Local codes dictate the ventilation requirements and the need for sprinkler systems. Fire and smoke control systems must be provided. Use of security systems with remote monitoring, and central operations control is increasing. Individual metering and billing is common in most long-term use units, encouraging energy conservation more than central metering where occupants have no incentive to save. Odor control is only practical within a unit and most designs confine odors using pressurized corridors from which makeup air is drawn into each unit.
Most codes prohibit centralized air return.
A relatively low noise level is desired, although a higher level continual noise seems more acceptable than wide variations in noise level. Energy efficiency is increasingly being emphasized. The most efficiency systems are water source and air source heat pumps. Water loop and geothermal heat pump systems have favorable operating costs compared to air cooled unitary, particularly where electric heat is used. In some cases, the sprinkler system is incorporated into the water loop.