Utah Engineers Journal 2021 Issue

40 Gabriel Legorburu, P.E., Ph.D. Gabriel Legorburu specializes in energy modeling, optimization and mechanical design for Industrial facilities and campuses. He is enthusiastic about designing robust, cost-effective, and efficient mechanical systems that meet client expectations. He is currently a senior mechanical engineer and mechanical team leader at Food Tech, a nationally recognized design builder that constructs food and beverage companies’ facilities. Gabriel has worked in the construction industry for 17 years and currently holds licenses in states across the U.S. He received his Ph.D. in Mechanical Engineering from the University of Utah, a master’s in Mechanical Engineering from Ohio University, and a bachelor’s degree from the University of Nevada, Reno. In contrast, the medium office is best served by an air-source VRF system, as shown in Figure 2. The VRF system allows for load sharing between different spaces and is more efficient with a smaller EUI than the packaged DX rooftop unit with a gas furnace. Given that the medium office has a much lighter heating and cooling load than the large office, the VRF system doesn’t cause significant electrical demand charges, reducing the annual operating cost compared to the VRF system serving the large offices. When viewed as a wholistic campus, the base case scenario has the worst EUI and operating costs, followed by the electrification scenario and, finally, the hybrid scenario. (Figure 3) By far, the best performing system type for the campus is a central plant because the waste heat from the data centers can be recovered and reused throughout the campus. Furthermore, the water-to-air heat pumps have a higher efficiency than air-source VRF because the condenser loop is maintained at a moderate temperature year-round. References • DoE, U. S. (2011). Buildings energy data book. Energy Efficiency and Renewable Energy Department, 286. • Energy Information Administration (U.S.) (Ed.). (2012). Annual Energy Outlook 2012: With Projections to 2035. Government Printing Office. • Commercial Prototype Building Models. (n.d.). Retrieved January 31, 2021, from https://www.energycodes.gov/development/commercial/ prototype_models • CBECS (2015). Commercial buildings energy consumption survey (CBECS). U.S. Department of Energy: Washington, D.C., USA. Figure 3. Campus Level Energy Use Intensity and Energy Costs Figure 2. Medium Office Energy Use Intensity and Energy Costs This article describes a high-level energy modeling technique for evaluating campus buildings during the early design phase. Utilizing the PNNL template files makes it possible to quickly evaluate different HVAC systems for multiple buildings in an office campus. This approach can be beneficial during the design phase because it makes it possible to simulate different building types without creating full building energy models from scratch. Additionally, it is possible to simulate multiple buildings from a campus-level perspective to see if there are opportunities to reduce energy consumption and cost by interconnecting buildings with complimentary load profiles. It is important to note that this high-level approach is best suited for eliminating design choices early on. If different scenarios have relatively similar EUIs or operating costs, then detailed energy modeling should be conducted once the project is more fully defined. Continued from the previous page