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Algorithms

New Cost-Responsive SAT Control Algorithm for VAV Systems Achieves Higher Energy Cost Savings

Strategic Insights

— 2 min read

Research conducted at the University of California Berkeley has developed a new cost-responsive (CORE) supply air temperature (SAT) control algorithm for variable air volume (VAV) systems, which has been shown to achieve higher energy cost savings than existing control strategies. The study assessed energy cost savings of the new CORE control algorithm against other widely adopted control strategies, including the best industry practice ASHRAE Guideline 36 (G36), using a representative office building model. The research found that the new CORE algorithm consistently yielded higher energy cost savings than other control algorithms, with a mean reduction of approximately 4% (0.8-6.9%) in energy costs compared to G36 across all simulated cases.

Key Takeaways:

  • The new CORE SAT control algorithm is designed for VAV systems and does not require discharge air temperature data for easier implementation.
  • The algorithm consists of a cost-responsive control strategy that constrains the maximum SAT based on outdoor dewpoint temperature to meet dehumidification requirements in humid climates.
  • The research used a representative office building model to assess energy cost savings of the new CORE control algorithm against other widely adopted control strategies, including G36.
  • The simulated cases varied in climate, energy tariff structure, and building design and operation.
  • The new CORE algorithm achieved higher energy cost savings in milder climates, with savings of approximately 7% (6.3-7.1%) compared to G36 and approximately 31% (26.8-36.0%) compared to the worst-performing fixed SAT strategy for Oakland.
  • In more extreme climates with fewer economizer hours and dehumidification constraints, energy cost savings of the new CORE algorithm were diminished, with savings of approximately 0.6% (0.2-0.7%) relative to G36 and approximately 5.4% (4.3-6.2%) relative to the least effective Warmest SAT strategy for New York City.
  • The research concluded that the new CORE SAT control strategy has the potential to reduce HVAC operating costs while maintaining occupant comfort.
  • The study found that climatic conditions had a significant impact on the control performance, with milder climates resulting in higher energy cost savings.

Statistics:

  • Mean energy cost savings of the new CORE algorithm compared to G36: approximately 4% (0.8-6.9%) across all simulated cases.
  • Energy cost savings of the new CORE algorithm in milder climates: approximately 7% (6.3-7.1%) compared to G36.
  • Energy cost savings of the new CORE algorithm in extreme climates: approximately 0.6% (0.2-0.7%) relative to G36.
  • Reduction in energy costs achieved by the new CORE algorithm in Oakland: approximately 31% (26.8-36.0%) compared to the worst-performing fixed SAT strategy.
  • Reduction in energy costs achieved by the new CORE algorithm in New York City: approximately 5.4% (4.3-6.2%) relative to the least effective Warmest SAT strategy.

Sources:

  • Simulation-based Evaluation of Cost-responsive Supply Air Temperature Control Strategy for Office Buildings Across Different Climates. Energy and Buildings, 2025;338.
  • Elsevier Science Sa, PO Box 564, 1001 Lausanne, Switzerland. (Elsevier - www.elsevier.com; Energy and Buildings - www.journals.elsevier.com/energy-and-buildings/)
  • Yan Wang, University of California Berkeley, Ctr Built Environm, Berkeley, CA 94720, United States.
  • Paul Raftery, Carlos Duarte, Rupam Singla, Tharanga Jayarathne, and Curtis Fong.

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