It Really Pays to Go Green

July 22, 2010

CFL Light Bulb

A recent conversation on Linked-In focused on the perception that it costs more to build green, debating whether this is really true or if it is a fallacy that some in the industry work at perpetuating. This got me thinking of an exercise I did a couple of years ago to illustrate the costs associated with going green. It involved the simple act of changing one 100 Watt incandescent light bulb for an equivalent CFL bulb. I looked at the costs of purchasing and operating the bulbs throughout their useful life. The results … well, you’ll have to read on to find out!

Purchase Costs

Looking at the costs to purchase both types of bulbs, the CFL quickly loses ground. An incandescent light bulb costs about 89 cents. A quality CFL can cost between $3 and $4. Let’s say $4. That means the CFL costs about 4.5 times as much as the incandescent! Ouch! When most people talk about the added expense to build green, they usually mention a 1% to 2% increase in costs, not 450%. However, when we look at the useful life of the different bulbs, the CFL lasts about twice as long. So, we would need to purchase 2 incandescents to get the same life span as the one CFL. This reduces the premium to 225%.

Operating Costs

In most introductory courses on green building or energy, we learn that a building incurs most of its costs during the operations phase, as opposed to construction. There are building maintenance costs, energy costs, and the costs of the operations taking place inside (assuming we are talking about a commercial building, this would include labor and manufacturing costs). Here is how the operating costs of the two bulbs pencilled out:

Incandescent bulb – 100 Watts x 5,000 hours x $0.11/kWh = $55.00 to operate over it’s life

CFL bulb – 23 Watts x 10,000 hours x $0.11/kWh = $25.30 to operate over it’s life

It costs 217% more to operate an incandescent bulb over it’s life! And that is just one bulb. Due to the shorter life span of incandescents, it would take two to last as long as one CFL. That means we can save $84.70 in energy costs over the life of one CFL. Now who’s ahead?

Maintenance Costs

I know light bulbs don’t require much maintenance, if at all. However, since we are having to install 2 incandescents to equal the life of one CFL, we will have to take into account changing the light bulb. Usually this wouldn’t take much time or effort, but consider the case of changing a bulb in a fixture that is two stories up, or even at the apex of a vaulted ceiling in a home. This requires both time and energy. Let’s say 10 minutes (this is to find a ladder, place it under the fixture, climb the ladder, gain access to the bulb, remove the bulb, install the new bulb, replace the fixture, climb down the ladder, and put the ladder away). If we say our time is worth $15 an hour, this little exercise costs us $2.55.

And the Winner is ….

I think you know who won. But here is the final score: one 23 Watt CFL costs $29.30 to purchase, operate and maintain; two 100 Watt incandescents cost $114.33 to purchase, operate and maintain. Total savings for changing out 1 light bulb: $85.03. An incandescent costs us 390% more than a comparable CFL!

I know that one light bulb cannot take into account all the complexities of a building and its operation and maintenance. However, I do think that it is an accurate illustration of the cost of going green. In the beginning, the CFL costs more, but it more than makes up for it during its operation and maintenance. We have to look at the overall costs of a project, over its entire operational life, before we make a decision about whether it is worth it to go green. In the end, I think it is a no-brainer.

Photo courtesy of Joe Colburn through a Creative Commons License.



Dawn Killough

has over 15 years experience in the construction industry and is the author of Green Building Design 101, an e-book available from Amazon. She is a LEED AP and Certified Green Building Advisor, and has worked on the LEED Certification of three projects in Salem, Oregon.