Mechanical Ventilation-24-25 PDF

MECHANICAL VENTILATION Advance services- sem 7 (24-25) -Pratishta Ramda BSSA VENTILATION IN BASEMENT CARPARKS When cars enter, exit and drive through your enclosed parking garage, they release toxic and non-toxic gases. They...

MECHANICAL VENTILATION Advance services- sem 7 (24-25) -Pratishta Ramda BSSA VENTILATION IN BASEMENT CARPARKS When cars enter, exit and drive through your enclosed parking garage, they release toxic and non-toxic gases. They release unburned fuel and fuel particles, various nitrogen oxides, carbon dioxide, carbon monoxide etc. So ventilation of car parks is important. Also to clear smoke in the event of a fire. Mechanical Extract: For smoke clearance 10 air changes per hour should be extracted. Fan room on site Fan room in basement GRILLS-DIFFUSERS AND REGISTERS Grills that supply fresh air are known as diffusers Grills that extract stale/ used air are known as registers  FR FR FS FR FS FS LEGEND FS Fan Supply FS Room 25m X 25m FR Fan Return Room FS FR FR FS FR Basement Zoning  FAN 6m SUPPLY ROOM 6m 6m 6m LEGEND 6m Return duct 6m (same size) Supply Duct (size reduction) Diffuser FAN Register RETURN ROOM Column Ducting Layout- Herringbone  Return Duct- car exhaust Return duct Register 300mm Return- same size throughout -600x300mm Ducting- 25mx25m zones Supply Duct 450mm 600mm Diffuser- Duct reduction 300x300 mm Supply- size increase every 6 m- 450x300mm(min) Ducts accommodation beams and other services Ducts at Junctions or at turns Diffuser and register locations on ducts Assessing ventilation performance Ventilation performance in buildings can be evaluated from the following four aspects- Does the system provide sufficient ventilation rate as required? Is the overall airflow direction in a building from clean to dirty zones (e.g. isolation rooms or areas of containment, such as a laboratory)? How efficient is the system in delivering the outdoor air to each location in the room? How efficient is the system in removing the airborne pollutants from each location in the room?  Two ways of building ventilation Natural ventilation Mechanical ventilation Single sided ventilation Mechanical supply ventilation supply and extraction through the a fan supplies air to spaces same openings ventilation openings in building’s openings ~4% of floor area envelope are used for extraction less efficient usually used where high ventilation internal door remain closed rates are needed and air has to be heated before entering the room Cross ventilation supply and extraction at the same Mechanical extract ventilation level in the building a fan draws air from spaces good result when wind exists fresh outdoor air enters into rooms internal doors opened or equipped either through the leakage routes of with ventilation grilles building envelope or through ventilation openings in the building envelope Stack ventilation air supply through louvers and Mechanical extract & supply ventilation extracted through chimneys a balanced ventilation system wind not needed it must always include a supply and a return air fan an air heater is almost always installed in the supply air side