<div>You need to have some mechanism for passively charging your mass to really get the major energy benefits of the mass. If you have a building that's being actively heated and cooled all the time, with no passive inputs, then the mass won't do much except reduce your peak thermal load some, provided you get an actual temperature differential between the mass and the space (i.e. the system is sized correctly and the space temperature exceeds the typical set point at the peak hour). </div>
<div> </div>
<div>So, you can couple passive solar input to your mass, and use that mass to sink heat for later (rather than having the space temperature rise). The passive solar input to the space has to be higher than the thermal load on the space for a while to get in energy benefit from the mass storage. Or you can use passive night cooling to cool your mass for later. </div>
<div> </div>
<div>There are many situations where a building would not be able to take advantage of mass, so anecdotes of one particular building model not realizing savings from increased proves that not all buildings will see improvements with increased mass, not that increased mass has zero savings in all cases. My personal experience in modeling mass shows that mass makes a huge difference in the efficacy of passive heating and cooling strategies. I think this paper talks about some of what we found:</div>
<div><a href="http://www.ibpsa.org/proceedings/BS2007/p120_final.pdf">http://www.ibpsa.org/proceedings/BS2007/p120_final.pdf</a><br><br></div>
<div class="gmail_quote">On Wed, Mar 24, 2010 at 10:29 AM, Shaun Martin <span dir="ltr"><<a href="mailto:smartin@shaunmartinconsulting.com" target="_blank">smartin@shaunmartinconsulting.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi Paul,<br><br>My experience on EnergyPlus with this question led me to the conclusion that<br>the time-delayed release or gain of heat in interior concrete walls or<br>
floors is a bit of a fiction. Virtually all of this heat is picked within<br>the first hour by the mechanical systems. Exterior concrete, likewise, had<br>very little impact on the occupant comfort and interior temperatures simply<br>
because of the presence of insulation. However, remove the cooling systems<br>(we do that here in Canada, particularly in residential high-rises) and the<br>picture is very different.<br><br>It would be interesting to repeat the same analysis on a building that is<br>
fully designed to take advantage of passive heating and cooling. Few are, of<br>course. I suspect even partially passive buildings (mixed/hybrid mode) don't<br>experience even a fraction of the purported benefits of thermal mass.<br>
<br>The increase in the heating load is because the assembly is treated as one<br>R-value. Removing the carpet decreases the R and increases the heating load.<br><br>Shaun<br><br>Shaun Martin LEED AP<br>Principal<br><font color="#888888">Shaun Martin Consulting<br>
Suite 200 - 420 West Hastings Street<br>Vancouver, BC V6B 1L1<br>c: 604-789-1095<br><a href="mailto:e%3Asmartin@shaunmartinconsulting.com" target="_blank">e:smartin@shaunmartinconsulting.com</a><br>member CAGBC, ASHRAE<br>
</font>
<div><br><br>-----Original Message-----<br>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a><br></div>
<div>[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Paul Grahovac<br>Sent: Wednesday, March 24, 2010 8:36 AM<br>To: Eurek, John S NWO; Peterson, John (EYP/HP CFS);<br>
<a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br></div>
<div>
<div></div>
<div>Subject: Re: [Bldg-sim] differences between energy simulations programs<br><br>FYI, another comment on TRANE Trace 700: the modeling engineers I hired<br>told me, after consultation with TRANE, that exposed interior concrete<br>
floors, when modeled against the ASHRAE baseline of carpeted floors, showed<br>a reduction in the cooling load, but an increase in the heating load. An<br>increase in the heating load was contrary to my reading in passive solar<br>
books. I used a simplified simulator for lay people, and it showed exposed<br>interior concrete floors improved cold-weather performance over carpeted<br>concrete (HEED, <a href="http://www2.aud.ucla.edu/heed" target="_blank">www2.aud.ucla.edu/heed</a>).<br>
<br>I have since heard that TRANE does not model thermal mass well. I have also<br>not been able to find anyone with experience modeling the thermal mass of<br>interior exposed concrete floors using any simulation tool.<br>
<br>Paul Grahovac, LEED AP<br>PROSOCO, Inc.<br>785-830-7355<br><br>-----Original Message-----<br>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a><br>
[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Eurek, John S<br>NWO<br>Sent: Wednesday, March 17, 2010 3:32 PM<br>To: Peterson, John (EYP/HP CFS); <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>
Subject: Re: [Bldg-sim] Discrepancy between Equest & Trace 6.2<br><br>John,<br><br>It is like buying a car. Do you want a truck, manual/automatic, something<br>fast....... You are asking for information overload. If you know exactly<br>
what you want it may be easier for us (in this list) to help guide you to<br>the best option.<br><br>I also was once curious and found the link below. The end of the paper has<br>charts comparing different features.<br><a href="http://apps1.eere.energy.gov/buildings/tools_directory/pdfs/contrasting_" target="_blank">http://apps1.eere.energy.gov/buildings/tools_directory/pdfs/contrasting_</a><br>
the_c<br>apabilities_of_building_energy_performance_simulation_programs_v1.0.pdf<br><br>Another sight.<br><a href="http://www.wbdg.org/resources/energyanalysis.php" target="_blank">http://www.wbdg.org/resources/energyanalysis.php</a><br>
<br><br>I use Trace 700 (v6.2.4). Why? Because the first, second and third company<br>I worked for used it. It is good for running loads, but so-so for energy<br>modeling. Also I have never used anything else. I have looked at equest<br>
and DOE, they both look like learning a completely new programming language.<br><br><br>I wouldn't mind hearing other people's brief views of the programs they use.<br>Equest, DOE, HAP, ect.<br><br><br><br>John Eurek LEED AP<br>
Mechanical Engineer,<br>US Army Corps of Engineers<br>Omaha District CENWO-ED-DA<br>1616 Capitol Avenue<br>Omaha, NE 68102<br>Phone: (402) 995-2134<br>email: <a href="mailto:john.s.eurek@usace.army.mil" target="_blank">john.s.eurek@usace.army.mil</a><br>
<br><br>-----Original Message-----<br>From: <a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a><br>[mailto:<a href="mailto:bldg-sim-bounces@lists.onebuilding.org" target="_blank">bldg-sim-bounces@lists.onebuilding.org</a>] On Behalf Of Peterson,<br>
John<br>(EYP/HP CFS)<br>Sent: Wednesday, March 17, 2010 2:03 PM<br>To: <a href="mailto:bldg-sim@lists.onebuilding.org" target="_blank">bldg-sim@lists.onebuilding.org</a><br>Subject: [Bldg-sim] Discrepancy between Equest & Trace 6.2<br>
<br><br><br>Has there been any information released on the differences between<br>energy<br>simulation programs? We have a bid requirement with a certain<br>percentage<br>listed and we have been asked to address the differences between the bid<br>
model and the newly proposed model.<br><br><br><br>Thanks in advance -<br><br>John<br><br><br><br>John Peterson, PE, LEED AP<br><br>HP Critical Facilities Services delivered by EYP<br><br>6600 Rockledge Drive, 4th Floor<br>
<br>Bethesda, MD 20817<br><br>cell: 202-731-5835<br><br><br><br>_______________________________________________<br>Bldg-sim mailing list<br><a href="http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org" target="_blank">http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org</a><br>
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