Environmental, Mechanical, Electrical, and Plumbing Systems
This domain tests HVAC, lighting, power, plumbing, energy, and acoustics at a schematic level. Questions often ask for sizing checks, code minimums, or coordination impacts.
Core rules
- Cooling load: 1 ton = 12,000 Btu/h; office rule of thumb is 300-400 sf/ton, not 500.
- Ventilation follows ASHRAE 62.1; outdoor air is calculated per person and per area.
- Lighting power density, daylight, and controls affect energy code compliance.
- Plumbing fixture units, water heater sizing, and storm drainage govern plumbing space.
- Electrical design considers voltage drop, panel capacity, and emergency power.
Worked example
A 600-sf office with 10 occupants. Using 350 sf/ton, load = 600/350 = 1.7 tons, so select a 2-ton unit. Ventilation at 5 cfm/person plus 0.06 cfm/sf = 50 + 36 = 86 cfm; the unit must handle that outdoor air. If the ceiling plenum is only 18 in, duct and VAV boxes may not fit; the architect must coordinate a deeper ceiling or a different system.
Traps
Using 500 sf/ton for all occupancies; ignoring outdoor air; sizing electrical by connected load only; forgetting condensate drain.