Energy Manager

Lighting efficiency series: Commercial CFLs – application vs. solution

The introduction of high output compact fluorescents (CFLs) for commercial applications has created quite a buzz in the market as an inexpensive alternative to replacing a customer’s existing metal halide fixtures. The appeal is enticing; why not simply screw in a CFL lamp in place of a metal halide lamp to generate savings of over 50 per cent in energy costs? Sounds like a no-brainer, but is it? The answer is not so simple, but to paraphrase Spock from the USS Enterprise: It’s really quite logical.

June 3, 2009  By Greg Jones

When it comes to cost saving through energy efficient lighting, the savings are highly quantifiable and mathematically indisputable. Savings are a direct result of the time of use (operating hours) multiplied by the wattage (power consumption) of the fixture and lamp. For example: Replacing a 400-watt metal halide fixture consuming 455 watts (Lamp + ballast) with a 220-watt CFL will save 235 watts, over 50 per cent in savings. That’s the indisputable good news.

Where the calculations get a bit more complex is when maintenance costs are factored in. This is why product selection is key — particularly, matching the appropriate fixture to the application. There’s no point in installing a retrofit solution offering the lowest capital cost if the same solution is going to cost more in the near term.  Therefore, understanding the impact on replacement cost/maintenance cost is crucial to ensuring maximum annual savings.

Maintenance costs are primarily tied to the expected lamp/ballast life of the product. When the lamp/ballast fails it must be replaced. Purchasing replacement products is straightforward; however, the labour cost to install these replacements is highly variable. To keep our discussion simple, we will not apply a cost for labour.

The typical lamp life for a commercial CFL is about 10,000 hours. When you compare this to a T8 lamp lasting 36,000 hours, or a T5 at 20,000 hours — or induction lighting at 80,000+ hours — you can begin to match product solutions to applications. Operating hours typically dictate product selection. For example, a one-shift plant operating 2,500 hours annually could expect a CFL to last up to four years. That’s a great value with a low capital cost. But what if the operating hours are longer? Does the CFL solution still make sense? Where do you draw the line? Click here to see a graph that compares CFLs with T8 fixtures under various operating hours.


A retailer operating 6,000 hours per year could only expect a CFL to last 1.6 years. Not a great value proposition when the relatively high cost of a replacement CFL is factored in to the equation – plus the cost and inconvenience of replacing the lamp.

We only recommend CFLs to customers with lower operating hours — typically 2,500 hours annually or lower.  Once a customer’s operating hours get above this level, it makes sense to look at alternative solutions such as the T8 and T5.

Greg Jones ( is President of Nexstar Lighting.

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