Rating System

LEED BD+C: New Construction, LEED BD+C: Core and Shell, LEED BD+C: Schools

Rating System Version

v3 - LEED 2009, v2 - Schools 2007, v2 - LEED 2.2

Inquiry

Ours is a project in India wherein we plan to use high efficiency centrifugal chillers. We have a query on fixing the standard COP which needs to be considered in the baseline. As per the ASHRAE 90.1 2004 standard, for centrifugal chillers of capacities more than 300 TR , the baseline efficiencies are selected as per the table 6.8.1C, when tested under ARI 550/590 conditions. For chillers which operate outside the ARI conditions i.e. non standard conditions, ASHRAE 90.1 2004 refers to a sliding chart as per table 6.8.1J given in page 53. This chart also shows a calculation to arrive at K (adj) factor which has to be multiplied with the COP std (i.e. 6.1) to arrive at COP (adj) as per the site conditions. Accordingly, for our project, we have made a detailed calculation. The building would have centrifugal chillers of capacities 400TR, 600TR and 820TR and the operating site conditions are as follows: Leaving chilled water temperature : 44 deg F Entering condenser water temperature : 90 deg F We have arrived at the K (adj) factor based on the calculations shown in page 53 of ASHRAE 90.1 2004 as follows: BASELINE COP CALCULATION FOR CENTRIFUGAL CHILLERS COPadj = Kadj x COPstd Where, COPstd = 6.10 Kadj = 6.1507 - 0.30244(X) + 0.0062692(X)2 - 0.000045595(X)3 X = Condenser DT + Lift Condenser DT = Leaving Condenser Water Temperature (Deg F) - Entering condenser water temperature (Deg F) Lift = Entering Condenser Water temperature (Deg F) - Leaving Chilled Water Temperature (Deg F) X = Condenser DT + Lift = (100 - 90) + (90 - 44) = (10) + (46) = 56 Kadj = 6.1507 - 0.30244(X) + 0.0062692(X)2 - 0.000045595(X)3 = 6.1507 - 0.30244(56) + 0.0062692(56)2 - 0.000045595(56)3 = 0.86 COPadj = Kadj x COPstd = 0.86 x 6.10 = 5.28 NPLV CALCULATION : NPLVadj = Kadj x NPLVstd Where, NPLVstd = 6.40 NPLVadj = Kadj x NPLVstd = 0.86 x 6.40 = 5.50 We need clarification as to whether a COP of 5.28 at 100% load and NPLV of 5.5 can be considered as the basecase efficiencies while carrying out energy simulation for the building.