Tim and Margo Smith opened their San Luis Obispo home Wednesday to show off a state program that helps homeowners make their houses more energy efficient.

Through Energy Upgrade California, the Smiths received a comprehensive energy efficiency audit of their home on Meadow Street, and contractor Troy Spindler performed a series of energy upgrades.

These upgrades included installing new insulation, replacing ducts, air sealing and weatherization, and insulation of the hot water heater and pipes. The work cost $3,560. They received a $1,000 rebate from PG&E and the home now uses 49 percent less energy.

Rebates of up to $4,000 are available, depending on the rate of energy savings. Typically, a homeowner can recoup the upfront cost of the energy retrofit within three years through reduced utility bills, said Colin Clark, senior program manager with Energy Upgrade California.

Margo Smith said the family was motivated to do the upgrade to save money and help the environment. They also have the added benefit that the house is now noticeably warmer.

“We wanted to do our part,” Smith said.

When all the gaps in insulation and leaking ducts are added up, the typical home has the equivalent of a hula hoop-sized hole in the side of a house, Clark said. The county estimates that 90 percent of the homes in the county need some sort of energy retrofit, said County Supervisor Adam Hill.

In addition to saving money and improving comfort, energy audits often uncover safety hazards, Spindler said. For example, the audit of the Smith home showed that the furnace had a small but dangerous gas leak that had remained undetected.

Homeowners interested in learning more about the Energy Upgrade California program can attend a free workshop today from 6 to 7:30 p.m., at the San Luis Obispo Library, 995 Palm St. Register by going to http://sanluisobispo-euc.eventbrite.com.