[BLDG-SIM] LEED ECB Question - System 6 Components

[Pat Dolan]

I am looking for some guidance from ASHRAE 90.1 modelers.  I have a couple
of projects in Chicago where the proposed system is comprised of ground
loop-coupled water-to-air heat pumps.  My question is regarding compliance
with ASHRAE 90.1-1999 ECB method (the projects are to be LEED v2.1
certified).  I am using eQuest v3.55.  Given that we are using the ground
loop and this is a non-residential multi-zone project, I have to use the ECB
Budget System 6 (constant volume Water-source heat pumps with DX cooling and
boiler heating) as the Budget System.  That seems straight forward, except
that I am not sure how to handle heat rejection from the condenser/DX coil
on the heat pumps for a small building given the limited guidance in
90.1-1999.  
 
In most cases I would use a cooling tower for heat rejection from the
condenser loop as the Budget System.  Has anyone had successfully proposed
using a cooling tower/fluid cooler for  the ECB Budget System 6 for a
relatively small system (less than 12 tons of cooling load) with the USGBC?
It seems like overkill to me to use cooling tower with an additional pump
and head loss, and the percent of energy saved over the GLHP system reflects
that.  I know that Appendix G's Budget System in my case would be a packaged
HP with an air-cooled condenser for rejection.  But I want to find out if
there is any precedent for the heat rejection for 90.1-1999's Budget System
6.  Any help you could give me would be great.
 
Patrick Dolan
Serena Sturm Architects, Ltd.
3351 Commercial Ave.
Northbrook, IL  60062
847-564-0370, ext. 24 voice
847-205-5089, fax
 
 


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