Rating System

LEED BD+C: Core and Shell

Rating System Version

v2 - LEED 2.0

Inquiry

The project is a large mixed use complex which will include a high rise residential tower, a mid rise hotel, a theatre, retail base under each of the above 3 buildings and parking facilities associated with all of the above. We have a question related to satisfying the requirements for condenser heat recovery on the project. A previous CIR from 2/7/07 addressed the requirement of ASHRAE 90.1-2004 Section 6.5.6.2 for condenser heat recovery in buildings with only a portion that is 24 hour operation. The ruling was that compliance with ASHRAE 90.1-2004 Section 6.5.6.2 for condenser heat recovery is dependant on whether the 24 hour operating area has installed chiller capacity and hot water loads above the ASHRAE defined limits. For our project the 24 hour operating area (primarily the residential tower) does exceed the chiller capacity and load thresholds, therefore we understand that the requirements of 6.5.6.2 apply. However, there are several conditions that make using condenser heat recovery for the residential tower impractical. The location of the domestic water storage tanks for the residential tower is over 1000 feet away from the chiller plant, the domestic water system for the residential tower will operate at a much higher pressure than the domestic water system for the rest of the complex and the time of peak service water usage for the residential tower (6-8 AM) coincides very poorly with when the chillers would be operating. Our question is: If site solar or site recovered energy is used to supply 60% of the service water heating for the 24 hour occupied area which exceeds the limits (the high rise residential tower), per exception 6.5.6.2.b can the entire complex be considered exempted from the requirement of 6.5.6.2? Alternatively can compliance with 6.5.6.2 be achieved if the residential tower complies with the 60% target for solar or site recovered energy and the remainder of the complex utilizes condenser heat recovery as required by 6.5.6.2?