I’ve been trying to teach my 5-year-old son a bit about saving energy.

“Please turn the [insert appliance of choice here] off when you’re done using it,” I’ll remind him. “It costs money to leave it on.”

He’ll obediently turn whatever it is off, but being 5, will usually comment or ask a question, from the curious, “What’s energy? Where does it come from?” to the bratty, “Why do I have to turn it off?”

Then, one day, after I had repeated my reminder to turn off the light, he paused and asked me, “How much money will it save?” He had just put a few coins in his piggy bank earlier that day and was having fun figuring out how much he had saved up. I drew a blank. I had no idea.

And that’s one of the biggest problems with energy efficiency today. Of course, everyone loves the idea of energy efficiency. Who wouldn’t want to save the environment while saving a buck or two? But measuring it has always been notoriously problematic, relying on complicated models and engineering studies that don’t reflect real-world conditions to project energy savings. The resulting estimates often are overly optimistic. This is bad because policymakers rely on such estimates to help form various programs — programs that wind up not being nearly as cost-effective as predicted.

In stark contrast is the groundbreaking, meticulously designed study performed by a team of some of the pool industry’s finest, including Steve Barnes, Jeff Farlow and Steve Easley, among others. The goal of the study was to test if variable-speed pumps could offer energy savings while maintaining water quality in commercial pools. Health officials have long resisted VSPs in public pools under a common misconception that low flow rates and high bather loads are simply incompatible with water quality. The 3-year-long study, which involved retrofitting 22 city pools in San Antonio, produced astonishing results. Another major benefit: Analysis of pre-retrofit measurements enabled the team to accurately predict energy savings, a remarkable feat in the world of energy efficiency.

But energy efficiency is not all complicated. In “Efficient Retail,” Stephanie Mills discusses effective ways retailers can sell energy-efficient products, from proper product placement and signage to suggested customer conversation starters for your employees.