a href="http://weather.whiteboxtechnologies.com" target="_blank">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>On 12/24/2020 3:28 AM, Chris Yates
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Like glazing, I'm often a bit lost when it comes to rooting
out the right weather file. In one instance, this has even led
to purchasing the same data twice from CIBSE!</div>
<div><br>
</div>
I've thought that either better presentation of metadata or
applying checksums to weather files could get around this.
<div><br>
</div>
<div>Chris</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Dec 22, 2020 at 1:11
AM Joe Huang via Bldg-sim <<a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>I forgot to mention as an aside I noticed that NREL had
taken the (revised) TMY3 files offline several months
ago. However, these TMY3s in EPW and BINM formats are
still available on my Web site at <a href="http://weather.whiteboxtechnologies.com/TMY3" target="_blank">weather.whiteboxtechnologies.com/TMY3</a>.
I'm also in the process of adding the *.CSV format to the
files now that they're gone from the NREL Web site.</p>
<p>Joe<br>
</p>
<pre cols="90">Joe Huang
White Box Technologies, Inc.
<a href="https://www.google.com/maps/search/346+Rheem+Blvd.,+Suite+205A%0D%0AMoraga+CA+94556?entry=gmail&source=g">346 Rheem Blvd., Suite 205A
Moraga CA 94556</a>
<a href="mailto:yjhuang@whiteboxtechnologies.com" target="_blank">yjhuang@whiteboxtechnologies.com</a>
<a href="http://weather.whiteboxtechnologies.com" target="_blank">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>On 12/21/2020 3:55 PM, Joe Huang wrote:<br>
</div>
<blockquote type="cite">
<p>Interesting to see my work described by someone who was
never involved. The original driver for doing that work
was to correct the decimal mistake in some of the
illuminance data that NREL had noted in 2005 but never
corrected because the original developers had retired.
The reporting of precipitation was an additional
improvement I offered to NREL, and actually ended up the
lion's share of the work because it required
reprocessing all the source weather files. Neither of
these corrections/improvements should affect any other
weather set developed from scratch. i have always been
careful to not infringe on NREL's branding of TMY for a
number of reasons, one of which has just been shown that
all TMYs are assumed to be related.<br>
</p>
<p>Joe<br>
</p>
<pre cols="90">Joe Huang
White Box Technologies, Inc.
<a href="https://www.google.com/maps/search/346+Rheem+Blvd.,+Suite+205A%0D%0AMoraga+CA+94556?entry=gmail&source=g">346 Rheem Blvd., Suite 205A
Moraga CA 94556</a>
<a href="mailto:yjhuang@whiteboxtechnologies.com" target="_blank">yjhuang@whiteboxtechnologies.com</a>
<a href="http://weather.whiteboxtechnologies.com" target="_blank">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>On 12/21/2020 3:04 PM, Linda Lawrie via Bldg-sim
wrote:<br>
</div>
<blockquote type="cite"> <font size="3">the TMY3 files on
<a href="http://climate.onebuilding.org" target="_blank">climate.onebuilding.org</a>
have been corrected from the document posted by Joe
Huang on the tmy3 site. But I think that was for
precipitation.<br>
<br>
the TMYx files would never have had this problem as
they come from a different source of our creation for
the TMYx files.<br>
<br>
And, as I remember, the illuminance problem was
corrected by NREL at some point after their first
post.<br>
<br>
------<br>
Linda<br>
<br>
FIBPSA, FASHRAE<br>
<a href="http://climate.onebuilding.org/" target="_blank">
http://climate.onebuilding.org</a> - free repository
of climate data for building simulation<br>
Climate.onebuilding is a FREE service not supported by
any outside organization or government agency. <br>
<br>
<br>
<br>
</font>
<blockquote type="cite"><font size="3">Does anyone know
if the errors described in TMY3 files in this post
from Joe Huang on Jan 14 2015 still exist in files
on the <a href="http://climate.onebuilding.org/" target="_blank">
http://climate.onebuilding.org/</a> website? And
were these errors also fixed in TMYx files?<br>
<br>
Specifically I’m interested in this issue:<br>
<br>
<br>
1) Illuminance. The TMY3s contain values for Global
Horizontal, Direct Normal, Diffuse<br>
Horizontal, and Zenith Illuminance that are
calculated based on the sun position and solar<br>
radiation. Although the documentation states that
the units are 100 lux for the first<br>
three illuminances, and 10 candela/m2 for the Zenith
Illuminance, all the TMY3 files used<br>
these units only for the period Jan. 2-31, and for
the rest of the year used units of lux<br>
and candela/m2, respectively. NREL put out a notice
in August 2008 (see the link listed<br>
earlier) informing users of this discrepancy and
promising a corrected version that didn't<br>
make it out until now! In this revision, we've
decided to keep the units in the original<br>
TMY3 documentation, i.e., 100 lux or 10 candela/m2,
which is the same as what was in the<br>
TMY2, and avoids the superfluous five-digit
precision.<br>
<br>
If I use a TMY3 or TMYx file from the <a href="http://climate.onebuilding.org" target="_blank">climate.onebuilding.org</a>
website, am I getting a TMY3 or TMYx version in
which these issues are corrected?<br>
</font></blockquote>
<br>
<fieldset></fieldset>
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