Ames Electric Department

Prime Time Power
Hot summer weather will be here before we know it. (Promise!) Now is a good time to sign up for Prime Time Power. In return for allowing the City of Ames Electric Services to control your central air conditioner (seven minutes out of 30) during peak demand times, you will receive a $5 credit for each of four summer months.

Call your Energy Services Coordinator, Steve Wilson, at 239-5177 for an application, or for more information about Prime Time Power. A Prime Time Power application is also available at the Utility Customer Service office at 515 Clark Ave., and on-line.

Ask Steve, the Energy Guy

Q: What are Degree Days and how are they used?
A. Degree Days help us understand the impact weather has on energy use. Degree Days are calculated by taking the difference between 65°F and the daily temperature mean (high temperature plus low temperature divided by two).

Example: The high temperature for a particular day was 30°F and the low temperature was 6°F. The temperature mean for that day was:

(30°F + 6°F) / 2 = 18°F

Because the result is below 65°F:

65 - 18 = 47 Heating Degree Days

If the temperature mean is above 65°F, we subtract 65 from the mean and the result is called Cooling Degree Days because we would have to cool the resulting temperature to get back to 65°F. If the temperature mean is below 65°F, we subtract the mean from 65 and the result is called Heating Degree Days because we would have to heat the resulting temperature to get back to 65°F.

If you want to know if the attic insulation you added over the summer is saving energy, you could use your energy bills to determine how many units of heating energy (gas therms, gallons of propane, or electric kWh’s) were used before and after the retrofit. Divide the energy units by the Degree Days. If all other things are equal, the impact of the insulation should cause the "after units" per Degree Day to be lower.

Example:

· Before Units from your bill: January 2002 = 300 therms

· After Units from your bill: January 2003 = 375 therms

· January 2002 Heating Degree Days = 1030

· January 2003 Heating Degree Days = 1342

Before: 300/1030 = .29

After: 375/1342 = .28

In this example, even though January 2003 was colder (more Heating Degree Days), the units per Degree Day went down meaning the insulation is doing its job.

You can find Degree Days for Ames and more information at www.cityofames.org/ElectricWeb.