The window for thermal gain in protected areas will be small. The scan will be limited in time for the thermal window to be open. If you plant is controlled by ISO 9000 or insurance requirements at least once every year. Scan the complete electrical system including your switch gear, motor control centres, bus duct work, distribution panels, equipment panels and emergency systems. We are a public utility.
Larger utilities scan twice a year.
Depending on your budget you should at least scan the three phase system, all your substation equipment, all major underground switch gears and all major vaults servicing downtown customers. How effective are IR building envelope scans. Generally we try to place the building under positive air pressure. The scan should cover all sides of the building and some interior shots as well. Some buildings even under positive air pressure unless perfectly balanced will have some areas with negative air pressure.