The day begins at Lucie Stern Community Center with information sessions from 10:30 a.m. to noon, and 12:30 to 1:45 p.m. Tour maps will be provided until 2:30 p.m.
In addition, plug-in and electric vehicle owners will offer rides, beginning at 10:30 a.m.
This year's tour includes seven homes, including the Palo Alto EcoHome, a mobile demonstration home located behind the Lucie Stern center, according to Mike Balma, development director and board member of SunWork, a nonprofit that installs solar electricity systems on small-energy-footprint homes with the help of trained volunteers.
"Two of the homes are passive designed homes and were completed within the last two years. The other homes have added energy efficiency and solar features to reduce their carbon footprint and reduce their energy bills," he wrote in an email.
Maria and Julian Richardson's real-estate agent finally broke down and bought a compass, to make sure any property she showed them had the exact southern orientation they were seeking to build their zero-net-energy home.
Maria, a physicist and mother of three boys under the age of 12, had been boning up on energy-efficient houses, beginning with Susan Susanka's "The Not So Big House." Once they located the right location, in the Palo Alto hills above Foothill Expressway, they turned to Arkin Tilt Architects, a Berkeley-based firm with expertise in energy-efficient home design.
"Energy efficiency means to minimize the use of energy by first building a smaller house," Maria said. Their plan called for three bedrooms, two full bathrooms and a powder room in 2,400 square feet.
Building a smaller home came naturally to Maria, who grew up in Spain, and Julian, who is from England. "In Europe, things are smaller; here people sprawl," she said.
Next comes siting the structure to minimize energy requirements. "Place the windows where the sun is," she said, noting that they could satisfy up to 75 percent of their energy needs just through appropriate window placement.
"It's easy to be energy efficient when you're only dealing with 25 percent, ... and it's not a 6,000-square-foot house," she said.
The Richardsons did not give up comfort to gain energy efficiency, she said. They disliked forced-air heating and cooling so chose a hydronic system that runs in pipes below their concrete floors. The flooring, which was ground down in places to expose the texture, is something Maria spotted and liked at the California Academy of Sciences in San Francisco. Maria likened the floor to a battery, absorbing heat from the sun during the day and radiating that heat in the evening.
"We built within a magnificent envelope, very tight. This will keep us insulated," she said.
Maria describes her home as a box "with the right holes and right materials," without a lot of bells and whistles.
But she didn't stint on design.
The kitchen/family room features fir cabinets with countertops made of bamboo or stainless steel. One strip was a leftover piece of black stone — perfect for baking — that their architect had in storage. Moorish "cuerva seca" tile in the backsplash comes from southern Spain, harkening back to Maria's country of birth. All the appliances are electric.
The house is essentially U-shaped, built around a paved courtyard. The windows in the center of the U are west-oriented, so in the summer they cover them with slatted shutters via barn-door sliders. In winter, the shutters are open all the time, she said.
Other shade is provided by large overhangs with "shading fins" as well as some mature live oak trees and espaliered fruit trees.
Most people install blinds or shades on the inside of the house, but that lets the sun heat up the glass (and the house), Maria explained. By placing the shades on the outside, the sun never heats the glass.
The exterior of the house is made of fiber-cement panels, with an air gap between them and the wooden skeleton. In the architect's notes, the panels are described as "a fiber-cement rain-screen to minimize thermal transfer while providing an elegant, durable finish." The color is integral, meaning they never have to paint.
The pool is sited so that water temperature is 85 degrees, even without the additional solar heating.
For laundry, the Richardsons chose to install a condensation dryer that vents inside to a pipe that removes the humidity. On non-rainy days, they have a classical clothesline.
Even the hardscape outside reflects the Richardsons desire to conserve energy. Their driveway is made of permeable pavers, which Maria compared to Weetabix cereal for their ability to puff up when absorbing moisture.
With their landscaping less than a year old, the Richardson's largest energy bill is for water, but once the native plants are well-established, that should be cut way back.
Today, they just enjoy watching their meter run backwards.
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For more Home and Real Estate news, visit www.paloaltoonline.com/real_estate.
What: 2013 Solar Homes Tour: The Road to Zero-Net Energy
When: Saturday, Oct. 5, 1 to 5 p.m.
Where: Seven homes in Palo Alto; start at Lucie Stern Community Center, Community Room, 1305 Middlefield Road, Palo Alto
Cost: $10 donation ($15 families)
Info: www.cityofpaloalto.org or 650-329-2241; http://2013solarhomestour.eventbrite.com/
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