Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

Our project is attempting to achieve an innovation credit for reducing process water usage. We have taken CIR ID1.1 Ruling dated 8/31/04 as the basis for the credit, but would like to verify that we have correctly interpreted the prescribed calculation methodology. The project is a residential housing unit on a university campus, that includes a laundry facility as part of the project design. The following is the approach we have taken: We have used the WE Credit 3 letter template to measure the regulated water usage. The regulated building fixtures that were input include toilets, urinals, lavatories, and showers. We then added process water fixtures - washing machines and drinking fountains -to the letter template to measure the process and regulated building loads combined. The baseline case was established as required for WE Credit 3, using Energy Policy Act minimums for base building fixtures. The water use data that was used for the baseline washing machines was taken for a conventional commercial washer from the same manufacturer as the design-case horizontal axis model. For the design case calculations, we used the specified base building fixtures, exactly as used in WE Credit 3, and the specified horizontal washers and conventional drinking fountains. 1) The first method we used was to calculate the savings exactly as described in the previous CIR. In that ruling it is stated that to achieve this credit "The project must demonstrate a process water savings that is equal to or greater than 10% of the regulated water usage as calculated in WEc3". The following are our results: Design regulated water usage = 852,549 gal 10% of design regulated water usage = 85,255 gal Process water savings = 1,072,006 gal Therefore , process water savings are greater than 10% of the regulated water usage. 2) the second method was to calculate the saving of only the process water on the project. The following were our results: Baseline process water = 2,062,798 gal Design process water = 990,792 gal (51.97% savings) Please confirm which of these calculation methodologies meets credit requirements. If neither is correct, please describe the methodology to be used.