Mechanical, Service Water Heating and Lighting Systems
Mechanical systems
Know minimum equipment efficiencies (expressed as rated conditions such as COP, EER, SEER, or kW/ton), economizer requirements by climate and capacity, ventilation and demand-control ventilation, duct insulation and sealing, and controls (setback, optimum start, zone controls). Traps: applying residential efficiency metrics to commercial equipment, ignoring the economizer high-limit shutoff requirement, and confusing minimum efficiency with prescriptive system selection. Piping insulation and simultaneous heating/cooling prohibitions are frequent test items.
Service water heating
Requirements cover equipment efficiency, storage tank insulation, pipe insulation, temperature controls, and circulation pump controls. Recirculating systems need controls to limit pump operation. Traps include treating SWH as part of the HVAC section and missing the separate insulation and control requirements.
Lighting
Lighting is the highest-yield topic. Understand lighting power density (LPD) limits by space type, the whole-building versus space-by-space methods, lighting controls (occupancy/vacancy sensors, time-switch, daylight responsive controls near fenestration), and exit/egress lighting. Traps: mixing the two LPD methods, forgetting that decorative or display lighting may have separate allowances, and missing control requirements triggered by power thresholds or daylight zones.
Worked example
An office of 400 m² has 9 kW of connected lighting. Using a space-by-space LPD limit of 9 W/m², the allowance is 3.6 kW - the design exceeds it by 2.5×. Rule of thumb: compute allowance = area × LPD, then compare connected load; reductions come from controls credits or a different declared method, not from wishful rounding.
Candidate checklist
Match the metric, the method, and the control trigger before answering.