We are in schematic design on a CS project. The project will have underground parking and will use piles as a foundation. Because they are digging so deep we looked in to using geothermal piles and found that they would pay back in around 9 months, Fantastic! Except… we also found that they are not eligible for the renewable energy credit.
Here are some bits of information I have found:
LEED allows you to take credit for technologies that generate electricity and heat from sun, wind, water flows, and waste biomass. It also allows certain thermal technologies, such as solar hot water, concentrating solar collectors, biomass, and geothermal (extraction of heat from within the Earth, not ground-source heat pumps).
You can double-dip with onsite renewable energy. In addition to earning this credit, renewable energy helps to offset total annual building energy use, contributing to EAp2 and EAc1, if using Option 1: Whole Building Energy Simulation.
I am still looking for a deeper explanation for my client on why one type of geothermal is in while the other is not even though both are reducing the building consumption through energy inherent in the natural world.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5915 thumbs up
October 5, 2012 - 5:58 pm
Technically they are not both geothermal even though ground source heat pumps are often incorrectly referred to as geothermal.
Ground source heat pumps rely on vapor compression cycles which run on conventional electricity. So this is more of a hybrid system with only a portion of "heat" provided by the Earth.
True geothermal (in areas with hot springs and geysers and volcanos) is typically at pressures and temperatures which allow it to be used without requiring any or very minimal electricity.
Katie Mesia
Regional Director of SustainabilityGensler
3 thumbs up
October 10, 2012 - 8:39 am
I recived this response from USGBC:
Thank you for the inquiry, asking about geothermal heat pump systems. It's a common question, and we are glad to address it.
Geothermal heat pump systems are eligible for use within the Energy Model for EAp2/c1, but are not eligible as "renewable energy systems" for EAc2. This type of geothermal energy takes advantage of site conditions for increased energy efficiency in much the same way that seasonal temperature ranges allow buildings located in moderate climates to employ economizers and take advantage of unconditioned supply air. These systems reduce the need for mechanical space conditioning but do not represent a renewable energy generation source. The reference to 'geothermal systems' in the Design Approach section of EA Credit 2 concerns the use of high temperature geothermal energy for the generation of electricity.
The basis of EAc2 is on-site renewable energy generation. Site conditions that allow for economizer use or geothermal heat pump systems reduce grid draw, but do not generate energy, and are not eligible as renewable energy systems. The intent of EAc2 is to encourage and recognize increasing levels of on-site renewable energy self-supply to reduce environmental and economic impacts associated with fossil fuel energy use. More detailed information about the eligible and in-eligible systems for EAc2 is available under the implementation section for EAc2, on page 291 in the LEED 2009 BD+C Reference Guide.
The contributions of these systems toward energy-efficiency are reflected in project-wide energy efficiency levels and facilitate the achievement of EA Prerequisite 2 and EA Credit 1.
You may also want to refer to LEED Interpretation # 5976 (https://www.usgbc.org/Login.aspx?REFERRER=/leedinterpretations/lilanding...) which states that:
"The LEED Reference Guide v2.1 states that in order to qualify as renewable energy under EAc2, geothermal energy (hot water / steam) must be used to generate electricity. As the described application does not generate electricity, it does not qualify as a renewable energy source under the requirements of this credit. The energy savings associated with the proposed strategy may, however, be incorporated in the calculations for EAc1, Optimize Energy Performance." LI 5060 provides similar guidance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5915 thumbs up
October 10, 2012 - 10:05 am
The Interpretation is a bit dated in one respect. Geothermal used directly as a heat source would also qualify under EAc2.