Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.2

Inquiry

We request further clarification regarding the use and appropriateness of ASHRAE 90.1 in order to establish a baseline energy model for E&A Prerequisite 2 and Energy Credits 1.1-1.4. We are currently designing a science and classroom university building of approximately 170,000 sf. Approximately 25% of the building is office space, 50% laboratory space and 25% general classroom space. Despite utilization of our best possible design to otherwise minimize outside air to the building with reduction in total HVAC energy and maximization of diversity, the resulting integral building systems cannot satisfy ASHRAE 90.1 requirements due to high makeup air requirement to satisfy laboratory needs. ASHRAE 90.1 Section 6 requires no more than 1.5 nameplate horsepower (includes supply air, return air and exhaust air fans)/1,000 cfm of supply air. Laboratories are typically 2 to 4 times that amount due to specialized equipment (hoods, filters, etc.) and large air flow. We understand that the USGBC previously clarified that "Specialized loads found in laboratory spaces are a form of commercial energy use, or process energy. For the purpose of LEED, the energy required to operate special ventilation equipment such as fume hoods and HEPA filters, as well as load associated with 100% outside air, should be considered "non-regulated" energy components. This energy use shall be excluded from the numerator and denominator of Equation 1 as described in the June 2001 version of the LEED reference Guide (p.128)" We also understand that there is currently a consensus-based group working to develop a laboratory rating system called Labs 21 Environmental Performance Criteria (EPC). The EPC directly addresses the use of ASHRAE 90.1, and has provided modifications to make the guideline more appropriate to laboratories, as well as providing incentive to reduce the energy loads that the USGBC has defined as "non-regulated." Having carefully reviewed ASHRAE 90.1, the reference manual, prior LEED credit guidance, and the developing Labs 21 EPC, we suggest the following methodology: 1. Establish an energy base line for the mixed-use building, as defined by the EPC guidelines. Use the Energy Cost Budget Method, with the following modifications to ASHRAE 90.1: A. FUMEHOOD / EXHAUST DEVICE DENSITY Base Case: Same as proposed design Proposed Design: As designed with best practices B. PLUG LOADS Base Case: Same as proposed design Proposed Design: As designed based on operation C. LIGHTING POWER DENSITY Base Case: 2.0 W/sf (net) Proposed Design: As designed D. FUMEHOOD CONFIGURATION Base Case: 100 fpm face velocity w/ vertical rising sash 18" open Proposed Design: As designed E. VENTILATION SYSTEM CONTROL Base Case: 100% outside air, constant volume Proposed Design: As designed, using same occupied hours schedule as budget design 2. Incorporate sustainable strategies into the proposed design, resulting in energy savings. A large portion of these efforts will be focused on the reduction of energy use in the areas that previous LEED interpretations have deemed "non-regulated." 3. Show the percent energy savings using ASHRAE\'\'s Energy Cost Budget Method and the Exceptional Calculations Method, incorporating the above modifications. Please advise.