<div dir="ltr">Thank you all for replying! <div><br></div><div>Your answers gave me the information I needed. </div><div><br></div><div>I appreciate your help!</div><div><br></div><div>Best Regards</div><div>Ida Auråen</div>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">2013/5/24 Jeffrey D. Spitler <span dir="ltr"><<a href="mailto:spitler@okstate.edu" target="_blank">spitler@okstate.edu</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<div>Ida,<br>
It has been probably 10 years since I looked at the esp-r surface
heat balance and transient conduction routines for the surrounding
ground. But, at that time, the answer was "no" - it did not
model the effects of snow by either changing the reflectivity of
the surface or by accounting for the insulating effect of snow. I
strongly suspect this is the case for most or all other building
simulation tools. <br>
<br>
If you are only interested in getting an answer for a particular
building in a particular location, you can STOP READING HERE and
hope that someone else will give you some more useful advice!
But, since I am involved in related research, I have a few
thoughts on the matter...and am always interested to find out that
I have missed some published work in the area, don't know about an
unpublished technique or method, there is a better way to do it; I
am plain wrong, etc.! <br>
Then, from my perspective, the basic issues are:<br>
<br>
(1) You need to have weather data that would support this kind of
calculation. I have looked at a lot of the EnergyPlus weather
files for the USA and while there are fields for precipitation, in
many cases they just have zero values. On the other hand, I think
you mentioned Östersund in an earlier message - I checked the
IWEC-2 data file for Östersund and it does have precipitation
depth in liquid equivalents, including values for hours that are
below freezing. With that, it would at least be possible to
estimate when you have snow fall. <br>
<br>
I suspect one reason for the paucity of freezing precipitation
data is that you need a heated rain gauge to measure precipitation
"correctly" in sub-freezing conditions; heating the rain gauge can
introduce other errors; at least here, automated surface
observation stations tend not to have heated rain gauges because
of the power requirements. That doesn't explain why there is a
shortage of any precipitation data in weather files here in the
USA, though.<br>
<br>
(2) From an energy calculation standpoint, a typical snowfall year
is problematic for calculating heat loss from the basement or
foundation. In many locations, a year with an early snowfall will
have much different ground heat transfer than a year with a late
snowfall. This seems to be highly random for many locations.<br>
<br>
(3) To automatically predict, in a building simulation tool, when
you would have snow and how much snow would be present and what
its insulating value would be, you would need a full snow
accumulation/melting model. We have done this for bridge deck
snow melting systems:<br>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span>Liu, X., S.J.
Rees and J.D. Spitler. 2007. <i>Modeling
Snow Melting on Heated Pavement Surfaces Part I: Model
Development</i>. Journal
of Applied Thermal Engineering. 27:1115-1124. <u></u><u></u></span></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span>Liu, X., S.J.
Rees and J.D. Spitler. 2007. <i>Modeling
Snow Melting on Heated Pavement Surfaces Part II:
Experimental Validation</i>.
Journal of Applied Thermal Engineering. 27:1125-1131.<u></u><u></u></span></p>
and then later applied it to look at what is needed for prediction
of undisturbed ground temperatures; I view this as a precursor to
predicting disturbed ground temperatures - the issues are
basically the same, though we found that disturbed ground
temperatures could also be influenced by shading from the building
in some of our work related to foundation heat exchangers:<br>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span>Xu, H. and
J.D. Spitler. 2011. <i>Importance
of
moisture transport, snow cover and soil freezing to ground
temperature
predictions.</i> Proceedings of the Nordic Symposium on
Building Physics. May
2011.<br>
</span></p>
(I should also note that we found freezing and thawing in the
ground to be important.) Modeling of snow accumulation and
melting is computationally demanding and would take some time to
implement in any building simulation program. It may well be that
some clever individual has developed an approximate algorithm that
is faster and "good enough". If so, I would be quite interested
to hear about it. <br>
<br>
I am also very interested to hear if anyone else is involved in
related research. Ida - I am sorry not to have a more immediately
helpful answer.<br>
<br>
Best wishes,<br>
Jeff Spitler<div><div class="h5"><br>
<br>
<span><u></u><u></u></span><br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
On 5/24/2013 7:41 AM, Ida Auråen wrote:<br>
</div></div></div>
<blockquote type="cite"><div><div class="h5">
<div dir="ltr">
<p style="margin-bottom:0.0001pt"><span style="font-size:12pt;font-family:Arial,sans-serif" lang="EN-US">Hi, </span><span style="font-size:12pt;font-family:'Times New Roman',serif" lang="EN-US"></span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt">I have a
question regarding climate file and snow.</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt">If you
are modeling a building in a cold climate
where there is snow lying on the ground a significant time
of the year, will
ESP-r take this into account?</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt">Snow
will insulate the ground and minimize the
depth of frozen ground. The snow will also reflect solar
radiation well and it will
contribute to more passive solar heat through windows or to
solar collectors/pv-panels.</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt">Is there
snow on the ground for the simulations
done in ESP-r in colder climates?</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt"><br>
</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-family:Arial,sans-serif;font-size:12pt">Best
Regards</span></p>
<p style="margin-bottom:0.0001pt"><span style="font-size:12pt;font-family:Arial,sans-serif" lang="EN-US">Ida Auråen</span><span lang="EN-US"></span></p>
</div>
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<pre cols="72">--
Jeffrey D. Spitler, PhD, PE
Regents Professor and C.M. Leonard Professor
School of Mechanical and Aerospace Engineering
Oklahoma State University
<a href="http://www.hvac.okstate.edu" target="_blank">http://www.hvac.okstate.edu</a>
Ofc: <a href="tel:405-744-6578" value="+14057446578" target="_blank">405-744-6578</a></pre>
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