Forum discussion
NC-2009 EAc2: On-Site Renewable Energy
I am working on a European project where groundwater is directly used for space cooling without any vapor compression cycle. The system is approved by he local authorities.
Does anybody know if such a system is eligible for on-site renewables?
Thanks, Jens
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Can I pursue this credit if I am using one of the prescriptive compliance paths for EAp2/EAc1?
Can I really double-count onsite renewable energy in both EAc2 and EAc1?
Our PV system is being installed after the building is occupied. Is that okay?
Shillpa Singh
Senior Sustainability ManagerYR&G
131 thumbs up
June 3, 2010 - 4:54 pm
Jens, this sounds like 'geothermal' system as you are using the groundwater directly and not through a heat pump. If so, then yes this system can potentially be a renewable energy source.
Victoria Lockhart
Arup Associates125 thumbs up
June 4, 2010 - 11:08 am
does anyone have practical experience of this working in review? In the "Required Treatment of District Thermal Energy in LEED-NC version 2.2 and LEED for Schools Version 1.0 May 28, 2008" https://www.usgbc.org/ShowFile.aspx?DocumentID=4176 (page 9) it states the following:
Renewable energy sources as defined in LEED-NC v2.2, EAc2 (e.g., electricity, heat, or chilled water energy produced from photovoltaics, solar thermal systems, wind turbines, geothermal, low-impact hydro, wave/tidal, untreated wood waste, agricultural crops or waste, animal and other organic waste, and landfill gas) are the only renewable sources allowed for credit under EAc2. The use of air; ocean,
lake, or river water; or ambient earth for a thermal heating or cooling sink is categorized as an efficiency strategy in LEED and falls under EAc1.
This Reference, although orginally written for 2.2, is still valid until the USGBC update it (appear in the Registered Project Tools for NC 2009).
Thanks!
Tristan Roberts
RepresentativeVermont House of Representatives
LEEDuser Expert
11477 thumbs up
June 4, 2010 - 11:50 am
I agree with Victoria, that this is unlikely to work. The Reference Guide specifically allows for geothermal heating, but this is more like geothermal cooling, which is kind of an oxymoron.Seems more like an efficiency strategy, like using an economizer.
Scott Bowman
LEED FellowIntegrated Design + Energy Advisors, LLC
LEEDuser Expert
519 thumbs up
June 4, 2010 - 5:03 pm
While researching the topic of renewables from a central plant, I noticed that the District Thermal Energy document states the following:
"Renewable energy sources as defined in LEED-NC v2.2, EAc2 (e.g., electricity, heat, or chilled water energy produced from photovoltaics, solar thermal systems, wind turbines, geothermal, low-impact hydro, wave/tidal, untreated wood waste, agricultural crops or waste, animal and other organic waste, and landfill gas) are the only renewable sources allowed for credit under EAc2. The use of air; ocean, lake, or river water; or ambient earth for a thermal heating or cooling sink is categorized as an efficiency strategy in LEED and falls under EAc1."
It would appear from this that the use of "ocean, lake or river water" covers ground water as well. So I would not think this could be considered a renewable, but obviously would help you in your energy performance. Also, LEED does not accept using ground water as a replacement for potable water in WE credits, so it would seem inconsistent to view it as renewable for energy.
Maria Porter
Sustainability specialistSkanska Sweden
271 thumbs up
April 29, 2011 - 9:32 am
I am working on a similar project and am wondering Jens, if you have gotten any further with EAc2? In my project the cooling need will be completely met by this system and it will save a large amount of energy used for cooling. It is a form of geothermal cooling but only geothermal heating is allowed according to the Reference Guide. Have you tried a CIR? Any other tips anyone?
Tristan Roberts
RepresentativeVermont House of Representatives
LEEDuser Expert
11477 thumbs up
May 26, 2011 - 7:41 am
Maria, I don't think this is allowed. In true "geothermal," the Earth is being used as an energy source. In cooling systems like this, the earth or water source is used to improve efficiency for the heat pump—it's not truly a source of energy. Because it's about efficiency, it is already covered under EAp2/EAc1. Make sense?
Jens Apel
134 thumbs up
November 3, 2011 - 5:28 am
It may be too late for current questions but useful as future reference. We put in a CIR and "geothermal cooling" is not eligible. See description, question and ruling below:
Groundwater use:
According to the BD+C Reference Guide, geo-exchange systems are not eligible if they make use of a heat pump or another vapor compression system. Geothermal heating systems which use heat directly are eligible. It is our understanding that the direct use of #cool# from groundwater to cool inside the project building falls under this same principle: building energy costs are offset and #thermal energy for primary use at the building# is provided.
The proposed system uses groundwater directly to provide high temperature radiant cooling with chilled ceilings. There will be no vapor compression cycle between groundwater wells and chilled ceilings. The whole system is approved by the local authority having jurisdiction. Detailed analyses have been conducted by geology consultants to show that there are no negative impacts on the groundwater stream due to heat introduction. Groundwater contamination will be prevented through hydraulic separation with a heat exchanger.
Question:
Is the use of groundwater as described above eligible as renewable energy under EAc2?
Issue # 1: Directly-used groundwater as a renewable energy source
The direct use of ground water for cooling is not considered a renewable energy source. In this application, the ground water just acts a thermal fluid and uses the thermal mass of the earth to reject heat. It is therefore a geo-exchange system. The project will achieve credit under EA Credit 1 for this system because the pumping energy will be the only purchased energy required. However, this does not qualify as a renewable energy source under EA Credit 2.