Thank you both Andrew and Keith,<br><br>Understanding the exceptions, and also correct calculations for the EER (didn't realize there was a limit of 15,000 BTU for the calculation until I read the small print!) are very helpful. It brings up another question, now, though: <br>
<br>When modeling a PTAC unit, and taking this EER value, would you use this to include the supply fan energy? G.3.1.2.1 states that you should separate it into various components, which confuses me a bit. I know this is getting down to minutia, however, just trying to make sure I'm doing this correctly. If this is something that is common practice to look over, and just make sure to include the supply fan efficiencies within the EER for entire unit (something that would make sense to me as it is a packaged unit), also let me know.<br>
<br>Thanks again,<br><br>Loren<br><br><div class="gmail_quote">On Mon, Mar 10, 2008 at 6:35 PM, Keith Swartz <<a href="mailto:kswartz@ecw.org">kswartz@ecw.org</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Loren,</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">One of the notes under Table G3.1.1A of
ASHRAE 90.1-2004 states, "Residential building types include dormitory,
hotel, motel, and multifamily. Residential space types include guest rooms,
living quarters, private living space, and sleeping quarters. Other building
and space types are considered nonresidential." The User's Manual
also says, "If a building has both residential and nonresidential spaces,
for instance a residential tower with retail and restaurants at the base, then
the HVAC system type is determined separately for the residential and
nonresidential portions."</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">I recently did an energy model for a motel
that had first floor retail spaces, a swimming pool, an indoor parking garage,
and a fairly large lobby. I used realistic systems for these spaces instead of
PTACs or PTHPs. For a different motel I modeled, the nonresidential spaces were
rather insignificant, so I used PTHPs throughout.</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Regarding which capacity to use for the
EER calculation, I would use realistic capacities. For example, for the space
that needs 40 kBTU/h, I would assume that there would be two 20 kBTU/h units
and use 20 kBTU/h for the capacity in the EER equation.</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">I think the decision to use an average EER
for all the units is a judgment call depending on how complex you want your
model to be. It's the usual trade-off between making assumptions to
simplify the model or adding complexity to get more accuracy (presumably).</span></font></p>
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<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Sincerely,</span></font></p>
<p><font color="navy" face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial; color: navy;">Keith Swartz, PE, LEED® AP</span></font></p>
<p><font face="Arial" size="2"><span style="font-size: 10pt; font-family: Arial;"><font color="navy"><span style="color: navy;">Energy</span></font><font color="navy"><span style="color: navy;"> </span></font><font color="navy"><span style="color: navy;">Center</span></font><font color="navy"><span style="color: navy;"> of </span></font><font color="navy"><span style="color: navy;">Wisconsin</span></font><font color="navy"><span style="color: navy;"></span></font></span></font></p>
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<p><b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font face="Tahoma" size="2"><span style="font-size: 10pt; font-family: Tahoma;"> Loren Appin
[mailto:<a href="mailto:lorenappin@gmail.com" target="_blank">lorenappin@gmail.com</a>] <br>
<b><span style="font-weight: bold;">Sent:</span></b> Sunday, March 09, 2008 3:31
AM<div class="Ih2E3d"><br>
<b><span style="font-weight: bold;">To:</span></b> <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
<b><span style="font-weight: bold;">Subject:</span></b> [Bldg-sim] Residential or
Nonresidental? And sizing for PTAC units.</div></span></font></p>
</div><div class="Ih2E3d">
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<p><font face="Times New Roman" size="3"><span style="font-size: 12pt;">Hi All,<br>
<br>
I'm modeling a 6 story hotel, and am confused with how I should classify the
building. The hotel is all guest rooms, and is not really mixed
use. So according to ASHRAE this seems that it would fall under the
residential category, and I would be using PTAC or PTHP systems. Under
table G3.1.1A it specifically says hotels are considered residential building
types, not just space types... so I assume I'm correct? However,
would I use a VAV or PSZ system for areas that are not technically guest rooms,
or does this not matter as a hotel is considered a residential "building
type"?<br>
<br>
<br>
Also, when modeling a PTAC system it appears to me that you would get the EER
information from 6.8.1D using the equation, however, sometimes it my system
summary gives me a peak/capacity of a unit as 30KBtu or even 40 for one room
and I know that PTAC units usually don't go much about 20. So would the
equation in this table still hold? Finally, if I am getting varying
capacities for each unit as would be expected, would you suggest taking an
average of all the systems, and then use this capacity as the one to enter into
the equation to get the EER and then apply this EER to all systems across the
board?<br>
<br>
Thanks so much for the help!<br clear="all">
</span></font></p>
<p style="line-height: 150%;"><b><font face="Arial" size="2"><span style="font-size: 10pt; line-height: 150%; font-family: Arial; font-weight: bold;">Loren Appin</span></font></b></p>
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