Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

Intent: To properly calculate the energy points available in EA credit 1 Option 1 for connection to an innovative district cooling system in lieu of constructing an independent building cooling plant system. Background: The project designed and connected to an innovative district cooling system in lieu of building an independent cooling plant system for the new office. District Cooling has also proven to be a major contributor to Greenhouse Gas reduction in many cases. It displaces peak electric power demand with district cooling and storage using ice or chilled water. This benefits the local power grid by reducing peak power demand and alleviating power congestion due to power transmission limitations in cities. So district cooling not only helps cool cities, it helps alleviate the challenges posed by high electric consumption. It is considered that the project may account for the environmental benefit of connection to an efficient central system through points in EAc1 because of significant energy cost saving. While the highly prescriptive modeling outlined in ASHRAE 90.1 and the LEED template does not clearly identify methodology for proposed modeling that would be appropriate to recognize the environmental benefits of tying into this central system rather than utilizing building-specific refrigerant systems. Proposal: We propose to follow the methods specified in credit EAc1 with the following clarification: For modeling cooling energy use, two steps are proposed for the energy model implementation. Step 1 (Building stand-alone scenario): Perform an initial model run on the project building to determine the number of EAc1 point earned without the effect of the district cooling system, i.e. by modeling only purchased chilled water for both baseline and proposed model with actual energy source cost. The achievable points will be depended on the cost saving according to EAc1 requirement. Step 2 (Aggregate building/District Energy Source scenario): Perform a second model run that incorporates the effects of the district cooling system. For the baseline model rats are applied to the code-compliant cooling plant as instructed in Appendix G. Chiller efficiency with energy losses will be used in the proposed model. The achievable points will be depended on the cost saving according to EAc1 requirement. The total number of EAc1 points achievable will be points gained in Step 1 and a maximum 4 points in Step 2. Please confirm that this is an appropriate method for modeling the proposed model condition and comparing energy impacts.