[Bldg-sim] Space Cooling Energy Consumption with GSHP

[Adam Young]

Good morning,

 

I am having similar results with a ground-coupled heat pump and am
following this thread closely. I am only realizing savings of about 5%
to 10% over an air-source HP.

 

I believe I am incorrectly separating out the fan-energy on the
air-source units. What is the procedure for getting the fan and
compressor energy separate on the air-source units (12 SEER air-source
unit per 90.1-2004, baseline design)? If I understand correctly, the
GCHP efficiency stated under ARI 13256 does not include external fan
energy or external pump energy, and therefore, the stated GCHP
efficiency can be converted into EIR directly. Correct? 

 

Also, for the GCHP the correct number to use is the "GLHP EER" value
from the manufacturer based on ARI 13256, which is higher than the
water-loop HP (WLHP) ARI EER? Is that correct?

 

Experience tells me a GCHP should realize more savings than what I am
getting, which leads me to believe I am inputting "garbage" into the
model. Thanks for your help!

 

Adam Young

 

________________________________

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Demba
Ndiaye
Sent: Wednesday, May 14, 2008 8:05 AM
To: Tom Butler; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Space Cooling Energy Consumption with GSHP

 

Thomas, 

 

You should definitively have more savings than that, even if there is
the pump energy. 

One first thing to check: the efficiency of GSHP should be much higher
than that of air-source heat pumps in both heating and cooling modes. 

 

______________

Demba Ndiaye

________________________________

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Tom Butler
Sent: Tuesday, May 13, 2008 5:53 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Space Cooling Energy Consumption with GSHP

 

I am modeling an apartment style dormitory for a project in Atlanta, GA.
Each of the 45 units is served by its own heat pump, along with a few
zones for public areas. For an energy efficiency grant application I
have compared the designed system, a ground source heat pump, with an
air source heat pump prescribed by 90.1. Other than the systems, the
models are identical. 

The energy use for space cooling is significantly higher for the GSHP
system (24,000 kWh vs. 17,000 kWh). Because the power required to run
pumps offsets the savings in heating energy, this destroys the rationale
for spending the extra money on the Ground Source Heat Pump, as well as
our chances of receiving the grant.

Has any one encountered this issue? 

 

Thanks 

tb 

Thomas Butler, LEED AP 
Direct Phone 404-253-1435 | Direct Fax 404-253-1335 

LORD, AECK & SARGENT ARCHITECTURE
Responsive Design * Technological Expertise * Exceptional Service 
www.lordaecksargent.com <file:///\\www.lordaecksargent.com>  

 

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