[Bldg-sim] Cooling Loads Question

[Diego Ibarra]

Corey, 

You may also want to look at your ground temperatures. DB uses a default 14C as monthly averages for the whole year. Ideally you would use E+ SLAB to calculate ground temperatures for your specific project. On larger buildings and depending on climate, lower ground temperatures normally increase the heating loads. However if one uses E+ recommended approximation Ti - 2C (for larger footprints), on a smaller footprint you do get those kinds of results. Otherwise, if you send me your DB file I may be able to help. 

Best,

Diego

--
Diego Ibarra

MDesS | LEED®AP BD+C
Doctoral Student
Fulbright Scholar
Sustainable Design
Harvard University


On Oct 13, 2010, at 4:35 AM, Diego Ibarra wrote:

Corey, 

You may also want to look at your ground temperatures. DB uses a default 14C as monthly averages for the whole year. Ideally you would use E+ SLAB to calculate ground temperatures for your specific project. On larger buildings and depending on climate, lower ground temperatures normally increase the heating loads. However if one uses E+ recommended approximation Ti - 2C (for larger footprints), on a smaller footprint you do get those kinds of results. Otherwise, if you send me your DB file I may be able to help. 

Best,

Diego

--
Diego Ibarra

MDesS | LEED®AP BD+C
Doctoral Student
Fulbright Scholar
Sustainable Design
Harvard University


On Oct 12, 2010, at 10:34 PM, Cory Estep wrote:

Good Evening Everyone:
I have a question about high cooling loads I am getting in my simulation.  I have developed a simulation in Design Builder, using Energy+ as the simulation engine.  It has been developed acording to ASHRAE 90.1-2007 AppG, and it is for a leased space of 11,000+ SF.  Additionally, I specified System #4 - PSZ-HP.
I double checked my weather file, equipment loads, and lighting loads, and they are within range.  However, my cooling loads are almost 4 times as high as my heating (Heating = 3.4 kbtu/sqft-yr & Cooling = 12.4 kbtu/sqft-yr).
My major concern with this is that when I use CBECS as a reference the heating and cooling loads are almost reversed from what I am getting. 
I have read over the Design Builder Users Manual to verify that I have not overlooked anything, but I am at a loss...
My simulation may be correct, however I did want to get a second opinion.  Any information or suggestions is appreciated.
 
Thanks,
Cory Estep
MARCH/MSSD Candidate
The Catholic University of America
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