  Building energy flexibility has been increasingly demonstrated as a
cost-effective solution to respond to the needs of energy networks, including
electric grids and district cooling and heating systems, improving the
integration of intermittent renewable energy sources. Adjusting zonal
temperature set-points is one of the most promising measures to unlock the
energy flexibility potential of central air conditioning systems in complex
commercial buildings. However, most existing studies focused on quantifying the
energy flexibility on the building level since only building-level energy
consumption is normally metered in commercial buildings. This study aims to
investigate the impacts of temperature set-point adjustment strategies on
zone-level thermal and energy performance by developing a non-intrusive
data-driven load disaggregation method (i.e., a virtual zonal power meter).
Three university buildings in Northern California were selected to test the
proposed load disaggregation method. We found that heterogeneities of energy
use and energy flexibility existed across not only buildings but also air
handling units (AHUs) and zones. Moreover, a small number of zones accounted
for a large amount of energy use and energy flexibility; and the most
energy-intensive zones are not necessarily the most energy-flexible zones. For
the three tested buildings, the top 30% most energy-intensive zones accounted
for around 60% of the total energy use; and the top 30% most energy-flexible
zones provided around 80% of the total energy flexibility. The proposed method
enables the electric grid or district energy system operators to regard the
controlled energy-flexible entities as a fleet of AHUs or zones instead of a
fleet of buildings and helps unlock the possibility for targeted demand
flexibility strategies that balance zone-by-zone energy reduction with
zone-by-zone costs to occupants.
