Energy Manager

Electrical & Lighting
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
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.