Old lamps IRC  
Op. hours/year 3 000 same  
Lamp life 4 000 same  
Lamp wattages 65W 50W  
Nos. of lamps 300 same  
Price/kW/year SEK0.60 (8cent) same  
Total kWh/year 58 500 45 000  
Lamp cost/pc SEK 30 SEK 40  
Costs for 225 lamps/year 6 750 9 000  
Electr. cost/year 35 100 27 000  
Total op. cost/year 41 850 36 000  
Saving IRC   SEK 5 850 ($780)