Frugal living is challenging at times. What seems like a meaningless small change can energize your budget and fire your investments on a steeper trajectory.

Countless blogs and websites provide lists on how to save money. Turn out lights, turn down the heat in winter and the library are good ideas. Mr. Money Mustache has a strong drive to bike. On several occasions he has published on the benefits of biking. Biking is good for your health and cuts energy use. Reducing or eliminating what he calls a “clown-like car habit,” you cut spending by serious coin.

Like many readers I undertake a number of these ideas. I keep my house 60 degrees F in the winter. To keep warm I wrestle Mrs. Accountant and the kids to keep them away from the thermostat. I use natural lighting whenever available.

The farmstead is a whisker more than 15 miles from my office. I bike about 100 days a year. The savings are modest, but noticeable. A 30 mile round trip costs me about $15 according to the IRS mileage rate. My vehicles are purchased used and run for a couple decades before they are replaced so my vehicle cost is less. I estimate my real cost per mile is closer to 30 cents. This means every bike ride to the office allows me to keep an extra $9 in my pocket, tax-free. (You don’t pay an extra tax for not spending money.)

A Lesson from Walmart. Yes, Walmart

Back around 2008 Walmart started to examine its energy costs. The idea was to offer affordable compact fluorescent light bulbs (CFLs) to customers; the thought being CFLs lasted longer so Walmart would soon have more shelf space for other products. The energy savings customers experienced would likely be spent at Walmart on other items.

The discussion eventually turned internal. What if Walmart used CFLs in their stores? One idea was to replace incandescent bulbs with CFLs in the ceiling fans on display. Of the 3,230 stores Walmart had at the time, the average store had ten ceiling fans. Each ceiling fan had four bulbs.

Each bulb produced a minor savings, but when the Law of Large Numbers took hold Walmart stood to reduce their utility bill $6 million per year! Management had an easy decision.

Since then Walmart has expanded their energy philosophy to include utilizing as much natural lighting as possible and electric semis to deliver products to stores around the U.S.

CFLs cost more than incandescent bulbs upfront, but the longer life of the CFL (8-10 times as long) and energy savings more than cover the initial capital outlay. Total savings from reduced energy use is several times the entire upfront cost.

Lesson from a Humble Accountant

My memory is slipping with age. I can’t remember the exact year I transitioned to CFLs and later LEDs. What I can share is how I determined when it was a good idea to make the switch. Regardless the exact date, I was an early adaptor.

We will focus on my office to keep the discussion simple. I used the same thought process to transform my lighting at home.

Lighting is an important consideration in a tax practice. Eyes get tired easy enough looking at a computer screen all days and trying to decipher smudged and faded documents. Security lighting and signage are also important.

The outside of my office building is covered by floodlights and security cameras. The entrance light is always on. Security lights and the sign are on a photovoltaic trigger. This means the two lights at the entrance are on 24/7 and the sign and security lighting average 12 hours of operation per day — more in the winter, less in summer.

I forget the exact wattage used so I’ll stick with 100 watts per bulb when incandescent bulbs were used. My research showed an equivalent CFL used only 26 watts. Each hour of operation used 76 fewer watts per unit.

The hourly savings didn’t amount to much. However, when a light is operating an average of 12 hours a day 365 days a year we get 4,380 hours of annual use. 4,380 hours of use times 76 watts of reduced energy consumption per hour equals 332,880 fewer watts used per year. Reduced energy consumption of 332 kilowatts times $.12 per kilowatt and we save 39.84 per unit! We have twelve units.

The lighting replacements paid for themselves in less than a year! And they lasted longer.

Inside the office we have 40 of those 4-foot tube CFL bulbs. We use as much natural lighting as possible, but we still operate half the light banks most days.

The typical office uses what is called a T12 linear fluorescent bulb. Each bank has two or four bulbs. T12 bulbs use 40 watts.