[Bldg-sim] FW: eQUEST - City Chilled Water Loop and ASHRAE Appendix G

[Julia Beabout]

Regarding your first question when you're modeling a building connected to a city chilled water loop: 
First - be aware that LEED recently issues new modeling rules for this exact situation.  The document is called "Required Treatment of District Thermal Energy"  and is located at usgbc.org/LEED/LEED Resources/LEED Reference Documents.  If your project was registered BEFORE May 28, 2008, then you can elect to follow these rules.  If you're project was registered AFTER that date, then you MUST follow the new rules.  The rules basically effect the baseline building systems that are modeled....i.e. so what you're comparing yourself to.  
In terms of modeling the situation, (I'm not an Equest user....but, if it's similar to Trace at the plant simulation level) you'd choose "purchased chilled water" as the equipment/system type.  Then you'd input the cost of your chilled water (per therm or other similar unit that your software uses) in the economics portion of the software.
J 



----- Original Message ----
From: Keith Swartz <kswartz at ecw.org>
To: bldg-sim at lists.onebuilding.org
Sent: Thursday, July 17, 2008 4:29:03 PM
Subject: [Bldg-sim] FW: eQUEST - City Chilled Water Loop and ASHRAE Appendix G


Michael,
Regarding modeling “extra” systems for conditioned spaces, the key is “conditioned” spaces. See the definition of “conditioned space” in the standard. If a space has no heating or cooling, it is not a conditioned space. The User’s Manual for ASHRAE 90.1-2004 clarifies that “This requirement only applies to conditioned spaces in the building. Semiheated spaces would only have a heating system; unconditioned spaces would have neither heating nor cooling systems.” (p. G-21) See the definition for “semiheated space” too. I believe the intent here is to add a cooling system to spaces that only have a heating system and add a heating system to spaces that only have a cooling system.
If the model is for LEED, the LEED-NC v2.2 Reference Guide clarifies it. “For areas of the project without heating or cooling systems (such as parking garages), there is no need to model heating or cooling systems in either the Proposed or Baseline Designs.” (p. 181)
I don’t know of any restrictions on the thermostat settings, so you might be able to just make the thermostat setting of the fictitious system pretty extreme so that the system rarely (or never) comes on. This would satisfy the requirement to have a system, but keep your energy consumption numbers more realistic.
Sincerely,

Keith Swartz, PE, LEED® AP
Energy Engineer / Senior Project Manager
EnergyCenterof Wisconsin
455 Science Drive, Suite200
Madison, WI53711

Phone: 608-238-8276 ext. 123, Fax: 608-238-0523
www.ecw.org  The Energy Center of Wisconsin is a nonprofit organization that seeks solutions to energy challenges.

________________________________

From:Michael Bejrowski [mailto:MichaelB at auseea.com] 
Sent: Wednesday, July 16, 2008 2:40 PM
To: Bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] eQUEST - City Chilled Water Loop and ASHRAE Appendix G
 
How do you model a building that is attached to a city chilled water loop?
 
and
 
Have any of you had experience with ASHRAE 90.1 Append. G, Table G3.1, 1c where it says "All conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed,..."?
 
We modeled a building that had heated vehicle maintenance bays, so by the ASHRAE standard it would seem that we could not model it that way, but would have to model it as being heated AND cooled.
 
Any ideas or experience would be greatly appreciated.
 
 
Thanks,
 
Michael Bejrowski
Mechanical EIT
Austin, TX
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