Heat season

Heat season is the annually recurring period during which owners of residential buildings must maintain minimum indoor temperatures — daytime standards keyed to outdoor conditions, nighttime standards regardless — under the housing-maintenance rules. Hot water is required year-round. The obligations attach to tenanted residential space and are enforced through complaints, inspections, and violations at the hazardous classes.

Heat and hot-water complaints are the highest-volume category in housing enforcement, which makes their patterns readable: a building whose every winter produces complaint clusters and heat violations is describing its boiler, its fuel payments, or its management — the records rarely say which, but they say when, how often, and how it resolved.