Diversity factor is the ratio of non coincident peak demand to coincident peak demand, expressed as a decimal between 0 and 1.0. This factor quantifies the reduction in actual demand compared to assuming all zones peak simultaneously. A diversity factor of 0.70 means actual peak demand is 70 percent of the sum of individual zone peaks, reflecting realistic load distribution throughout the day.
Calculation and Values
Diversity factor equals coincident peak divided by non coincident peak. If a building’s non coincident peak is 100 tons and coincident peak is 70 tons, the diversity factor is 0.70. Typical commercial buildings range from 0.65 to 0.85 depending on occupancy patterns, building orientation, and schedule diversity. Residential buildings often show higher diversity factors (0.80 to 0.95) due to distributed occupancy, while data centers show lower values (0.40 to 0.60) from concentrated cooling loads. ASHRAE publications provide diversity factor ranges for different building types and occupancies.
Equipment Sizing Benefits
Applying appropriate diversity factors enables right-sized chiller, boiler, and electrical service selection. Conservative estimates use lower diversity factors (0.65 to 0.70), while optimized designs justify detailed analysis to support higher diversity factors (0.80 to 0.85).
Economic Impact
Every 0.10 increase in diversity factor reduces central plant capacity requirements by approximately 10 to 15 percent, generating significant capital savings in large commercial projects while maintaining reliable operation.