This Credit Interpretation Request is in reference to a 92,000 square foot office building and research laboratory that includes a 5000 square foot data center. To obtain credits for Optimized Energy Performance, we plan to estimate the energy consumed using Option 1-Whole Building Energy Simulation as outlined in ASHRAE 90.1, Appendix G. The LEED modeling protocol sets the process load as 25% of the total building energy load. Credit Interpretation for Energy and Atmosphere EAc11 dated 11/3/2006, ruling #5 \'addresses setting the process load at 25% of total energy by default, unless it is a process dominated building\'. The portion of non-regulated energy consumed by the data center equipment and the research laboratory will exceed 50% of the total building load and will dominate the total building energy use. The large non-regulated process load of the data center and research lab will unfairly minimize the percentage of total energy savings applied to the regulated loads. In order to fairly evaluate energy savings of the enhanced building and systems, as well as utilizing photovoltaic arrays, we plan to exclude the energy consumed by the equipment associated with the data center and research laboratory from the energy simulation calculations. It is noted that with the process equipment in the labs and the data center equipment loads, this percentage of energy derived from the PV array will be very small. Is this the proper approach, or should we use the default process load of 25% of the total building load, or the actual loads for these systems?
The project is requesting clarification regarding modeling procedure for buildings where process energy constitutes a large portion of the total building loads. According to Appendix G, Table G3.1.1, "all end-use load components within and associated with the building shall be modeled." The "default" process energy of 25% defines the minimum percentage of process energy that should be modeled for a typical building. However, buildings that exceed this percentage should model the process energy as designed in accordance with the Appendix G requirements. For buildings that are lower than this percentage, the LEED submittal must include supporting documentation substantiating that process energy inputs are appropriate. This process energy may not be removed from the model during post-processing, and must be included when calculating the Baseline Performance, Proposed Performance, and Percentage Improvement. For buildings where process energy constitutes a large portion of the total load, the Baseline HVAC assumptions listed in Appendix G allow for substantial energy improvements for a well-designed HVAC system. According to Exception to G3.1.1, System 3 or 4 (a packaged single zone system) shall be modeled for any space that has occupancy or process loads that vary significantly from the rest of the building, including peak thermal loads that differ by at least 10 Btu/h-ft^2. Therefore, for a building with a large data center, the HVAC energy savings potential relative to the Baseline design is far greater than for a similar office building without a large data center. As a result, the percentage energy savings for a good design may be comparable between the two cases even though the process energy costs as a percentage of total energy are significantly different. Applicable Internationally.