Building Engineering Systems: Water, Sewerage, HVAC, Electrical and Gas
Water and drainage
Water supply design sets the required pressure and flow at each fixture, pipe material (steel, PPR, PE) and insulation against freezing. Sewerage is gravity-driven: the diameter and longitudinal slope must give self-cleansing velocity, stacks must be vented to protect traps, and grease or sand traps are needed where the use demands. Backflow protection and separation of potable and non-potable systems are non-negotiable. Traps: assuming a larger pipe always solves a drainage problem (it lowers velocity), and forgetting venting.
HVAC
Heating and ventilation design starts from heat loss and required air exchange per room type, not from equipment size. Mechanical ventilation, smoke control and fire dampers interact with the fire compartments, and ductwork and suspended equipment must be seismically restrained.
Gas supply
Gas systems are classified by pressure tier, from high-pressure mains down to low-pressure internal piping at appliances. Internal gas piping requires combustion air, flue or chimney evacuation, automatic safety shut-off, leak testing and purging before commissioning. In seismic zones, flexible connections at appliance entry and seismic shut-off valves are expected. Traps: sizing an appliance flue as if it were ventilation, and omitting the shut-off valve.
Electrical
Design covers load calculation and diversity, cable sizing with voltage drop, earthing arrangement (TN-S or TN-C-S), residual-current protection typically 30 mA for socket circuits and wet areas, lightning protection and equipotential bonding. In seismic zones, switchboards, cable trays and luminaires must be fixed to resist horizontal forces.
Rule of thumb
Check every system at the interface with the other systems and with the structure: penetrations, sleeves, fire stopping, seismic bracing and access for maintenance. Most real failures, and most exam distractors, live at these interfaces.