Kirsch Center

Kristin Sullivan - Environmental Studies

Sullivan's Solar Straw Bale Home Article

Capitola, CA - October 22, 2001 -  Straw bale architecture is gaining popularity in Santa Cruz County as Mark and Kristin Sullivan begin construction on the first straw bale home in Capitola. The home was designed to provide passive solar benefits that will take full advantage of the sun for heating and cooling. Baled rice straw, which has superior insulative properties, will be used for the majority of the walls further minimizing the energy required for heating and cooling the home. The home will also feature a solar water system for heating water and a photovoltaic system that will provide electricity.

The home is being built with sustainability in mind, and building materials include reused, recycled, and sustainably harvested wood, high fly ash-content concrete, earth and lime plasters, and of course, straw bales. Mark and Kristin developed the final design with architect Kelly Lerner of One World Design in El Cerrito, and builder Michele Landegger of Boa Constructor in Watsonville.

The Sullivans first conceived the construction of this home thirteen years ago when Kristin took a solar design class at San Jose State University. Since that time, Kristin and Mark graduated from SJSU with environmental degrees and have been working in environmental fields; Kristin is an environmental studies teacher at De Anza College in Cupertino, and Mark is an environmental consultant for RRM in Santa Cruz.

While details regarding the home's design have evolved over the years, the guiding principles have not changed. The Sullivans dreamed of a smaller house in an urban setting that used basic passive solar techniques, which allows the sun to heat the house. The 1,450 square foot home will be located near Capitola Village. Passive solar techniques include proper orientation for maximum southern exposure, liberal glazing on the south side of the home to take maximum solar advantage when the sun is low during the winter months, and high thermal mass in the form of the concrete slab to store solar heat in the daytime for nighttime use.

To maintain temperature within the home, the Sullivans are using rice straw bales on the north, east, and west walls; straw has superior insulative qualities. Rice straw is an agricultural waste product that is left over after rice is cultivated. In California, rice is grown predominantly in the Sacramento Valley, and in the past, rice straw was burned after the harvest. In the fall, you could see plumes of smoke rising from these fields for miles. In recent years, the burning of rice straw has been phased out due to air quality concerns, and the rice farmers have been left with the task of finding markets for this stubble. Straw has a low nutritional value, so it is not viable for feed and the shear volume of straw makes it undesirable to till under.

Straw bale construction provides an excellent outlet for this waste straw. Standard 6-inch thick fiberglass batts have an R-value of 19, straw bales have an R-value close to 50. Another advantage of straw bale construction is that the use of wood is minimized; Ms Lerner estimated that the wood required to build this straw bale home is approximately 40 percent less than a conventional home of this size.

The primary heating system for the home will be the sun. A backup hydronic heating system has been installed in the concrete slab, but it is likely that this system will be used infrequently, only when several days of cloud cover block El Sol. For the summer heat (which is not too extreme in Capitola), the house was designed to hide from the sun. The eaves will shade the house in the summer due to the higher arc of the sun's path. Additionally, the home design includes a trellis on the south side of the home that will support deciduous kiwi fruit vines. The kiwi vines will provide shade in the summer, but will allow the light to pass through in the winter.


For further information, contact Kristin or Mark Sullivan at 831-477-0571.


Last Updated: 9/8/09