I am modeling a high rise 48 story building consisting of retail spaces for the first 6 levels and office spaces on top. The retail spaces are cooled by 3 chillers and 3 cooling towers located on the 6th level.
The office spaces are cooled separately by 5 water cooled chillers with primary-secondary distribution configuration. These chillers are located on the 7th level which houses other mechanical equipment while the 5 cooling towers are located on the roof deck of 48th floor. Chilled water distribution is constant primary-variable secondary configuration. The office floor levels (4m floor to floor height) are divided into low zone, mid zone, and high zone with each zone served by secondary chilled water pumps sized accordingly to meet the head required. The project is registered for LEED certification.
My question is regarding the Appendix G pump input power of 22 W/gpm and 19 W/gpm for the chilled water pumps and condenser water pumps, respectively. The designed capacities of the pumps for the office cooling system are double these limits and therefore negatively affecting the energy performance of the project. Has anyone encountered this situation? Is there any allowed adjustment to the Appendix G limits to account for the high head of the cooling system? Any suggestion is highly appreciated. Thank you in advance.
