Ethan Schussler built his first tree house at 12 years old. His tree house in Sandpoint, Idaho, sits 30 feet above the ground and can be accessed by an "elevator" consisting of a bicycle that, when pedaled, ascends a pulley system to the top.

Purple thistles, California poppies, clover, and dandelions have all taken root in the roughly 10-inch-deep, lightweight humus and grape-husk soil in this 580-square-foot green roof. Designer Peter Liang says that he "wanted to plant a green roof for its thermal mass, but I wanted it to be as natural as possible."

Airstream’s Flying Cloud 30FB Office travel trailer includes a designated workspace in the back corner.

Suzanne and Brooks Kelley at the back of their 1,100-square-foot guest cottage.

The owners toured this home, which surrounds a mature tipu tipu tree, while visiting relatives for the day. The brick is original to the 1947 construction.

Sliding doors by Quantum were made to look like the original panes that couldn't be saved, and they lead to a fire pit outside.

At the top of the stairwell, a sitting area is outfitted with a vintage Eames lounge, a large Jack Goldstein painting, and a 1970s light fixture found by Marcovitz in Paris.

The view!

The kitchen features a concrete island topped with marble. Deja-Vu stools by Naoto Fukasawa surround the island. A print by Guy Gormley, as well as a painting bought during holiday in St. Tropez, hang on the walls.

The design team restored the existing wood beams, giving nod to the home’s former rustic life, while introducing big windows, white walls, and clean lines.

Bay Point Landing offers cabin and Airstream accommodations, RV sites, a communal clubhouse, an indoor saltwater pool, an event hall, a private beach—and plenty of open spaces for surfing, whale watching, crabbing, fishing, or hiking.

The upper floor of one of the cabins features a wood-burning stove, beanbag chairs, and a hanging paper lantern.

Take a look at some of the most exciting, sustainable buildings around the world, and you may notice something they have in common: green roofs, or rooftops covered with a thin layer of soil to allow for grasses and other low-lying plants to grow.

New Depths Inspired by a local winery, George Kyprianou wanted a glass top on his subterranean wine cellar. The interior is lit, casting soft light into the living space at night and revealing the 132-year-old stone foundation. The three-quarter-inch glass lid sits flush with the floorboards; it opens with an ingenious device that Kyprianou devised using a 12-volt air compressor and a remote-controlled switch. When you push the button, the glass lifts just enough to be removed by hand.

Light Box Peter created a simple uplight at the top of the wood box by wiring together energy-efficient fluorescent fixtures typically used under cabinets and countertops. “The cheaper magnetic models hum unacceptably loudly, so make sure you get the electronic ballast types,” he warns. He then painted the cavity white to reflect light and covered them with quarter-inch-thick acrylic from TAP Plastics. homedepot.com tapplastics.com

The view of Kapiti Island is fully revealed from the tower.

“A building can have far greater impact than the space it stands in.”—William Carpenter, architect and resident

The Jorgensen's Menlo Park home is a model of green design with features that are smart for everyone to consider. "Every project is different, but there are some universal things that will apply from project to project," says Feldman about designing a green home. "The first—and most obvious thing—is to always try to build less, to have a smaller house and be smart about how the rooms are designed and oriented so that you can get by with less space. Smart design will lead to a smaller building, but it won't feel smaller."

New zoning allowed for a zero-lot-line structure, but required a public storefront, which Carpenter uses as an art gallery.

The top container contains Wardell's office—and a "napping nook" above that.

In the dining area, a one-of-a-kind table with a reclaimed Carrara marble top by NET—themultidisciplinary design firm of architect Alejandro Sticotti, with whom Nicolas works—is surrounded by prototypes of the company’s Board chair. The family dog, China, sits on a floor made of travertine tiles.

The backyard evokes the serenity of a Japanese Zen garden with a beautiful leaning tree and a shou sugi ban shed.

The architects added a small circular skylight to serve as a vertical focal point in the center of the fifth floor. The quarter-sawn white oak risers produce a beautiful rippled grain highlighted by the abundant natural light.

Rian and Melissa Jorgensen's 2 Bar House in Menlo Park boasts all the usual green design suspects: energy-efficient lighting, good insulation, renewable material finishes, radiant heat, and the roof is pre-wired for future PV panels. Executed by Feldman Architecture, the house requires only natural lighting during the day which keeps energy costs way down. Still, the most stunning aspect of the green design is the living roof planted with succulents, aloe, viviums, and ice plants. "I'm absolutely glad that we did it," says Melissa. "It turned out so well and I really enjoy sitting up there and taking advantage of it as much as I can. It's very peaceful." Read more about this total remodel here.

The countertops in the kitchen are a mix of quartz surfaces and custom and salvaged stainless steel. "We use the kitchen all of the time, it turned out really nice," says Melissa. "It's very open, certainly one of the central focuses of the house, and is fun for entertaining."

The living room, dining room and kitchen are in one open space. The flooring is bamboo. The cabinetry is a mix of bamboo, walnut, and maple, and was fabricated by City Cabinetmakers out of San Francisco.

The Kelleys furnished the cottage with help from Suzanne’s daughter Betsy Burbank of Betsy Burbank Interiors. Classic modernist icons, such as a Saarinen Womb chair for Knoll, a Herman Miller Eames lounge chair, and an Eileen Grey E1027 side table look at home alongside present-day pieces such as an Encore sofa (which handily folds down into a sleeping surface) from Room & Board and a Doka rug designed and produced by Stephanie Odegard. The Wohlert pendant lights from Louis Poulsen were designed by Vilhelm Wohlert in 1959, but grouped as such, they appear distinctly contemporary.

The yellow North Face tent looms over the top of the main building.

Yvette, Adrian, and their son Julian survey the view from the top-floor terrace. “I’ve never been fond of modernism—I find it cold,” Adrian admits. “But having this house, I have to say, it’s growing on me.”

Still, it’s possible to remove or relocate non-structural walls in a home with good bones.

The master bedroom occupies a private space on the top floor.

Milan saw the launch of wrong.london, an offshoot of HAY that's run by creative director Sebastian Wrong. The lighting-focused division released these veneered-oak lampshades, dubbed 30degree, among other designs.

A Nelson jewelry cabinet and Massimo Vignelli lamp.