[Bldg-sim] Space Cooling Energy Consumption with GSHP

RobertWichert robert at wichert.org
Wed May 14 07:00:33 PDT 2008


Thomas:

The EER and the COP for the GSHP should be substantially higher than the 
air source unit.  Your heat pump manufacturer should have separate ARI 
ratings for air source and GSHP heat pumps.  This is a large source of 
added efficiency.  If your EERs and COPS are not higher with GSHP, you 
are missing out on the advantage entirely.  You should contact your heat 
pump manufacturer for this information.  Both Climate Master and Florida 
Heat Pump have separate ratings for their systems and the GSGHP ratings 
are even higher than the water source heat pump ratings.  Air source 
will be much lower, I believe.  Please check your EERS!

Other areas to increase efficiency modeling accuracy:
VFD on the main circulating pump:  Be sure to use an accurate horsepower 
ratio.
Use the actual HP fan wattages, not the nominal horsepower.  This can 
make a big difference on some units.


Robert Wichert




=============================
Xiaobing Liu wrote:

> Thomas:
>  
> Does the simulated dorm operate 24 hours? What efficiency you 
> specified for GSHP? What is the loop temperature in heating and 
> cooling? Have you checked the pump related input and defaults?
>  
> There are lots of thing can affect the results.
>  
> Xiaobing
>
>     -----Original Message-----
>     *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 4:53 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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