By Julie Sheer
Whether it's through energy-efficient windows, reclaimed and local materials, renewable energy sources or special insulation, these homes prove that vacation houses can be attractive as well as eco-friendly.

1. Mini homes in Texas that harvest rainwater

In the drought-prone West, every bit of water helps when it comes to landscaping. This cabin (pictured above) in Llano, Texas, about an hour from Austin, is one of four on the property that use rainwater collection tanks to help irrigate surrounding vegetation. Four couples who've been friends for decades built the 350-square-foot studio cabins, using simple materials like corrugated metal for the exterior and plywood for interior walls.

Architect Matt Garcia helped the friends build structures suited to each family, with a common element: They are low-tech and low-maintenance but don't skimp on design.

2. A Montana cabin surrounded by nature

This vacation retreat at Yellowstone Club in Big Sky, Montana, has serious green-building chops. Completed in 2008, it was southwest Montana's first LEED Platinum-rated home, a designation that means it's resource-efficient — using less water and energy, and reducing greenhouse gas emissions. Built as a vacation home for a family of five, the 2,200-square-foot property sits on 22 acres. A man-made pond is part of a geothermal system that heats the home in winter, using very little energy. A 2-kilowatt solar array provides the home with electricity.

Reclaimed wood, including logs from trees killed by mountain pine beetles, was used throughout the home. Some wood sources were from Montana and Wyoming snow fences, which are used to keep snowdrifts off roads.

All materials came from within a 500-mile radius of the cabin. The green kitchen cabinets were made from a repurposed antique hutch.

3. A well-insulated straw-bale home in Colorado

Straw bales were tightly stacked in a running bond pattern between posts and beams during this Crestone, Colorado, vacation house's construction. The 15-inch-thick bales serve as superb insulation to keep the home warm in winter and cool in summer, essential for the high-altitude location in southern Colorado. The 2,300-square-foot house was built for a couple, their three teenage children and their friends.

The dining area opens onto an outdoor deck by way of a 14-foot-tall glass garage door. The home was sited to take advantage of the sun. "We angled the house not only for the views, but for passive solar gain during the colder months," says Boulder, Colorado, architect Dominique Gettliffe, who designed the home. "During the winter solstice, the sun's light fills the entire house all the way up the steps to the back bedrooms."

Radiant floor heating was built into the concrete, and a wood-burning stove in the living room also provides warmth. Solar panels help heat the home's water.

Straw bales are a popular building material and style in this area of Colorado. "I liked working with the straw-bale material, which has a soft, organic feeling," Gettliffe says. "It's a nice contrast with the glass, so the house is both solid and open, as well as light."

4. Efficiency and a green roof at a Pennsylvania retreat

Thick walls and a green roof help save on energy costs at this Shohola, Pennsylvania, home that serves as a weekend retreat for an ex-Army Reserves captain, his wife and their two kids. The house on top of a hill overlooks the Delaware River.

Architect Jerry Caldari used 2-by-8 studs to give the ceiling height without the need for structural beams. The studs create deep pockets, which were packed with insulation for energy efficiency.

A green roof that holds 12 inches of soil and grass is held up by metal bar joists. The roof creates more insulation that keeps the home warm in winter and cool in summer.

5. Barn design for a Nebraska weekend retreat

Architect Michelle Penn helped two brothers make an energy-efficient weekend country home inspired by a historic barn that was part of the family farm where they grew up, outside Lincoln, Nebraska. The construction incorporated passive-house technologies and, since there was no public water supply available, they decided to recycle greywater and harvest rainwater, following recommendations from Lincoln-Lancaster County's Comprehensive Plan for the City and County.

The walls covered with pine tongue-and-groove paneling have insulation with a high R-value and a very tight building envelope, meaning higher energy efficiency. Low-emissivity passive sun glass on south-facing windows and low-e glass on the rest of the house use the sun's angles to help with temperature control.

Nine 3,600-gallon greywater tanks in the basement treat water from the showers and sinks, which is then used to flush the low-flow toilets.

A whole-house fan helps cool the home. The barn-style doors are closed and locked in the winter to keep out the cold. The chimney effect helps cool the house as well: Hot air rises through the center, goes up to the cupola and then out.

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