The new rule was approved by Boulder County Commissioners on Tuesday, November 3rd.
The “net zero mandate,” as the energy production requirement is known, is part of the county’s BuildSmart program.
The BuildSmart program was adopted in 2013 under a more general sustainability plan aimed at reducing greenhouse gases and other climate impacts.
Originally the rule applied to homes 8,000 square feet or larger, then it was expanded to 6,000 square feet and larger and now to 5,000 square feet.
Earlier this year, county officials were set to impose the standard to homes 4,000 square feet or larger, but decided not to due to the county’s ongoing efforts to keep home costs from escalating even further.
Boulder has set its sights on having all new homes to meet the “net zero” energy standard by 2022, writes The Denver Post.
The net zero requirement does not apply to existing homes that are being remodeled.
Though estimates differ, building “net zero” houses powered with solar arrays that are large enough to sustain the entire home can add an estimated 15 percent to construction costs, according to dailycamera.com.
For the average Boulder County home, which is about 4,000 square feet and costs roughly $200 a square foot to build, that could add around $120,000 to the cost.