[Equest-users] GSHP Simulation Results

[Chuck Ladd]

Stephen,

I did the energy modeling on a small office building that has 9 GSHPs  
in it. The model showed a substantial savings over the baseline  
(similar to what you report). The baseline building used air-cooled  
rooftop units of standard efficiency. So far, the building is not  
quite as efficient as the model. While less than the baseline, the  
demand kW for the building is much higher than the demand predicted in  
the model. On the other hand, there are some control issues not  
relating to the GSHP units that may be causing the decreased efficiency.

One of the things I noticed about my model is that eQUEST predicted  
that the aux electric heat would almost never run. I am not sure that  
this is the case in reality, and if the changes to the controls do not  
improve the building performance, that is the next thing I will check.

Chuck

Charles Ladd, PE, AIA
Principal Engineer
Williard Ferm Architects, PA
122 Cox Avenue
Raleigh, NC, 27605
W: 919.834.0620 ext. 106
F: 919.834.2149
chuck at williardferm.com

On Apr 24, 2009, at 3:48 PM, Karen Walkerman wrote:

> Are all zones satisfied without too many over or under-heated  
> hours?  eQuest will not auto-size your ground loop for you, and if  
> it's not large enough, your energy use will be really low, but the  
> people in the space will be freezing or roasting, depending on the  
> season.
>
> Have you made the switch in detailed edit mode or in the wizard?  If  
> it's in detailed edit mode, there are all kinds of things that can  
> trip you up a bit.
>
> --
> Karen
>
> On Fri, Apr 24, 2009 at 1:15 PM, Anthony Hardman <Anthony at geoenergyservices.com 
> > wrote:
> Two quick things to check would be the supplemental electric heat  
> (for the air-source system) as well as your loop field design  
> parameters.  Your numbers could be correct if it’s in an extremely  
> cold climate, you’ve oversized the loop field or your loop field  
> ground thermal properties are unrealistic for the area in question.
>
>
> Anthony Hardman
>
> Mechancial Engineer
>
> LEED AP
>
>
> Geo-Energy Services
>
> 14250 E Easter Pl, STE C
>
> Centennial, CO 80112
>
> 303-531-5292 v
>
> 303-805-3563 f
>
> 720-273-9973 c
>
> www.GeoEnergyServices.com
>
>
> From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org 
> ] On Behalf Of Stephen Parker
> Sent: Friday, April 24, 2009 3:03 AM
> To: equest-users
> Subject: [Equest-users] GSHP Simulation Results
>
>
> Hello everyone,
>
> I have modeled a ground source heat pump within the building I have  
> designed and have been getting results that seem almost too good to  
> be true.  I decided to compare my results with a typical high  
> efficiency air side heat pump and discovered that the geothermal  
> system is operating about 65-75% better than the air side heat pump  
> in terms of cost.  The results from the air side heat pump appear to  
> be correct and are reasonable for my design.
>
> Has anybody else ever gotten results for a geothermal system design  
> that were much better than expected?  If so, was there something  
> incorrect within your model or have you deemed it as an internal  
> flaw of eQUEST?  This project is for my masters thesis, so I am  
> trying to justify my results as much as possible.  For my system I  
> am using two 3.5 ton GSHPs with an EER of 21.8 and a COP of 4.4,  
> which is rather efficient.
>
> Thanks,
>
> Stephen Parker
> Bucknell University
>
>
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