17 Qfresh air = (0.3l/s/m2 + 2.5l/s/person × 0.057person/m2) × 4935 m2 = 2.2m3/s Equ 1-1 with 1m3 =1000l. This means that the building roughly requires the content of a British red telephone box per second to enter and leave the building (Fig 1.6). Such copious amounts of air can be delivered by a combination of infiltration, natural and mechanical ventilation. Infiltration happens via accidental cracks in the building envelope and should be reduced as much as possible, especially in new construction. Natural ventilations corresponds to deliberate outside air exchange through opened windows and doors. Mechanical ventilation happens via electric fans that deliver outdoor and exhaust return air, usually via a network of ducts. A natural ventilation concept has various benefits from simplicity and reduced costs to giving occupants agency over their fresh air supply. There are however several factors that determine whether natural ventilation is at all feasible in a building. Starting off, all floor plans have to be narrow enough for the air to reach all indoor spaces. As a rule of thumb, the maximum depth of a natural ventilated buildings is about five times the floor-to-floor height. Second, the outside air needs to be pollutant free all year round, a requirement that may be compromised by recurring nearby wildfires, heavy Supply fresh air Exhaust air 2.2m3/s 2.2m3/s Fig 1.6 The Medium Office Boston requires the equivalent of British telephone booth of air to enter and leave the building every second
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