How the ZeroHouse Works

Even though this design is unbuilt, the ambitious zeroHouse was the winner of the Texas Society of Architect's Design Award in 2007. The architect Scott Specht, of Specht Harpman, claims the design will comfortably fit four adults, despite only being 650 square feet. Here's a rundown of the specifications:

If you shy away from making design choices, the zeroHouse might be right for you. As a prefabricated house, many of the furnishings are already picked out and built-in for the owner. These furnishings include:

However, if you want to flash your personal design flair, you'll still have the option to customize your zeroHouse to a certain degree. For instance, you can communicate your preference on certain materials and color patterns, including the exterior color of the house.

In addition to other amenities, the house has an LED lighting system built into the walls and ceilings. These lights are dimmable, but, more importantly, they're high-efficiency. Unlike incandescent light bulbs, they don't convert much of their energy into heat. Rather, more of their energy goes toward emitting light, which saves the house energy for other things.

The structure will require little maintenance. Panels on the outside of the building consist of materials that are scratch and dent resistant. These materials also deter general wear and tear, and to prevent corrosion the steel frame is bonded and powder-coated.

The architect uses every possible aspect of the house to conform to the needs of comfort and efficiency, including the quirky exterior design. The structure's different layers, called modules, are alternately rotated to provide inhabitants shade and decks.

If you're worried about feeling secure in the zeroHouse, rest your head. Not only is there a fully-mortised locking system, but doors incorporate Kevlar material (a material five times stronger than steel by weight) and the windows have SentryGlas, which lends impact resistance.

Specht conceived this project specifically for people who want to reduce their ecological footprint and who have the money to spend on that goal. For instance, the structure can serve as a guest house or as a weekend getaway for the wealthy. The initial price is estimated at about $350,000, which, at a total size of only 650 square feet, places it at $530 per square foot. Specht hopes, however, that demand will soon increase supply, driving down the costs of prefabrication [source: Livingston].

The architect hopes to have the first zeroHouses built by the end of 2008 [source: Livingston]. How will this house run without the aid of power lines? Read the next page to find out.

Perhaps the most amazing thing about the zeroHouse design is that it relies solely on solar energy to run all its necessary functions. It harnesses the energy of sunlight with photovoltaic (PV) arrays and solar hot water panels mounted on top of the house. These arrays and panels incorporate solar cells, much like those on a solar-powered calculator. Sunlight comes down to earth in capsules -- what scientists call photons. These photons contain energy, and it's the job of solar cells to convert that energy into usable electricity.

When photons hit the semiconductor material of solar cells, the energy of the photons breaks electrons from their atoms. This creates a flow of electrons, or an electric current. The PV array system on top of the zeroHouse can use this electric current as electricity for whatever power needs the inhabitants have -- such as the built-in TV and refrigerator. The house need not rely on power plants that use fossil fuels and emit greenhouse gases to produce energy. Incidentally, this solar power also makes the house perfectly suited for remote geographic locations where there are no power lines. The architect touts the PV arrays on the zeroHouse as incredibly durable. They don't lose efficiency even after heavy use.

Because the house relies on sunlight for its energy, you might be wondering what happens when the sun is not shining. Why don't the TV and the refrigerator shut off at night or even on a cloudy day? Batteries can store a certain amount of the solar energy so that the zeroHouse has enough power to run even without the bright sun. The architect claims that the house saves enough solar energy after being fully charged to run for up to a week without sun.

Despite the fact that the PV panels can produce adequate energy, it's still important to keep the house's energy consumption low. To conserve energy, the architects have incorporated several features into the design, not the least of which is the insulation. We'll discuss those features on the next page.

The zeroHouse design attains virtually every goal of green technology by functioning completely off the grid. However, this would be impossible if it weren't for proper insulation. Because of the prefabricated nature of the house, the design needs to be usable in various kinds of weather -- both hot and cold climates. Although the house incorporates highly efficient heating and air conditioning systems, insulation allows those systems to work as little as possible by stopping heat from invading during hot weather and from escaping during cold weather.

Structural insulation consists of closed-cell foam, which, unlike open-cell foam, prevents the flow of vapor in addition to heat. This insulation achieves a thermal resistance rating of R-58 for walls, roof and floor. The thermal resistance rating indicates how well a material stops heat flow. The zeroHouse's insulation rating is impressively high, especially if you compare it to the standard recommended wall insulation ratings that range from about R-11 to R-28 in the U.S. [source: EERE].

Each room has full-wall windows, so it's pretty important that those windows resist heat flow. These full-wall windows are triple-insulated and use low-e heat-mirror glass. "Low-e" refers to low-emissivity and means that the glass incorporates a layer of metallic oxide, which hampers heat transfer. Heat-mirror glass reflects invisible heat without reflecting too much light.

Accounting for every nook-and-cranny, the architect uses high-quality insulation for the doors, as well. The doors are insulated with vacuum-sealed aero-gel panels. Aero-gel is a substance NASA made from the same materials as glass. However aero-gel is far less dense than glass -- in fact, it's the lightest solid on earth [source: Stenger], and it's a very efficient insulation material.

Because of this insulation, the house is suitable in a wide range of climates. The architect claims the house is suitable at latitudes 36 N to 36 S, at any time of the year. However, during the appropriate seasons, you could occupy the house comfortably in latitudes 47 N to 47 S.

The house's plumbing system also is efficient, relying on a force that is available at any time of day, is universally accessible, renewable and incredibly cheap (in fact, it's free). Read about this energy source on the next page.

In addition to its power system and insulation material, the zeroHouse's design also incorporates green technology for both its water consumption and its waste output. In keeping with the mission of resource conservation and location versatility, the zeroHouse has a cistern on its roof to collect rainwater. The cistern is able to hold up to 22,000 gallons of water. This way, without a connection to a water source, the house can collect and save water for use. The system even includes two filtering mechanisms that work to clean the water and make it drinkable. Another water conservation tool the house incorporates is a low-flush toilet. These kinds of toilets use less water to perform the same flushing functions as traditional toilets.

The plumbing system relies on the forces of gravity to keep the water flowing in the house. As an accessible and free source of energy, gravity is an ideal "green" power source. The force of gravity drives the water through low pressure water fixtures to provide the house with water [source: West]. Using gravity allows the house to avoid using electricity to power water pumps.

The zeroHouse is resourceful with its trash as well. The U.S. throws away over 200 million tons of solid waste every year, and over half ends up in landfills [source: EPA]. Green technology attempts to provide new ways to keep the environment clean by reducing our waste. In this vein, the designers of the zeroHouse believe that trash is a terrible thing to waste. So, they incorporated a compost unit underneath the zeroHouse to collect waste.

Compost units break down organic waste into usable fertilizer. Like all compost units, the one under zeroHouse works by harnessing the natural processes of bacteria by exposing this waste to the proper amounts of soil, water, and oxygen. The soil contributes microorganisms, which are the mechanisms that drive the process. Microorganisms, which include bacteria, feast on the trash in the pile, which effectively breaks down the material. Water and oxygen need to be part of the equation to help the microorganisms thrive and do their work.

The compost unit under the zeroHouse converts organic waste into fertilizer. The architect claims that, under normal usage, this unit need only be emptied twice a year.

This house is not just efficient, it's smart. Learn about the house's brain and its bone structure on the next page.

One system in particular helps to keep the owner in control of the different features of the house. The architect calls this the "house brain," and it makes the entire house automated. Using special sensors mounted around the house, the house brain can keep track of activities. The brain regulates the power usage in the house. It even has a hibernation status to maintain the house when it's not in use. The system is web-based, so inhabitants can keep an eye on this system via their computer.

The zeroHouse has a light touch, and not just because of its virtually nonexistent ecological footprint. The house's foundational system literally has minimal impact on the ground where the house sits. The four helical anchors keep the foundation solid while not disrupting the landscape. The architect orchestrated the foundational system this way so that the structure touches the ground at only these four points. This makes the house well suited for sites where more disruptive construction is difficult or not allowed.

Though these anchors have only a slight impact on the earth, it will take more than the huff and puff to blow the zeroHouse down. The anchor system, in conjunction with the tubular steel frame of the house, allows the house sustain up to 140 miles per hour (225 kilometers per hour) winds. In fact, the structure of the anchors supposedly allows the house to sit safely on a slope of up to 35 degrees or even in up to 10 feet of water.

The zeroHouse makes living off the grid seem like a plausible reality. However, skeptics point out that green technology remains highly expensive and is therefore not tenable on a wide scale. But, for those concerned about global warming, the possibility of living without a dependence on energy that results in the release greenhouse gases is tantalizing. Time will tell whether the zeroHouse can stand up to rough environments, the dwellers' energy demands and the critics.

Take a look at the links on the next page to learn about other green buildings and sustainable technology.