The Thousand Home Challenge

May 06, 2009
May/June 2009
A version of this article appears in the May/June 2009 issue of Home Energy Magazine.
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On February 10th and 11th, the ACI and Pacific Gas & Electric (PG&E) sponsored a meeting at PG&E’s Stockton, California training center. The purpose of the meeting was to develop a pilot program for the Thousand Home Challenge (THC). Brainchild of sustainability management consultant Bernd Steinmueller, who suggested the idea at the ACI Summit in San Francisco in 2007, and of ACI’s founder and Special Projects Director Linda Wigington and other collaborators, the THC is designed to:
  • Create mechanisms for reducing the total energy consumption of existing homes by 70-90 percent using a performance-based systems approach and readily measurable home performance metrics;
  • Assemble local and regional centers of excellence to promote the goals of the THC; and
  • Stimulate collaborative and creative problem solving among home performance practitioners and other interested parties.
Approximately 75 Northern California building performance contractors, energy specialists, government, utility, and policy specialists, and experts in related fields attended.

Northern California contains climate zones representative of most of the climates in the United States, making it an ideal locale for initiating the THC. The immediate objective of the pilot program is to identify forty diverse homes that are good candidates for significant energy reductions, develop protocols for creating those reductions, modify the homes (and perhaps their occupants’ behaviors) to achieve the reductions, and document a set of best practices that can be applied to homes across North America to achieve similar reductions.

Meeting the Challenge

There are two ways that a home can meet the Thousand Home Challenge: have its total site energy consumption reduced by 75% (Option A), or have the home meet an energy use threshold based on location and a few other simple metrics (Option B).

Final energy use has to be verified by measuring a year’s worth of consumption after the property is upgraded. These criteria for successfully meeting the challenge were designed to:
  • Include all household energy use, both seasonal and baseload;
  • Be simple enough so that everyone can understand them; and
  • Be direct and measurable using common methods like utility and fuel bills.

Energy consumption as defined by the THC includes wood used for fuel but excludes solar hot water and electricity.

Both qualifying options are quantified in an easy-to-use spreadsheet (see Figure 1) developed in advance of the meeting by Wigington, and Mike Blasnik and Judy Roberson, independent energy consultants. In order to meet the 75% reduction threshold, you have to have one year of historical data documenting the home’s energy consumption. This includes both public utility data and information about non-regulated fuels such as propane and wood. All you need to do is enter your annual fuel usage in MMBtu and electricity usage in kWh, and the spreadsheet calculates the 75% reduction threshold. (The spreadsheet contains a handy Energy Unit Conversion Chart to help you convert fossil fuel usage in therms, and wood loads in cords, to MMBtu.) Option A is best suited for households that use a lot of energy.

In order to meet Option B you need to enter your zip code (to identify your local weather data), finished floor area, number of occupants, number of households in the building, and the percentage of the shell shared with other buildings. The spreadsheet calculates your total allowed annual fuel usage in MMBtu and electricity usage in kWh. A second section of the spreadsheet shows how the Option B threshold numbers are calculated and comparisons to the Passive House and EPA Home Energy Yardstick criteria. Option B is best suited for homes that use lower amounts of energy or homes for which there is no historical consumption data.

Launching the Challenge

Meeting participants were asked to participate in a webinar explaining the goals and priorities of the THC and to plug their own home’s data into the THC Calculator prior to attending the meeting. Once assembled, guided by Wigington, the group discussed the nature of the challenge and broad implementation issues. Several hours were devoted to break-out groups that focused on specific topics such as metrics for measuring energy reductions, financing options, the process for choosing the candidate houses, reporting, organizational issues, and much more. Working groups reported back to the full group for questions and further discussion.

The result of this effort was a set of ongoing committees that will screen potential projects and select the first forty homes, work with home performance contractors to upgrade the properties to meet the THC requirements, work with home owners to finance the upgrades, document the processes, measure the results, and identify the successful approaches. In addition, a steering committee was formed to address broad organizational and implementation issues relating to the nature of the THC itself. Although the Thousand Home Challenge is being kick started immediately, and work will begin on candidate houses as soon as possible, the project will be ongoing for many months. It’s expected that this first pilot will stimulate the development of additional programs in other parts of the country.

The Thousand Home Challenge is, at this stage, a unique, primarily volunteer partnership of private individuals and companies that strongly support its goal—significant existing home energy reductions. It’s founded on the assumption that we are currently experiencing a crisis of obsolescence in housing that is having significant, long-term, irreversible, negative impacts on our planet. Net zero energy and carbon neutrality can readily be achieved in existing homes, but it requires a new paradigm in thinking. The Thousand Home Challenge is an attempt to create that new paradigm.  

Steve Mann is a HERS rater, Green Point rater, LEED AP, Certified Energy Analyst, serial remodeler, and longtime software engineer.

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Steve Mann can be contacted at
For information about ACI and the Thousand Home Challenge, visit
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