Simulating Occupancy in the NIST Net-Zero Energy Residential Test Facility

Abstract

The Net-Zero Energy Residential Test Facility (NZERTF), at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, is a research house that is comparable in size and aesthetic to the houses in the greater Washington DC metro area. The purpose of the NZERTF is to demonstrate the feasibility of achieving net zero energy over the course a year (i.e., energy generated using photovoltaic modules and a solar hot water system equals energy consumed). The lifestyle choices of the occupants can have a substantial effect on the overall energy consumption of the house. As a laboratory facility, a methodology was needed to simulate the occupants' behavior. The occupancy in the NZERTF is emulated by a virtual family of four whose behavior and activities are based on recommendations published by the U.S. Department of Energy. In order to attempt to realistically emulate the daily activities of the virtual family it is necessary to replicate their occupancy profiles, water usage, lighting usage, miscellaneous electric plug loads, cooking loads, appliances loads, and sensible and latent loads. This paper discusses the methodology, strategy, and hardware behind emulating the occupancy in the NZERTF. KeywordsNet zero energy house; net zero energy residential test facility; occupancy profile; occupancy schedule; occupancy emulation; daily occupancy emulation schedule iv

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“…A minute-by-minute occupancy, lighting, and device usage schedule for each virtual family member is based upon a 7 day detailed narrative as presented in Omar and Bushby [18] and summarized by Kneifel [19]. Both parents were assumed to leave the house at 8:30 a.m. and return at 6:00 p.m.…”

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“…Measured electricity consumption during the demonstration phase combined with the load profiles from Hendron and Engebrecht (2010) in Figure 3-4 are used to reverse engineer the peak wattage for the operation of the refrigerator, clothes washer, clothes dryer, range (combination of oven, cooktop, and range hood), dishwasher, and MELs (split across the 1 st and 2 nd floor). Although this method varies from the detailed narrative defined in Omar and Bushby (2013) and the associated assumptions made in (Kneifel, Payne et al 2015), the estimated annual electricity consumption due to plug loads is 4214 kWh, which is similar to the predicted (4231 kWh) and measured (4307 kWh) consumption in Kneifel, Payne et al (2015) 3.6 Heating, Ventilation, and Air Conditioning (HVAC)…”