Building Services and Environmental Systems (mechanical, electrical, plumbing)
Services questions are usually numerical or code-based and are spread over مبحث ۱۴ (heating and ventilation), مبحث ۱۶ (water and drainage), مبحث ۱۷ (gas), مبحث ۱۳ (electrical), مبحث ۱۵ (lifts) and the fire-protection requirements of مبحث ۳.
Core rules
- Water: size the rising main for the fixture units served and check residual pressure at the highest, most remote fixture; keep a house tank and pump set where mains pressure is unreliable.
- Drainage runs by gravity: specify slope by pipe diameter, provide a vent stack, and avoid long horizontal runs to the stack.
- Heating: radiator or underfloor output is sized from room heat loss in watts, not from floor area alone; the boiler room needs combustion air and a chimney terminating above the roof zone.
- Gas (مبحث ۱۷): pipes must not pass through bedrooms or unventilated shafts, and every appliance needs a proper flue.
- Electrical (مبحث ۱۳): separate circuits for lighting, sockets and heavy appliances, with RCD protection (کلید محافظ جان) and earthing; lighting levels differ by room use.
- Lifts (مبحث ۱۵): shaft, pit and overhead clearance are architectural decisions and must appear on the plan.
Worked example
Light a 60 m² teaching room to 300 lux using 4000 lm luminaires, coefficient of utilisation 0.6, maintenance factor 0.8. N = (E × A) / (Φ × CU × MF) = (300 × 60) / (4000 × 0.6 × 0.8) = 18000 / 1920 = 9.4, so specify 10 luminaires on a layout that avoids dark corners. Note the logic: lux is maintained illuminance, so the maintenance factor is applied to the luminaire output, not to the target level.
Traps
- Placing a lift or shaft without pit or overhead space.
- Venting a bathroom into a light well with no makeup air.
- Sizing a water heater by volume while ignoring recovery rate.
- Treating gas flue distance from windows as a detail rather than a code dimension.