A building's envelope is arguably the most important consideration when designing a sustainable structure. Taking cues from the Passive House standard, the walls for the Commons will be made using double steel stud construction techniques (with an overall thickness of 12"), insulated with AirKrete and clad in fiber cement paneling. Currently AirKrete does not have ICC approval, but we're hoping that BDS will let us use it anyway because it is, non-toxic, not a petroleum product (as most other high performance insulations are) and not susceptible to moisture damage. Fiber-cement cladding is a highly-durable and non-toxic material that will act as an effective barrier for the insulation from the elements.

Large glass roll-up doors on both the greenhouse and sunspace will blur the boundary between indoors and out.

A subterranean shop will allow the occupants to maintain backyard space for a garden and fruit trees. By virtue of being underground sound created from tools and activities will be deadened reducing noise pollution.

The courtyard provides a transition between the home and backyard as well as a buffer between the two master bedrooms.

All power used in the home will be provided by a roof mounted solar array. This system will be grid inter-tied, obviating the need for batteries. Through the course of the year, the home will be net-zero energy; when the solar array is producing more energy than is needed it goes to the grid, when the solar array is not producing enough, the home pulls power from the grid.

Incorporated in the roof design is a green roof, which will reduce the urban heat island effect and potentially temper heating and cooling loads in the building. The green roof will also slow storm water runoff removing the load on the city's waste-water system. If everyone were to do this, along with catchment, it may have relieved the need for the Big Pipe Project.

All water used in the house, including potable, will be gathered from rainwater falling on the roof and stored in a cistern. This not only removes the reliance on municipal water systems but also increases awareness of usage.

This portion of the roof is transparent to allow light to filter through, but keeps the courtyard below mostly dry and allow for its use during rainy Portland weather.

The windows in the structure will be chosen depending on orientation to the sun - all will have a high R-value, but in some cases R-value will be traded for a higher Solar Heat Gain Coefficient (SHGC) allowing for a greater harvest of the suns energy. Daylighting was also a priority in design; all living spaces will have at least two walls with windows in order to balance the light.

A energy recovery ventilator (ERV) allows for an airtight house; this provides energy efficiency because the stale outgoing air is passed through a heat exchanger, where the outgoing air exchanges its conditioned state (hot or cold) with the incoming fresh air, conserving energy. ERVs also allow for humidity levels to be monitored and controlled.

We like them, need we say more? (They also hide the conduit for the photovoltaic system, solar hot water tubes and rainwater conveyance.)

This space will have a multitude of capacities, ranging from an entertainment space (for movies and music) to an art space (music creation, writing, painting) to a guest bedroom.

We've chosen to use waterless composting toilets thereby lowering overall water requirements for the house. A custom bidet will be installed on the toilet to obviate the need for toilet paper (a tree by-product, which during its creation uses far more water than a bidet would). By using a composting system we are able to extricate ourselves from the municipal sewer system (shower and sink water may still go to the sewer, as greywater processing is currently illegal in Oregon (we're trying to change this), but we will rough plumb the infrastructure in order to implement a greywater reuse system when it becomes legal). By removing our toilets from the municipal sewer system we lessen the load on the system, which, during times of high rainfall, can overflow into the Willamette River, due to the combination of stormwater and sewer water. Composting toilets also allow for an examination of the notion of "waste"; instead of being classified as a waste product the compost will be used as fertilizer for the ornamental landscaping around the house.

Many components within the house, including the interior walls, will be constructed from reused materials such as wood and glass from the previous building.

Earthen floors have been specified for all the rooms, with the exception of the kitchen and bedrooms. Earthen floors have little to no embodied energy, are made from local materials and are pleasant and warm underfoot (they are, structurally, very similar to concrete).

The house is designed with two master bedrooms in order to increase density and accommodate two families. This increased density fosters community, mutual aid and allows the sharing of resources which lowers the overall impact of all involved.

An indoor greenhouse will allow the occupants to supplement their diet with fresh, home-grown foods. The plants will condition the air by removing pollutants that enter the house from outside and from off-gassing electronics. Plants have also been shown to increase the productivity and happiness of occupants. In addition to offering a place to grow plants the greenhouse will also have a large quantity of glass to capture solar heat gain from the sun, which can then be drawn into the living spaces.

Like the greenhouse, the sunspace will capture solar heat and store it in the thermal mass of the earthen floors. The sunspace will also act as a flex-space with its roll-up glass doors allowing it, in milder times of the year, to bridge the gap between the kitchen and the outdoors. We imagine the room to function as a place to eat, lounge and create.

High traffic areas and circulation paths will be made of an earth based "concrete" because of its durability. Areas where the occupants spend more time standing will be clad in reused wood (from the previous house) to be warmer and more comfortable underfoot.

Most refrigerators currently available are inefficient for two reasons: they're poorly insulated and open via a swinging door, thus allowing the cold air to literally "fall out." Like the building envelope the refrigerator we've designed will be super-insulated. We will insulate the refrigerator with a new vacuum insulation - allowing R-50 in two inches. Access to the refrigerator will be through drawers, allowing for easier perusal and removal of the contents - also reducing the amount of time that the drawers stay open.

A washing machine that spins most of the water out and in conjunction with a clothes line, will eliminate the need for a clothes drier.

A built in central vacuum cleaner will result in cleaner air, exhausting dust and particulates to the exterior.

The two successive doors at the main entrance will function as an airlock, a room separating indoor and outdoor space and helping to prevent conditioned, interior air from mixing with exterior air. Shoes will be removed in the airlock thereby sequestering incoming dirt (lowering household dust). The airlock will also act as a visual transition from the outdoors to the indoor space.