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?
The applicant is requesting clarification regarding prescriptive condenser heat recovery requirements for a mixed use project that includes both 24 hour and non-24 hour functions. The applicant provides two possible paths of compliance with the prescriptive condenser heat recovery requirements in ASHRAE 90.1-2004 Section 6.5.6.2: Option A: the exemptions from the condenser heat recovery requirements described in ASHRAE 90.1-2004 apply only to the loads for the 24-hour portion of the facility, or Option B: the 24-hour portion of the facility meets the exception of 6.5.6.2b (where 60% of the service hot water load for this portion of the facility is provided by solar or site recovered sources), while the remainder of the facility complies with the condenser heat recovery requirement in 6.5.6.2. It is acceptable to prescriptively comply with the condenser heat recovery requirement using Option B above. Please note that this ruling does not alter the methodology for documenting energy performance improvement in EAc1, where condenser heat recovery must be modeled for the entire facility in the Baseline building design regardless of the exceptions to 6.5.6.2 (Table G3.1(11)(Baseline)(f)). Applicable Internationally.