The Donnelly house is organized along a rectilinear volume that separates the private realm of the dwelling from the public. This volume creates a spine along the east-west axis and houses constituent elements such as the heating and cooling ducts, primary electrical raceways, boiler, water heater, piping, etc. The spine also provides a heavy mass in which solar energy is stored as well as reflecting natural light deep into the interiors. The spine is also the core of the house. The interior of the core is finished with a traditional diamond plaster and hand rubbed with bee’s wax. This provides a neutral area on which the owners’ art collection is displayed.

A passive cooling system is employed by using dark obsidian rocks in a shallow fountain to create a natural evaporative flow that enters the house through the lower quarters and is exhausted through the highest (warmest) point in the house at the top of the open stair tower. The main spaces have simple openings that allow the cooler prevailing breezes to pass from room to room during the warmest months. Horizontal openings are kept to a minimum and deep overhangs limit the amount of solar gain during the summer.

As the sun begins to travel lower in the sky in the winter months, the rooms are flooded with natural light because of the calculated depth of the roof overhangs. Along the south face of the house, a network of integrated trombe walls store heat during the winter days and radiate that heat slowly into the interior spaces throughout the nights.