The maximum number of points for Water Efficiency Credit, Cooling Tower Water Use can be obtained by

The maximum number of points for Water Efficiency Credit, Cooling Tower Water Use can be obtained by
A . utilizing a once-through system without recirculation
B . limiting cooling tower make-up to 50% of a potable source
C . conducting a one-time potable water analysis to determine acceptable non-potable sources
D . achieving a minimum of 10 cooling tower cycles by increasing the level of make-up water treatment

Answer: D

Explanation:

Achieving a minimum of 10 cooling tower cycles by increasing the level of make-up water treatment is the way to obtain the maximum number of points for Water Efficiency Credit, Cooling Tower Water Use. This credit aims to conserve water used for cooling tower equipment by encouraging the use of non-potable water sources and increasing the cycles of concentration1. The cycles of concentration are the ratio of the concentration of dissolved solids in the blowdown water to the concentration of dissolved solids in the make-up water2. Increasing the cycles of concentration reduces the amount of make-up water and blowdown water, and thus saves water and energy2. The credit has two options: Option 1. Non-potable Water Source (1 point) and Option 2. Cooling Tower Water Use (2 points). Option 1 requires using at least 50% non-potable water for cooling tower make-up water1. Option 2 requires achieving a minimum number of cooling tower cycles based on the quality of the make-up water, as specified in Table 1 of the credit requirements1. The maximum number of cycles is 10, which can be achieved by increasing the level of make-up water treatment to meet the criteria for conductivity, silica, and alkalinity1. Therefore, Option 2 is the way to obtain the maximum number of points for this credit.

Reference: Credit: Cooling tower water use | U.S. Green Building Council Cooling Tower Evaporation Credits | WaterSignal