That change cost Sider about $320 and earned $80 from the city utility. She also added a new refrigerator for $650 and got a rebate of $150 from Pasadena because of the appliance's Energy Star rating.
Both homeowners also employed cotton-fiber insulation, Sider in her attic and Eyster through his entire house, including underneath the structure and between rooms.
Because the material doesn't contain fiberglass, installation doesn't require protective gloves, a respirator or goggles. So Sider and a friend were able to fit the insulation among her attic's beams themselves. That cost her $900 but earned a $130 rebate from Pasadena.
Eyster spent about $5,000 on his material, as opposed to the roughly $2,000 it would have cost for traditional fiberglass insulation, he said.
But because he didn't need special protective gear or skills, installation was much less expensive, bringing the total cost roughly in line with what he would have paid to go the standard route, he said.
In at least one area -- solar power -- the budget-minded Sider is ahead of Eyster.
For most people, the costs of photovoltaic panels are prohibitive, even with generous utility rebates and federal tax credits, said Hall of the Green Building Council.
"There's a huge fad right now for photovoltaic systems, so any luxury home that's considered green almost must have PV on it," Hall said. "The irony is that PV is probably the least cost-effective thing you can do."
Retrofitting a house to run entirely on energy from solar panels isn't cheap, about $40,000 for a 2,000-square-foot property, Hall said.
Eyster designed his roof to accommodate solar panels but is waiting to install them until the price comes down.
But for Sider's under-1,000-square-foot house, the investment in solar was big, but so was the payoff, she said.
Sider's 12 low-profile PV panels take up about one-sixth of her roof. Sider said she paid for only half of the $12,500 system because she received a $4,400 city rebate and a $2,000 federal tax credit.
Now, she said, she uses only about half of the energy the system generates, even after adding a forced-air heating and cooling system to replace an aging, inefficient furnace.
"I have the meter on my back porch, and it's fun to see how much I can save," she said. "I like to see how little I can use."
That's the perfect attitude, said Lockwood, the Santa Monica consultant.
"It is a real disservice to give average Americans the idea that the only way to build an environmental house is in some kind of eco-chic, unattainable, unaffordable way," he said. "That's just not true."