Thomas Eco House / Designs Northwest Architects
The Thomas Eco-House is located on an 11-acre site in the Cascade foothills between Arlington and Sedro Woolly. The house sits atop a hill bordering forest land and has territorial views of the surrounding wooded hills as well as views of Mount Rainier and the city of Everett to the south. The house has four stories, which allowed for more living space while maintaining a relatively small footprint and also better taking advantage of the views from the site. The site is landscaped with native vegetation which is irrigated during the dry summer months with roof runoff which is stored in a cistern.
The client showed an early interest in energy efficiency and sustainable low maintenance design. These goals guided the entire design process. The house uses Insulated Concrete Form Construction (ICF) which consists of two layers of rigidly shaped insulation between which concrete is poured. The insulation stays in place inside and out creating a highly efficient and airtight wall system. ICF construction results in a 44% reduction in heating energy required and 33% reduction in cooling energy required compared to an equal-sized wood-frame house. ICF also allows easy application of stucco directly to exterior insulation. This provides a durable, low maintenance finish.
To improve heating and cooling efficiency, the house uses a geothermal heat pump connected to a hydronic heating system. The system uses air from an underground chamber which uses the insulating properties of the earth to provide a more stable temperature for the operation of the heat pump. A geothermal heat pump can be up to 45% more efficient than a traditional heat pump that uses ambient air. The heat pump is connected to a high efficiency boiler which supplies heated water through a piping system embedded in the concrete floor. This hydronic heating system consumes approximately 30% less energy than an equivalent forced air system. The house is also wired for solar panels and/or wind power although these have not been installed at this time due to budget constraints.
The house was also designed to take advantage of passive solar principles. A large bank of windows on the southern exposure allows the sun to penetrate inside. Concrete floors act as a thermal mass that stores heat gain during the day and slowly releases it throughout the evening, allowing for drastic temperature swings. On particularly hot days there are motorized sun blinds which can be lowered to keep the sun out of the interior spaces. The staircase was also designed to provide natural ventilation through a solar chimney effect. The “bubble” at the top of the stairs has operable windows which, when opened, create a natural convection effect drawing warm air up the stairs and out of the house.
The Thomas Eco-House is divided by function between floors. The ground floor is occupied by a general living space including the kitchen, dining room and living room. The floor plan on this level is open with floor to ceiling windows opening to the view. The upper floor contains the sleeping areas and a reading loft that opens to the living room below. A fire hydrant provides a unique visual and physical connection between the two spaces. The stair tower continues upwards to a special viewing area dubbed the “Bubble”. This area contains glass walls and ceilings that take full advantage of the expansive views and night sky. A roof terrace is accessible from the bubble. The lower floor is a daylight level which has been fitted out so that it can be used as a guest accommodation or as a mother-in-law’s apartment. All four floors have polished concrete floors that add to the home’s no-frills aesthetic. The forms of the building are simple and follow the layout of the interior spaces reinforcing the overall strategy of efficiency that has been the driving force behind the design.