When to use: Use to estimate annual energy and cost savings from implementing supply-air-temperature (SAT) and chilled-water-temperature (CHWT) reset sequences (ASHRAE Guideline 36). Raising CHWT improves chiller efficiency (~1.5% per °F), while raising SAT reduces reheat and chiller load (~1% per °F). This is a degree-based rule-of-thumb screening estimate — note that aggressive SAT reset raises airflow and can increase fan energy, partially offsetting cooling savings, so validate large resets with hourly simulation.