Page 96 - Zero Net Energy Case Study Buildings-Volume 1

CASE STUDIES NO. 5 AND 6
UNIVERSITY OF CALIFORNIA, MERCED
Energy Demand: Setting Design Energy Budgets at UC Merced
The approach to establishing energy budgets for buildings at UC Merced is the Benchmarking method discussed in the Introduction. In 2002, Karl Brown of the California Institute for Energy Efficiency (CIEE) and the University of California Office of the President, proposed a benchmark- ing method for the design of all new buildings for the University of California based on actual data for energy use and peak electric load at current UC campuses2. This method was specifi- cally developed in anticipation of the design and construction of an entirely new UC campus at Merced, “built from scratch”, where there was a mandated initiative for an advanced design for a carbon neutral, energy-efficient campus.
A key concept to this benchmarking approach is to use real data for comparable buildings under typical use patterns rather than create performance targets based on comparisons to hypotheti- cal designs, which is the approach of energy codes and standards. This was seen as more likely to lead to achieving the goal of actual zero net energy performance for all campus buildings by 2020.
The benchmarks, created primarily through a rigorous statistical analysis of data from the exist- ing post-1999 buildings on other UC and California State University (CSU) campuses, provide “baseline” numbers for three broad categories of buildings: (1) laboratory buildings; (2) class- room, office and library buildings; (3) housing, student services and recreational. The energy budgets for new buildings are set based on a fixed percentage of these benchmark numbers3. The idea is that the University will verify the feasibility of meeting these energy budgets and then ratchet down the percentage in subsequent phases based on the measured results of the early phase buildings.
The facing page shows a chart of these benchmark targets for the building EUI, the common measurement of annual energy use in buildings. The table lists the current energy design bud- gets based on 50%-of-benchmark targets for the significant categories of energy use and energy demand.
For Phase 1 buildings, two of which are case studies in this publication, the percentage was set at 80%-of-benchmarks. As an example, the Phase 1 laboratory building annual total energy budget was set at an EUI = 263 kBtu/sf-year and the Phase 1 classroom/office building annual total energy budget was set at an EUI = 57 kBtu/sf-year. Because these buildings are currently performing much better than targeted, close to 50%-of-benchmark levels according to ongoing measurements and data collection, the current Phase 2 building energy budgets are set at this 50% mark4.
In addition, the campus set similar “stretch” standards on a building per-square-foot basis for the peak power demand, peak natural gas use and the peak tons of chilled water from the campus central plant relative to the benchmarks. By using disaggregated energy commodities the cam- pus was better able to evaluate development of building design features, a capability that is lost if only EUI is considered5. However, for comparison to other buildings in general, the EUI is the usual reference number considered for energy budget targeting for ZNE buildings of different types.
Metered performance measurements indicate that the budgets can be lowered to 40%-of-bench- mark and this will be investigated in the next phases of design and construction. There is an ultimate goal of 25%-of-benchmark for future phases, known as “Striving to 25”, which would
2 K. Brown, “Setting Enhanced Performance Targets for a New University Campus: Bench- marks vs. Energy Standards as a Reference?”, Proceedings of the 2002 ACEEE Summer Study of Energy Efficiency in Buildings. 4:29-40. Washington D.C.: American Council for an Energy-Efficient Economy, May 2002.
3 The benchmark numbers are based on site energy accounting and include all plug loads. (See Glossary of Terms for definitions.)
4 UC Merced Design Standards, Version 3, December 2010, Energy, Ch. 5: Mechanical, Elec- trical, Plumbing and Facilities Support, Table 5.1.
5 Private communication with John Elliott, Former Director of Sustainability, UC Merced (3/2014).
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Zero Net Energy Case Study Buildings: Volume 1