Omaha By Design: Omaha, Only Better

by Ken Mayer

I’ve always believed that making good things happen is about individual action. It seems like we expect big problems will be solved merely by complaining loudly. Too often, we behave like children, watching the ads for new toys on TV, making a list for Santa and simply waiting for Christmas.

I don’t believe in Santa anymore, and I’m a bit worried about the fate of the planet. Global warming may be debatable, but it seems to me we ought to do something just in case it turns out to be true. Besides, why not save some money by using less energy?

As I wrote a few months ago, we have taken some action to reduce our energy use here in our little corner of the world. We replaced doors, windows, added insulation, caulked, sealed and put in a more efficient furnace. Most of these changes came with some guarantee of energy savings, some as high as 30%.

Being naturally curious (and maybe a bit suspicious of the claims used to sell me this stuff), I wondered what had happened as a result of all the improvements in our particular house. I went back to our heating costs and took a look, but I soon got confused. Sure, the bills gave details on gas use for the same month last year, but I knew that some months were colder than others, so that wasn’t a good comparison.

After a little research, I found that I could account for the stress put on the heating system by using some information about the weather. I discovered a measure called Heating Degree Days (HDD) that the National Oceanic and Atmospheric Administration keeps track of all over the country. HDD are used to estimate how cold the climate is and how much energy may be needed to keep buildings warm. They are calculated by subtracting the average daily temperature from a balance temperature of 65°.

Barbara Mayes, who describes herself as the “climate person” at the local office of the National Weather Service, was tremendously helpful in supplying daily HDD data collected at Eppley Airfield back to when we moved into our unimproved house in late 2007. The airport is the closest weather station, around four miles north-northeast of the house at roughly 125 feet lower elevation.

Armed with scores of data points, the geek in me kicked in and I started to analyze. First I matched the HDD to the Metropolitan Utilities District (MUD) billing cycle and collected only the gas usage off my bills. MUD makes this easy because you can find all your past bills online.

Next, I calculated the pre-improvements relationship between HDD and gas used. For you other nerds out there, this was done using linear regression. Suffice it to say that, beyond a certain point, the house needed around 13 cubic feet of natural gas for each Heating Degree Day. Using that relationship, I calculated how much fuel it would take to heat the house for the same period the next year, after the improvements had been put in place. The graph below shows what the pre-improvements usage pattern would have been versus the gas actually used during the same months a year later. The actual usage bounces around a bit because MUD doesn’t actually read the meter every month, rather, they bill based on an estimate.

The bottom line here is that the house would likely have used about 665 CCF (Hundred Cubic Feet) of gas during the winter of 2009 if no improvements had been made. Instead, the actual use was only 456 CCF. That’s a savings of 31.5%!

Yes, you read that right. Taking temperature into account, we reduced our natural gas use by nearly a third.

Of course, this analysis doesn’t take into account the effect of wind or snow, heating water or incinerating a hunk of animal flesh on the grill, but heating is a major use of natural gas. Our house is only about 20 years old, so I’m even more convinced now that this stuff really works and we all ought to be considering some sealing and caulking, at the very least.

It’s not just we individual homeowners that need to get to work in Omaha. Newsweek magazine’s new “Green Rankings” put only four Omaha companies on the list of its top 500. All ranked in the bottom 250.

We can do better.