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Zhou,<br>
I don't think you've done anything incorrect in your project. I
think there are a few reasons for your low cooling load.<br>
<br>
1. there is only one window in the building allowing solar heat
gains into the space.<br>
2. the internal gains (equipment, lighting) are very small (50W in
the sun and back zones). This means that the building internal
temperature isn't being driven up by much.<br>
3. the floor slab is uninsulated and coupled directly to a constant
10C temperature all year round (this provides some free cooling).<br>
4. all three zones have 0.5 airchanges per hour of infiltration
(ambient air). While that is not unreasonable, infiltration
typically increases heating loads and decreases cooling loads.<br>
<br>
I would also recommend raising the zone thermal capacitance values
to 5 times their default. The default accounts only for the thermal
capacitance of the air in the zone. It neglects the capacitance of
the furnishings. I would also recommend setting the humidity
capacitance multiplier to 10 instead of 1; a value of 1 indicates
that only the air in the zone has any ability to absorb and desorb
moisture. These will have secondary effects on your cooling load.<br>
<br>
Regards,<br>
David<br>
<br>
<br>
On 11/8/2010 06:56, jw_zhou wrote:
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<div><font face="Verdana" size="2">dear sir,</font></div>
<div> </div>
<div>I send files of "***.tpf" and "***.bui" to you for your help
to find out why the sensible cooling energy demand is so small
and much smaller than sensible heating energy demand. For you
quick understand of my projrct, some brief information about the
project are listed below:</div>
<div> </div>
<div>1. there are three zone from south to north, the sunzone is
face to south, the backzone to north, and the midzone, which is
modeled as the hall way, is adjacent to both the sunzone and
backzone. all of the zones have same size and 48m^2.</div>
<div> </div>
<div>2. I want to get the building load of the sunzone, so I added
an internal heating(set points=20℃) and cooling（set
points=27℃), also add a ventilation type--newwind which air
chang rate is 0.6 per hour. </div>
<div> </div>
<div>3. the main outputs of sunzone are NTYPE1, 10，30, 31 which
are zone air temperarue(℃), latent energy demand(W/m^2),
sensible cooling energy(W/m^2), sensible heating energy(W/m^2).
</div>
<div> </div>
<div>4. According to results, there are two unreasonable points:
heating load is much larger the cooling load; the latent energy
damand had taken a large part of whole cooling load. would I
omited something or these results are right?</div>
<div> </div>
<div>hope for your reply, and thank you very much.</div>
<div><font color="#c0c0c0" face="Verdana" size="2">2010-11-08 </font></div>
<font face="Verdana" size="2">
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<div><font color="#c0c0c0" face="Verdana" size="2"><span>jw_zhou</span>
</font></div>
</font>
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<pre class="moz-signature" cols="72">--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI 53703 USA
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F:+1.608.278.1475
<a class="moz-txt-link-abbreviated" href="mailto:d.bradley@tess-inc.com">d.bradley@tess-inc.com</a>
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