October 24, 2005

Conservation vs Generation

Posted by Scott at 09:12 PM

I was reading a story in the Nashua Telegraph about a new solar panel installation at Stonyfield Yogurt in Londonderry, NH. This $400,000 installation is now the fifth largest solar array in New England, generating 54 kilowatt hours next year. Impressive, no? The CEO had a telling line:

“Frankly, conservation is a lot more impactful, but we wouldn’t get a bunch of reporters here to look at our new insulation.”

The article clarifies his statement:

[The CEO] estimated that the installation would displace about 1 percent of the electricity use at the plant, which has huge refrigeration needs. By contrast, the extra insulation that Stonyfield has installed in its state-of-the-art refrigerated warehouse will have much more of an effect. But you can’t see it, can’t photograph it glinting in the sun, and can’t get reporters to come and admire it.

The Telegraph's science writer summarizes is succinctly (quoting an EPA official):

“The kilowatt that is not used is the best of all.”

This is something I've been trying to factor into my analysis at home. Given n dollars to spend on energy improvements, what is the best application? While a solar panel array may seem technically sexy, at ~$9000/kilowatt, there are plenty of ways you could first spend that money to save a kilowatt. For most US homes, the first dollars would be best spent in reductions in usage before you work on generation. Boring, yes, but a better way to spend the early money. Sigh.

Our house is well insulated, has two wood pellet stoves, and efficient windows. Our focus this month will be to take three or four of our largest light fixtures and replace their bulbs with compact fluorescents, aka CFs, which use about a quarter to a third of the electricity while lasting much longer. We have several fixtures that take three bulbs each on the first floor (where we spend most of our time). Our finished basement is the worst offender. A single light switch turns on six overhead light bulbs to illuminate it. The problem is that the kids are forever forgetting to turn it off when they come back upstairs. We're seriously considering having an additional control installed at the top of the stairwell so we can reach around and shut them off from upstairs — perhaps sometime next spring.

The thing I've been trying to be careful about is that some CFs look too cold and sterile, unlike their incandescent counterparts. We have a pair of CFs above the kitchen island and Michelle doesn't like them. She says that the lighting reminds her too much of hospital lighting. Given her associations with hospitals, I can understand her reservations. It turns out that when you buy a CF, you need to look at the "color temperature" of the bulb. Anything above about 3500K indicates the bulb will have those sterile, cold, bluish tones that Michelle doesn't like. Ideally you'd want something in the 2500-3000K range to get a rough equivalence to incandescent bulbs.

Hopefully one of these nights this week, on my commute home, I can stop at a hardware store and see what the local shops have. Now if I could just better train the twins to shut lights off...


When Matt was living in his apartment, he used all CFs in his lamps (except for one, and that's because it took little tiny light bulbs and we couldn't find any CFs that came in that size, so that lamp never ever got turned on, it just sorta sat there...)

Matt's been trying to get my parents to switch... I don't see it happening unless we go out and buy the light bulbs and install them in every lamp ourselves....

Posted by: nikkiana at October 24, 2005 10:54 PM

As an apartment dweller, that's actually kind of impressive. Often times you don't end up staying in an apartment long enough to see the return on investment of installing CFs. It's true that they more than pay for themselves both in longer lifespans and reduced energy, but usually you have a hard time making a renter consider them. Kudos to Matt!

For your parents' house, you could go with an incremental approach. It's a lot like what software guys call performance profiling. It's quite often the case that 20% of your code accounts for 80% of the bottlenecks. If you want to double your speed, you focus primarily on that 20%. Why? Because even if you made the remaining 80% *infinitely fast*, it would only make your application 20% faster overall. That's the way we're tackling it. Find the fixtures that are on the most often during the day, especially the multi-bulb fixtures, and go after those first. That's where you get "the most bang for the buck".

Posted by: Scott at October 25, 2005 06:44 AM

David Brooks, author of the article, wrote back to say I should watch for his followup article. It's online now and you can see it at:


It's a fun story about a local Nashua business owner who runs Chicken N' Chips. He bought a used VW diesel Beetle and converted it so that it could run on his used cooking oil. He reduced his waste oil disposal costs and his delivery costs at the same time!

Posted by: Scott at October 26, 2005 09:09 AM

Matt's parents used CFs in their house, so I think Matt picked up the habit of buying them from them.... It wasn't until he was actually paying for electricity on his own that he really picked up on how much money he saved...

My mother's main resistance to switching right now is her stash of lightbulbs... She's got a stash of inefficent light bulbs that she's already bought and wants to use, and she thinks that replacing working light bulbs is a waste of money... AND she bought those light bulbs that are supposed to look like sunlight, so she thinks she's bought specialty light bulbs...

The light bulbs upstairs will be effecient at least....

Posted by: nikkiana at October 26, 2005 09:48 AM