Research Article Building Thermal, Lighting, and Acoustics Modeling E-mail: jsrebric@umd.edu Impacts of building operational schedules and occupants on the lighting energy consumption patterns of an office space Payam Delgoshaei 1 , Mohammad Heidarinejad 2 , Ke Xu 1 , Joshua R. Wentz 1 , Parhum Delgoshaei 1 , Jelena Srebric 2 () 1. Department of Architectural Engineering, The Pennsylvania State University, University Park, PA 16802, USA 2. Department of Mechanical Engineering, The University of Maryland, College Park, MD 20742, USA Abstract This paper considers pre-retrofit and post-retrofit lighting energy end-use of two sub-metered office spaces. Building lighting retrofits are typically installed to reduce energy consumption and operational costs of buildings. This traditionally includes replacing lights and introducing Building Management System (BMS). Through this process, an occupant’s ability to override new computerized controls could be compromised, which can dramatically affect the overall success of the project. Therefore, the analysis focuses on the effectiveness of the lighting retrofit, influence of the BMS upgrade, occupant behavior, and the lessons learned. The analysis comprises three different phases including one pre-retrofit and two post-retrofit phases. Each of the retrofit phases lasted approximately one year, leading to the monitoring of three years of sub-metered lighting energy end-use. The results showed that when the occupants had access to the lighting switches while BMS managed the operational lighting schedule, the office area with the responsible occupant saved 23.2% compared to the pre-retrofit phase. For the second lighting retrofit phase when the occupants did not have access to the light switches, the lighting schedule operated for more than two hours after the typical work day and the occupant was not able to turn off the lights upon departure. It should be noted that there are limited numbers of studies that consider three years sub-metered lighting retrofit data with the presented granularities in this study. Similar lighting retrofit projects could benefit from the findings of this study. Finally, the results of this sub-metered lighting data could address uncertainty in the selection of lighting power density and associated schedules of building energy simulations. Keywords lighting retrofit, energy efficiency measures, light switches, building management system, occupant feedback Article History Received: 13 September 2016 Revised: 18 November 2016 Accepted: 29 November 2016 © Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2016 1 Introduction The 2013 U.S. Energy Information Administration (EIA) report indicates that the lighting energy consumption in commercial buildings accounts for 16.4% of the total energy consumption of buildings with 2.91 quadrillion Btu (EIA 2013). The results of the 2003 Commercial Building Energy Consumption Survey (CBECS) show that among the com- mercial building types, office buildings with 20.2% of the total electricity consumption are the primary contributor to the electricity consumption of commercial buildings in the U.S. For these office buildings, 39% of the electricity consumption is associated with lighting consumption (EIA 2011; Salimifard 2014). With improvements in the efficiency of lighting fixtures and incorporating control strategies, e.g. occupancy and vacancy sensors, there are opportunities to save up to 75% (DOE 2016b). These patterns suggest that there is a need to implement Energy Efficiency Measures (EEMs) to retrofit current lighting fixtures in the existing buildings. New initiatives such as the Interior Lighting Campaign (ILC) for Better Buildings (DOE 2015) aims to upgrade the efficiency of current lighting fixtures and plans to save over $2 billion electricity cost annually. The U.S. Department of Energy (DOE) is continuously supporting research projects to provide high quality and energy efficient generation of Light-Emitting Diode (LED) and Organic Light-Emitting Diode (OLED) lighting products (DOE 2016a). These initia- tives mainly target the current lighting fixtures. To enable these projected savings and provide additional opportunities BUILD SIMUL DOI 10.1007/s12273-016-0345-9