System-level Key Performance Indicators (KPIs) for Building Performance Evaluation

摘要

Quantifying building energy performance is essential for achieving high-efficiency goals for both new and existing buildings. Currently, building energy performance is usually represented either at the whole building level such as site or source energy use intensity (E UI), or at the equipment/ component level such as EER/ SEER for packaged DX equipment, chiller COP, fan efficiency, boiler AFUE or thermal efficiency. Although those metrics provide some insights into how the whole building or individual equipment/ component performs, there lack system-level key performance indicators (KPIs) to represent system-level performance. Building systems are usually complicated and interconnected, identifying KPIs at the system level is critical to have a deep understanding of energy performance and operational efficiencies of building systems. System-level KPIs can be used for performance benchmarking and diagnostics. Moreover, current building energy standards (such as ASHRAE 90.1, ASHRAE 189.1, and California Title 24) do not have a system performance compliance path. A well-defined and validated set of system-level KPIs can be potentially used as a system performance compliance path. This study developed a suite of system-level KPIs and showcased their applications. The KPIs cover major building energy systems, including indoor lighting outdoor lighting cooling heating ventilation, air distribution, water distribution, service hot water, and miscellaneous energy loads. The rationales of KPIs definitions and structures are discussed. To showcase the use of the KPIs, typical KPI values are derived via simulations of the DOE reference large-sized office building models. Future work includes extending the KPIs for other building types, as well as compiling KPIs from measured data of real buildings, which forms a valuable dataset for system performance benchmarking and diagnostics.