Mechanical ventilation
Some buildings designed with sustainable architecture principles may use airtight technologies to conserve energy. Under some low energy building, passive house, low-energy house, self-sufficient homes, zero energy building, and superinsulation standards, structures must be more air-tight than other lesser standards. Air barriers are not effective if construction joints or service penetrations (holes for pipes, etc.) are not sealed. Airtightness is a measure of the amount of warm (or cool) air that can pass through a structure. Mechanical ventilation system can recover heat before discharging air externally. Green buildings may include windows that combine triple-pane insulated glazing with argon or krypton gas to reduce thermal conductivity and increase efficiency. In landscape and exterior construction projects, airtight seals may be used to protect general services and landscape lighting electrical connections/splices. Airtight implies both waterproof and vapor-proof.