Engineering systems (water supply, sewerage, heating, ventilation, electrical)
Engineering systems (water supply, sewerage, heating, ventilation, electrical)
This domain tests building services: potable water supply, drainage, heating load, ventilation and basic electrical protection. In Mongolia, heating design uses severe outdoor design temperatures and ventilation must control moisture and combustion products in tightly sealed winter buildings.
Core rules
- Water supply: size for flow and pressure; protect against backflow and freezing. Drainage relies on gravity, so pipe slope and venting must be correct.
- Heating load = transmission losses + ventilation/infiltration losses + any process heat; use the design outdoor temperature, not an average.
- Ventilation supplies fresh air and removes moisture, odours and combustion products; kitchens and boiler rooms need specific extraction.
- Electrical: protective earthing, residual-current devices, correct cable sizing and separation from wet areas.
- Commission and balance systems; record test results.
Worked example A room has 18 m² of external wall with U = 0.35 W/(m²·K). Indoor design temperature is 20°C and outdoor design temperature is −30°C, so ΔT = 50 K. Transmission loss = 0.35 × 18 × 50 = 315 W. Ventilation at 30 m³/h with a volumetric heat capacity of 0.33 Wh/(m³·K) gives 0.33 × 30 × 50 = 495 W. Total = 810 W; add a margin for thermal bridging and infiltration. If the designer uses the average winter temperature instead of −30°C, the heating system will be undersized.
Traps that cost marks
- Using average outdoor temperature rather than design temperature.
- Ignoring ventilation and infiltration losses.
- Wrong drainage slope or missing venting.
- Omitting RCD protection in wet areas.