Rating System

LEED O+M: Existing Buildings, LEED O+M: Existing Buildings, LEED O+M: Existing Buildings

Rating System Version

v2 - LEED 2.0, v3 - LEED 2008, v3 - LEED 2009

Inquiry

Our project is an office building in downtown Toronto, Ontario. The building owners made the decision to connect to a community chilled water loop sourced from a nearby deep lake which provides naturally cooled water. This essentially eliminates the need (both on-site and at source) for a chiller and any related energy demands which would be needed. We have confirmed with Energy Star that "Portfolio Manager does not have a specific method of accepting cooling energy supplied by a non-chiller driven chilled water loop." Currently, we are required to input our deep lake cooling energy into Energy Star as district cooling which gives us the option of electric or gas fired, absorption chillers at the central cooling plant. Both of these options assume coefficients of performance much below that of our plant and as a result out project is being penalized. Following from our discussions, we understand that Energy Star will be considering future revisions of their tool to better address deep lake cooling, but no option exists now. Energy Star\'s states that "An individual building does not receive either a bonus or a penalty based on the efficiency of its utility provider" because "individual buildings do not have control over the available power supply options in their geographic area" [ENERGY STAR Performance Ratings: Methodology for Incorporating Source Energy Use]. We understand this in the context of a single energy source such as electricity. However, where building owners do have control, such as a choosing between natural gas heating and electric heating, buildings are rewarded under Energy Star for selecting the lower impact energy source, natural gas, (assuming a reasonable conversion efficiency) because of its lower source-site energy ratio. In the case of deep lake cooling, building owners are decisively choosing their source of cooling to reduce environmental impacts (and not for economic consideration as lake-cooled community water loop cooling is typically more costly per ton-hr than cooling from a conventional chiller). Since the cooling energy being delivered is produced without electric chillers, we propose that we input into energy star the actual electricity used in pumping the chilled water to our site instead of the tons of chilled water received. This will be done by using the utility\'s stated efficiency (in kW/ton) and the building\'s consumption, via the equation: Electricity cooling [kWh] = Efficiency utility [kW/ton] x Consumption Building [ton-hrs] Please confirm that, since deep lake cooling is not mechanically derived, when calculating an EPA Energy Star rating for the building the cooling energy provided to a building by this means can be accounted for by inputting the electricity used by the utility to generate and distribute the cooling consumed.