[Equest-users] [EXTERNAL] Re: Why Water Source Heat Pump is not considered as Renewable Energy in LEED rating system? (UNCLASSIFIED)

[Joe Huang]

Frederic,

While I agree with what you wrote about the thermal losses in electricity generation,  I'm 
puzzled by the comment that the overall efficiency of GSHP is worse than that of most 
air-conditioners.  Since both are powered by electricity, an A/C unit is no different in 
terms of  the losses for electricity generation.   Therefore, in comparing the two the 
only thing to consider are their relative COPs.  From what I've heard, GSHPs perform 
better because it's rejecting heat to the ground rather than the air.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 1/7/2015 2:15 PM, Genest, Frederic wrote:
> Mo,
>
> You may also consider the fact that electricity used to power the heat pump generally comes from a thermal plant, coal-powered or otherwise. Efficiency of those plants is generally 33%, or 3:1 energy used to useful energy produced.
>
> Geothermal heat pump with COP of around 3 (which is somewhat optimistic, if we factor in the pumping energy) combined with the thermal plant efficiency brings back the global efficiency to around 1.0, which is not much better than gas-fired condensing boiler (for heating), and worst than most air-conditioner (for cooling).
>
> Hence, not a renewable energy system...
>
> Regards,
>
> F.
>
>
>
> -----Original Message-----
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Aaron Smith
> Sent: Tuesday, December 30, 2014 9:42 PM
> To: YangMo; equest-users at lists.onebuilding.org
> Subject: [EXTERNAL] Re: [Equest-users] Why Water Source Heat Pump is not considered as Renewable Energy in LEED rating system?
>
> Mo,
>
> I've always  assumed it was because they require the use of a compressor so with a COP of 3-4 they're  only 65-75% renewable.  Deep earth geothermal (that doesn't use a heat pump) ‎is considered renewable.  
>
> Looking at the reference guide, they state that ground-source heat pumps use vapor compression systems for heat transfer and they do not obtain significant quantities of deep earth heat.  
>
> Aaron Smith, P.Eng
> M&R Engineering Ltd.
>
> Sent from my BlackBerry 10 smartphone on the TELUS network.
>    Original Message  
> From: YangMo
> Sent: Monday, December 29, 2014 23:14
> To: equest-users at lists.onebuilding.org
> Subject: [Equest-users] Why Water Source Heat Pump is not considered as Renewable Energy in LEED rating system?
>
> Hi all,
>
> This question is not about eQUEST, but since in this group a lot of people are working for LEED consultant projects, I think it is a good place to ask this question. I have been working in U.S. for a lot of years and just came back to China recently. In China ground source heat pump and water source heat pump systems are very very popular, and they are considered as renewable energy, since they use free heat from the soil and water. But in LEED rating system, heat pump is not considered as renewable energy. Why? Is it because those system has side effect to the environment?
>
> Thanks!
> Mo Yang
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