Example #1: Reduced Maintenance Material Costs
Assume you turn off a lighting system 25% of the time. If lights are used 25% less, the lighting ballasts (and lamps) should last about 25% longer. Let’s calculate the impact on the ballast material first:
A ballast life is rated for 60,000 hours of operation. If your building operates the lights 5,000 hours per year, they would need to replace the ballasts at the year twelve. If there are 5,000 ballasts – each costing about $20 in material – then at the twelfth year, the material replacement cost would be:
= ($20/ballast)(5,000 ballasts)
= $100,000
Annualized ballast material replacement cost would be:
= ($100,000)(1/12 years)
= $8,333/year
If the lights are only on for 3,750 hours per year (a 25% reduction), the ballasts should last 16 years. This would reduce the annualized ballast material replacement cost to:
= ($100,000)(1/16 years)
= $6,250/year
Thus, the Annualized Material Savings for ballasts are:
= $8,333/year - $6,250/year
= $2,083/year in ballasts
We can use similar calculations to quantify the reduced maintenance material costs for the lamps:
If there are 10,000 lamps, each costing $2.50 (includes shipping and taxes), and they last 20,000 hours. If lamps are on 5,000 hours per year, then after 4 years they would need to be replaced and this would cost:
= ($2.5/lamp)(10,000 lamps)
= $25,000
The annualized lamp material replacement cost would be:
= ($25,000)(1/4 years)
= $6,250/year
Again, if the lights are only “on” 3,750 hours per year (a 25% reduction), the lamps should last 5.3 years. This would reduce the annualized lamp material replacement cost to:
= ($25,000)(1/5.3 years)
= $4,717/year
Thus, the Annualized Material Savings for lamps are:
= $6,250/year - $4,717/year
= $1,533/year in lamps
Therefore the total annual avoided maintenance material costs (lamps and ballasts) are $2,083 plus $1,533, or $3,616.
This same approach could be used to calculate maintenance material savings values for other ECMs that extend the lives of motors, filters, etc.