窗戶：家庭節能妙方

The past week has ushered in the summer most sultry weather to date, but in our household, we like basic fresh air, unconditioned. So we use windows and fans when necessary. In 2007, our heat pump ran a total of 10 days the entire summer. Our total cooling cost for 2007: $20. Cool.

Our primary strategy is windows management. When we know it is going to be a hot day, we close our windows by 9 am to keep in the cool air from the night before and use fans if we need to. When outside goes from 65 to 87, the inside of our house goes from 67 to 78. Very pleasant. 

A residential central-air system uses roughly 3,560 kilowatt hours per season. Assuming seven cents per kwh and 13,000 households in Cedar Falls, if everyone used their central air, residents of Cedar Falls would spend $3.2 million to keep cool.

In contrast, if everyone cooled with fresh-air technology - in our case, 284 kwh per season for fans - the electric-cooling bill for the whole town would be $258,440. Nearly $3 million per year in savings for Cedar Falls.

And if you extend the same ballpark calculation to Black Hawk County, the savings would be $11.5 million per year; for the Des Moines metro area, $42 million; and for the whole state of Iowa, $267 million.

It takes a ton of coal to produce 2,343 kwh of electricity. An average household burns 1.5 tons of coal per season for cooling. A 3,000-pound air conditioner!

Burning 1.5 tons of coal to cool just one house for one summer emits roughly 12 milligrams of mercury. Assuming 12 weeks of cooling, that amounts to one milligram of mercury per week, either here or near whichever power plant that produced our electricity. And that is just for one household.

The Food and Drug Administration's limit on mercury ingestion for a 45 pound child is 0.056 milligrams per week.

Our household also uses another well-proven cutting-edge technology - the linear evaporative solar-drying system - as environmental activist and author Bill McKibben calls it - otherwise known as the clothesline.
Do we really need clothes dryers? They consume 1,440 kwh per year.

Cedar Falls spends $1.3 million on clothes drying every year; Black Hawk County, $5 million; Des Moines metro area, $19 million; and the whole state of Iowa, $117 million, to dry our clothes while warming the planet.

We have a set of clotheslines outside for fresh air to do the work. In winter, we use clotheslines set up in the basement, plus clothes racks.

Adding things up, Cedar Falls residents spend $4.5 million on cooling and clothes drying every year. What would be the community economic impact of retaining a significant portion of that $4.5 million locally?

After looking at actual electricity and natural gas use of numerous homes in my community, I discovered that some homes use eight times more electricity than my household and four times more natural gas. The potential to trim energy waste is tremendous. Acting on that potential will add self-reliance and resilience to our economic vitality.

This is not a technological issue; it is a cultural one. It is a matter of commitment and public policies that encourage massive reduction in energy use.

And that - aggressive energy conservation in homes, businesses, schools, churches, government buildings and transportation - should be the highest priority for local and state government policies. We already know everything we need to know to cut our energy consumption by half, if not more.

{Kamyar Enshayan is a mechanical engineer with graduate training in agriculture, climatology and solar energy. He is director of the Center for Energy and Environmental Education at the University of Northern Iowa. He also serves as a member of the Cedar Falls City Council. Contact: kamyar.enshayan@uni.edu}