Building Services Engineering 5th Edition Handbook

164 Ventilation and air conditioning
5.22 Shaded window.
6. A department store has 340 people in an area of 35 m × 25 m that is 4 m high. Smoking is
permitted.
(a)
(b)
(c)
(d)
(e)
(f)
Calculate the fresh air quantity required to provide 12.5 l/s per person.
If the air change rate is not to be less than 5 changes/h, find the following.
supply air quantity;
percentage fresh air in the supply duct;
extract air quantity if 85% of the supply air is to be mechanically withdrawn;
recirculated air quantity;
ducted exhaust air quantity.
7. Air enters an office through a 250 mm × 200 mm duct at a velocity of 5 m/s. The room
dimensions are 5 m × 3m× 3 m. Calculate the room air change rate.
8. Show two methods of allowing fresh air to enter a room where extract ventilation is by
mechanical means and the incoming air is not to cause any draughts.
9. Discuss the relative merits of centrifugal and axial flow fans used in ventilation systems for
occupied buildings.
10. Sketch and describe the arrangements for natural and mechanical ventilation of buildings.
State two applications for each system.
11. Describe the operating principles of four different systems of air conditioning. State a suitable
application for each.
12. State, with reasons, the appropriate combinations of natural and mechanical ventilation for
the following: residence, city office block, basement boiler room, industrial kitchen, internal
toilet accommodation, hospital operating theatre, entertainment theatre.
13. Explain, with the aid of sketches, how the external wind environment affects the internal
thermal environment of a building.