Rating System

LEED BD+C: New Construction, LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2, v3 - LEED 2009

Inquiry

In accordance with the Exceptional Calculation Method this CIR seeks confirmation of the approach indicated below in claiming energy savings on process loads. Project Description: This is a water reclamation project that takes water from a wastewater treatment plant and uses micro-filtration/ultra-filtration, reverse osmosis and finally ultraviolet radiation to treat the water. Many large motors drive pumps to move the water through the reclamation facility. The energy used by the pump motors represents greater than 90% of the energy used on the entire campus and represents the best opportunity for energy use reductions. Proposed Approach: The water treatment process runs nearly continuously throughout the year. Periodically, the membranes and filters that the water passes through get clogged, increasing the resistance that the pumps must overcome. Historically designs have used constant speed pumps to drive the water through the system coupled with resistance or bypass flow control devices to maintain constant flow volumes. It is proposed that constant speed motors be used as the basis for the baseline design. The proposed design would utilize variable frequency drives (VFD) to control the speed of the pumps to maintain flow through the system. The VFDs allow for running the pumps at lower speeds which results in lower energy use because percent of total power used at part speed is much less. Under normal conditions, when the membranes are clean, the motors will only need to operate at 80% of full speed. As the membranes begin to clog, the VFDs increase the pump speed to maintain constant flows. Please note that this baseline design and proposed design approach has been recognized and accepted (documentation can be provided) by Southern California Edison (local utility supplying power to the project) through their "Savings By Design" program. This program provides monetary incentive for projects that exceed the energy conservation requirements of California\'s Title 24 and the utility performs their own energy modeling to verify the designed savings. We seek confirmation that our proposed approach to claiming energy savings on the process loads is valid.