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Metrics Separate Energy Savings Facts from Energy Savings Fiction

Illuminating Lighting Retrofits

In commercial buildings lighting typically consumes 26% and HVAC 23%, roughly half of all energy.

Lighting retrofits we call “low hanging fruit”. This is the least technical, least costly retrofit to gain immediate energy savings. HVAC energy savings are more capital-intensive, more complex and have a lower pay back time.

So, how do we begin? Should we start with a lighting retrofit campaign? Yes and no. Allow this real life story to explain.

An owner of a vary substantial residence in Rockwall County, Texas requested a proposal to reduce electrical consumption of his home. One item that caught my immediate attention was finding of 96 100-Watt incandescent flood lights installed in recessed lighting fixtures. 96 lamps X 100 Watts = 9,600 Watts. Is this not an obvious candidate for a lighting retrofit? Although it appeared so, it was not. Why? The owner never uses them.

We can’t predict energy and dollar savings simply from nameplate wattage. First of all, you pay on consumption, kilowatt-hours, not kilowatts. According to my best calculator, zero times anything comes up zero.

Metrics are key to energy conservation decision making. Let’s apply a rate of $0.087/kilowatt-hour to the above home with those 96 100-Watt lamps.

Assume all 100-Watt lamps were to operate 24 hours per day.

9,600 Watts X 24 hours = 230.4 kWh (kilowatt-hours). At a cost of 8.7 cents per kWh, daily operating cost would be 230.4 kWh X $0.087 = $20.05. If run 30 days, total cost of operation would be $601.34. Do this for one solid year: $7,318.25.

The preceding exercise was an unrealistic evaluation of energy consumption. The point of the exercise is to demonstrate how you can accurately predict with certainty energy consumption of a particular lighting configuration.

Back to those promised savings.

Complex calculations or Excel worksheets easily convince most people, because most  people never use math.

Companies promising energy savings use a variety of marketing tools to persuade potential customers to sign on the dotted line: colored charts, complex calculations, etc.

When a company’s salesperson tells you the company’s actions can save you money, tell them to show you the metrics, the measurements. Demand an accounting. It’s not rocket science. It’s just ordinary arithmetic.

John White
Rockwall Controls Company, Inc.
972.771.3514      office

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