How do you size a standby generator for a commercial building?

Generator sizing considers: emergency loads required by code (egress lighting, fire pumps, elevators), standby loads for business continuity, motor starting requirements (starting kVA can be 6x running), load sequencing strategy, and altitude/temperature derating. Calculate running load, then add largest motor starting impact. Select generator with adequate continuous rating and transient response capability. Consider fuel storage, emissions permits, and maintenance access in specification.