Session: 02-03 Building Management and Control

Paper Number: 107885

107885 - Leveraging HVAC Set Point Changes for Operational Energy Performance Efficiency and Flexibility in Commercial Buildings: Experiments in a Moist Climate Zone 

Commercial building air conditioning represented more than 9% of 2018 global electricity consumption, and this fraction is only expected to grow globally as the impacts of climate change worsen and standards of living increase. Additionally, in 2018 in the US, the median age of the building stock was 37 years with 21% of buildings built before 1960. Energy efficiency upgrades to older buildings can be expensive and slow to implement but are essential for meeting national climate change goals. This work explores opportunities for developing scalable methods for modified operations of as-is air conditioning systems which allow commercial buildings of all ages to participate in demand response initiatives without requiring expensive capital-intensive upgrades. Leveraging the demand response flexibility of air conditioning systems can significantly decrease both the amount of electricity needed by these systems and the amount of greenhouse gas emissions associated with their use. These modified operations can reduce the total amount of electricity consumed as well as consider the differences in carbon intensity of the grid both on a seasonal and daily timescale to avoid using electricity during “dirtier” times. Thus, by being strategic about HVAC operations, large amounts of emissions can be avoided with little to no costs to a site.

In this work, real-world flexibility experiments were conducted in sections of a commercial building at a corporate campus in New Jersey, in US climate zone 5A (Moist Cold). These experiments measured the decrease in cooling load associated with increasing the temperature set point for the air discharged from eight central air handling units (AHU) serving 189,000 square feet. It was found that temperature set point increases of 2°F for the discharge air temperature of these AHUs decreased cooling load between 7-20% per AHU. Experiments were run only on sections of the commercial building and only aggregate building level data was available, thus methodologies to determine impacts of the experiments on only portions of the building from the aggregate data were developed. Results were consistent with simulations reported on in literature and with similar real-world experiments on the Stanford University campus (US climate zone 3C - Marine), but which required zone-level control which were not available at the New Jersey site. These results confirm that it is possible to implement load reduction techniques even in buildings with limited controls which reinforces the large potential for electricity and emissions savings from leveraging these opportunities across the US.

This work is particularly relevant for those buildings that cannot or decide not to implement large scale HVAC system retrofits for improvements in energy efficiency for  any number of reasons including costs. This work allows these commercial buildings to continue to use the equipment already installed in the buildings but still significantly reduce emissions and energy consumption at critical moments for the grid.

Presenting Author: Rebecca Grekin Stanford University

Presenting Author Biography: Rebecca Grekin is a Ph.D. student in the Energy Sciences Engineering department at Stanford University. She got a Masters in the same department in 2022 and graduated from MIT with a Bachelor's in Chemical Engineering in 2019. Rebecca is passionate about using real world data and finding solutions to hard problems in sustainability that have large impact potential.