Responding to Japan's love of pets, several architects have established a new, niche trend within their industry: pet-friendly home design.
With the world's lowest birthrate -- an estimated 7.3 births for every 1,000 people -- Japan is home to many young couples who choose pets in lieu of children. Additionally, many older couples in Japan revere dogs and cats.
"For people who have pets, they're like family," said Akira Koyama, the owner and representative director of Tokyo-based Key Operation Inc., an architecture firm.
And there is a market for pet-focused design, said Koyama, who designed a residence dubbed "House Taishido," or "Cat House."
Located in a densely populated urban district west of Tokyo, the three-story, 30-square-meter home features stepping-stone-like shelves that allow the home's feline resident to navigate vertically in and out of the main living room via small openings.
The small openings in the wall lead to other rooms on the first floor.
The cat can also access the second floor of the unit by walking up the shelves and slipping through a slot that functions as a cat-only portal. Freeing up the unit's staircase from cat traffic allows the space to double as a home library, with bookcases and space for reading.
See 10 Solar Decathlon Homes That Will Knock Your Lights Out
Cat Houses: A Trend That Gives Us Pause
The Appalachian State University team designed a home, "The Solar Homestead," that uses "outbuilding modules" that serve as independent solar collection cells and are based on the lean-to sheds that were common to traditional Appalachian homesteads. The outbuilding area, whose modules collect and convey renewable energy, can be used as a porch, outdoor kitchen, guest room, carport or storage shed.
Team Canada's "TRTL" (Technological Residence that respects Traditional Living) offers two bedrooms and a large dining-cooking area and is outfitted with cutting-edge green techonlogy. Built with materials resistant to mold and fire, the design of the house's exterior pays homage to traditional homes of indigenous communities native to the area of Alberta, Canada.
Made up of the University of South Florida, Florida State University, the University of Central Florida, and the University of Florida, Team Florida is fielding the "FLeX house," a home designed to suit the hot and humid climates of the schools' home state. Its name refers to the home's spatial flexibility: inhabitants may adjust moveable components to rearrange its layout.
The University of Illinois returns to the competition with the" Re_home," a house designed to be a more sustainable housing option for natural disaster victims. The home is about 1,000 square-feet, uses low-cost materials, can be assembled within hours and - with its solar-power apparatus - ensures immediate power supply to victims who might otherwise be left without electricity in the aftermath of a disaster.
Paying special attention to affordability, Team China's home, the "Y Container" fits together shipping containers to create a Y-shaped structure. The home, capped with solar panels, features a deck that collects water, super-insulating materials and air ventilation, all of which reduce energy costs.
The Southern California Institute of Architecture and California Institute of Technology teamed up to create "CHIP," short for Compact House Infinite Possibilities, which gleefully departs from any recognizable style of home. Wrapped in a skin of "outsulation" that makes the home airtight and water-resistant and capped by solar panels, the home's interior is terraced to create a bed-groom-dress-eat-live-work progression that you walk up and walk down to begin and end your day. The home is outfitted with technology that uses excess heat to boil hot water and also has an automation system that displays exact measurements of the home's energy usage.
Designed by Hampton and Old Dominion universities, who have partnered for the competition, the Unit 6 "Unplugged" aspires to encapsulate the "Arts and Crafts" character of homes native to Norfolk, Va. One of the home's most distinctive features is its sunspace, which functions as a porch in the summer and heat sink in the winter.
Comprised of Massachusetts College of Art and Design and the University of Massachusetts at Lowell, Team Massachusetts' entry is a compact, energy-efficient home designed to accommodate a family of three. The "4D" home tips its hat to time by taking into account the changes families go through over the years. Moving walls allow inhabitants to re-structure the home's interior to suit their needs. For example, if a child moves out of the house, his parents may eliminate his room. The solar trellis outside provides shade for the house in addition to supporting a solar array. The team plans to sell the house for a reduced price after the competition.
Coming from an institution that has committed to being carbon-neutral by 2016, Middlebury's team used exclusively natural building materials like sustainably harvested wood, recycled insulation and natural finishes to construct "Self-Reliance," named after the essay by Ralph Waldo Emerson. Influenced by the design of the traditional New England farmhouse, the home is entirely solar-powered, costs less than $250,000 and, though smaller than your average house, makes efficient use of its space to accommodate a family of four.
Catering to Manhattan's concrete jungle, the "Solar Roofpod" is designed to sit atop mid-rise buildings. The home has a solar trellis that supports the solar array and solar thermal collectors that spread heat through a radiant floor system.