Section M1601 establishes requirements for mechanical systems in residential buildings. HVAC systems must provide heating, cooling, and ventilation. Heating systems achieve minimum temperatures in occupied spaces during winter. Cooling systems are not mandated but if provided must be designed for efficient operation. Ventilation systems must provide minimum outdoor air to reduce indoor contaminants. Kitchens and bathrooms require exhaust ventilation at specified rates. Appliance ventilation is required, with range hoods exhausting cooking odors and moisture. Dryer vents must discharge outdoors, not into attics or crawlspaces where moisture accumulates. Combustion air is required for combustion appliances to operate safely. Sealed combustion appliances draw air from outdoors, while open combustion appliances draw from interior space. Adequate makeup air must be provided if exhaust ventilation exceeds 15 percent of supply air.