Around 10 years ago, private investor Craig Ehrlich set a benchmark for sustainable architecture with his house in Santa Monica, Calif. Designed by John Friedman Alice Kimm Architects, it had the first graywater recycling system in town, a photovoltaic system, radiant heating, and other features that were then state of the art. Because California was a respite from his other life as a jet-setting businessman in Hong Kong, Ehrlich built the house around a garden, emphasizing the nature and tranquility that he sorely missed. A decade later, Ehrlich discovered that his neighbors were moving, and promptly decided to continue his adventures in architecture. “It was the opportunity to expand upon the vision and create more greenery, along with a separate office where I could work strange hours without disturbing my family,” he says.

Ehrlich called up Friedman, FAIA, and Kimm, FAIA, again. “Here in Southern California, we really have the advantage of being able to design for indoor–outdoor living and integrated sustainability,” Friedman says. With that in mind, the architects amped up Ehrlich’s original concept into a two-level guesthouse, with a pool and a lounge area (thus the name, Ehrlich Retreat +). Technically, it is a separate single-family house, with its own kitchen and garage, which provides maximum flexibility for the property down the line. Stylistically and logistically, it forms a compound with the main home, a modern take on the traditional Chinese courtyard dwelling. Friedman and Kimm made sure to hit all the high-performance notes again; the new building has been awarded a LEED for Homes Platinum rating. “We’re quite happy about that,” Kimm says. “Not only is it one of the first single-family homes in Southern California to be LEED for Homes rated, but it came in at the highest level.”

The home also doubles as an immense piece of public art, with a dramatic stuccoed frame that extends well beyond the borders of the second story, causing even jaded Angelenos to stop and gawk. The poised white rectangle has the appeal of classic Modernism, but it is also a critical part of the sustainability story: The frame’s deep overhang helps shield the house’s main southern exposure from the region’s scorching sun. “It shades the interior and defines the whole compound, solving a functional problem in a beautiful, compelling way,” Friedman says. “That’s what architecture is all about—there shouldn’t be a compromise.”

On the ground floor is a double-height office that is aglow with natural light, thanks to a row of large clerestory windows that bring in mellow northern light. “We’ve worked with some of the best sustainable design experts, and they’ll tell you right up front that if you get the building in the right orientation, you’ve done the main part of the job,” Friedman says. Indeed, the new symbol for luxury may be a house that is so thoughtfully designed that you don’t need artificial daytime lighting or climate control. In this case, the lack of an air-conditioning system speaks to the success of the natural ventilation. As in the main house, windows, sliding glass doors, and motorized skylights combine forces to let breezes cool the space.

From their second-story suite, guests have a view overlooking the lawn. It’s also one of the few places you can spy the 3.9-kilowatt photovoltaic system that supplies the house with a substantial portion of its electricity. The solar panels are integrated into the design via a poolside trellis, creating a sheltered lounging spot. “I had wanted to do a PV canopy for a while, to provide both shade and electricity,” Friedman says. “Here, it’s a more traditional wood trellis with panels on top, but you could also make one where the panels themselves form the top of the trellis.” After running into difficulties finding an FSC-certified hardwood, the architects crafted the trellis and wooden screening around the house out of FSC-certified Western red cedar, and stained it to look like mahogany.

As Ehrlich reviews a decade of building—and living—green, he’s surprised that more people aren’t doing the same. “It still frustrates me that more architects and contractors don’t promote this to their clients,” he says. “They either aren’t schooled in it, or they’re afraid it’s going to be too expensive, so it falls upon the client to have a sense of social obligation. But I can tell you from personal experience that it’s a very small incremental cost, and well worth it.”