January 20, 2011 | 9
Part 2: A Little Research Goes a Long Way (see Part 1: Epiphany from up high: Can a suburban family live sustainably?)
Tracking down an energy auditor on the cusp of the 2010 deadline for energy efficiency rebates proved tricky. Yet on a frigid morning in early January, David Pocklington and Shane Matteson of Energy Conservation Solutions found time to probe our house from basement to attic for energy loss.
The purpose of a home energy audit is to measure the amount of power a house consumes and then assess ways to make it more efficient. Our audit would also serve as the kickoff for quantifying my family’s footprint (a thornier endeavor than I originally believed).
Why begin at home? Residences account for approximately 17 percent of the U.S.’s total greenhouse gas emissions. The main culprits are electricity use, boilers and furnaces, and trash, though homes lose varying amounts of energy depending on “tightness.” Tightness is measured in ACH, or air changes per hour. It’s the total volume of air replaced in one hour. High performance homes have an ACH of .35 or less. Standard homes range from .40 to .60 ACH, and older, drafty homes have an ACH of .65 or higher. (Image left – thermal image of basement door)
Our house was built in the 1940’s. In 2007, the previous owner refurbished it, adding a second floor and installing a number of energy efficiency upgrades, including double pane vinyl windows, dual flush toilets (.9 Gpf/1.6 Gpf), spray foam insulation throughout the attic, crawl spaces and exterior walls, and a tankless water heater for the upstairs.
While I hoped the house would be fairly efficient, numbers speak louder than words. That’s why an energy audit comes in handy. After a room-by-room examination, questions about our utility bills, a blower door test depressurizing the house to negative 50 pascals (enough pressure to draw wind through the electric sockets), a thermographic scan with infrared cameras (see pictures) and a duct-blast test, Pocklington and Matteson crunched the numbers.
Click here to enlarge the summary of the results.
An audit’s final report will list home improvement suggestions according to priority level and the corresponding rebates to minimize costs. Our report had one low-priority suggestion: replacing the batt insulation in our basement subfloor with sprayfoam. Without rebates, the estimated cost of the upgrade is $2,802.50. With rebates, the cost would be reduced by $900.00. (Image right – thermal image of back door)
"The reason there isn’t a whole list of high priorities is your home is probably one of the top three or four most efficient homes we’ve seen in the last year," said Matteson.
Smaller (and cheaper) energy efficiency suggestions, included:
* turning down the heat 2 degrees. Each degree saves 2-3% on the heating bill.
* installing high quality weatherstripping and a door sweep to our basement access door.
* insulating the electric sockets.
* reducing water use.
* replacing all lightbulbs with CFLs.
In this first step towards tallying my family’s carbon footprint, I learned that a little research goes a long way. Our electricity provider, Georgia Power, is paying for half of the audit through the Home Performance with Energy Star Program, and there are municipal-level rebates should we insulate the basement with sprayfoam. Perhaps change really does start at home.
Video: Shannon Alderman: Producer, Editor, Writer
About the Author: Robynne Boyd began writing about people and the planet when living barefoot and by campfire on the North Shore of Kauai, Hawaii. Over a decade later and now fully dependent on electricity, she continues this work as an editor for IISD Reporting Services. When not in search of misplaced commas and terser prose, Robynne writes about environment and energy. She lives in Atlanta, Ga.
The views expressed are those of the author and are not necessarily those of Scientific American.