Field Study of HVAC Cost Optimized Supply Air Temperature Reset (CORE)

This project demonstrates the development and deployment of Cost Optimized Reset (CORE), a dynamic, cost-responsive supply air temperature reset strategy designed to minimize heating, cooling, and fan energy use in multi-zone variable air volume (VAV) heating, ventilation, and air-conditioning (HVAC) systems. With HVAC energy consumption varying significantly across supply air temperature reset strategies, Cost Optimized Reset offers a solution that optimizes energy use and cost efficiency. The project refined the algorithm for broader adoption in California commercial buildings and evaluated its performance in real-world applications.The research team implemented CORE in four medical office buildings in California and collected and analyzed HVAC energy consumption data. Measurement and verification analysis compared the new strategy to baseline supply air temperature controls, revealing 5 to 22 percent energy savings and 1 to 20 percent cost savings. Energy simulations further demonstrated that CORE could achieve 1 to 30 percent energy savings in buildings with typical loads and airflows, with simplified versions of the algorithm achieving comparable performance, making it accessible to a wider range of buildings.Key advancements to CORE included adding smoothing factors for operational stability, updating calculations to accommodate diverse HVAC systems, and creating versions of the algorithm that function with partial or no zone-level data. The study also emphasized the importance of thorough system evaluations and retro-commissioning to address pre-existing issues, ensuring effective implementation of advanced controls. Additionally, the team recommended integrating CORE into programming libraries offered by building automation system manufacturers to streamline deployment and improve compatibility with other controls.This project highlights the potential of Cost Optimized Reset to enhance energy efficiency and cost savings in commercial buildings, while also identifying pathways for broader adoption and implementation.