Boiler efficiency drops rapidly below 75% load, due to standby losses. Efficiency loss is roughly 1% thermal efficiency less for each 6% capacity reduction, for operation below 50% load.

Losses will be from boiler casing/stack losses, circulating pumps, and piping thermal loss for these hours.

Chiller lock-out below 55 degrees F, in lieu of continuous operation.

Use weather data to determine hours below 55 degrees F when the chiller will now be off, and cooling loads during these times (if any). Estimate savings from chiller efficiency at reduced load for the hours it should have been off.

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