Monday, January 30, 2017: 8:00 AM-9:30 AM
Building Operation and Performance
Chair:
Michael Deru, Ph.D., NREL
Technical Committee: 2.8 Building Environmental Impacts and Sustainability
CoSponsor: 7.6 Building Energy Performance
Measuring progress toward achieving net zero energy buildings can be difficult. Performance metrics such as energy use index and energy rating index will provide misleading information if they are insensitive to the impact of parameters such as size, process loads, and occupant behavior. This seminar highlights challenges facing popular performance metrics targeted toward net zero buildings. Options for addressing some of these challenges will be described, including lessons learned from an extensive evaluation of airport terminals, and technical approaches such as O&M Index and Index Adjustment Factors to address disparities in ratings caused by geometry and operating assumptions.
1 An O&M Index Can Help Address EUI Limitations
Energy performance indices are used around the world to evaluate and monitor residential and commercial building energy performance during design, construction, renovation, and operation. Building energy performance is sensitive to the engineered system, O&M practices, and occupant needs, each of which are largely independent factors requiring more than one index to describe and manage the building’s energy performance. This presentation analyzes the merits and weaknesses of common indices and introduces the O&M Index, which is the ratio of the energy consumption at the meter to the simulated energy performance, calibrated for the actual operating conditions of the building.
2 Developing EUI Adjustment Factors for Benchmarking Airport Terminal Buildings
A recent study of Airport Terminal Buildings by the Airport Cooperative Research Program revealed that traditional Energy Use Indices (EUIs) do not fully explain the differences in the energy use characteristics of Airport Terminal Buildings (ATBs). To resolve this issue new indices were developed and demonstrated that more accurately account for the special systems in ATBs. This presentation presents the findings of this effort, including the new Energy Use (EU) indicators and preliminary results of the application of the ATB EUs to selected airports in the U.S.
3 ERI Adjustments for Standard 90.2 and Other Residential Applications
Experience with the Energy Rating Index (ERI) score as a building energy performance metric indicates that home geometry and operating assumptions play a significant role in resulting scores. All other things equal, as home size increases it becomes easier to achieve lower scores. The number of bedrooms and number of stories also impact scores. This presentation highlights the magnitude of the disparities caused by each of these factors in high performance zero energy ready homes. It also provides details on a set of Index Adjustment Factors that account for these impacts and significantly reduce disparities in the revised ERI calculation.