1250 SQ. FT. (Arrow)



1. This plan was developed to address the problem of thermal mass in a passive solar house. Of the five elements that make up a passive solar house;
a. Superinsulation,
b. Air sealing,
c. South facing glass,
d. Thermal mass, and
e. Ventilation.
The most problematic (to me) is providing enough thermall mass in direct sunlight for adequate heat storage, in a way that does not overheat the air, and does not negatively impact on the livability of the house.

2. In this plan, as usual, the exterior walls on the north, east and west are straw bale for insulation, and the south wall is mainly glass, but the interior walls are heavy cob or cob covered straw bale angled to accept direct sunlight through most of a winter solar day (10:00 am to 2:00 pm), without interfering with the livability of the house. As the winter sun rises in the Northeast, it warms the tile floors and the air in the house. By noon the sun contacts the dark colored thermal mass walls at about a 45 degree angle, and more heat is stored in the mass and less in the air. By early afternoon, the sun contacts the mass at nearly a right angle with most of the heat stored directly in the mass without interfereing with other activities of the household.

3. As usual, it is not a perfect system, as some of the direct sun will find its way into areas in the living and dining rooms where it is not appreciated. To supplement the (angled) mass wall system consider adding movable storage "walls" that can be adjusted as needed to store additional heat and even out the temperature cycle. A bank of large fish tanks in a roller frame, could be moved in the entry way to accept direct sun as needed, act as a shield and store substantial quantities of solar heat. Note the fireplace is placed to store solar heat, shield and protect the living area.

4. Asside from the thermal properties, this is a neat house, the only in this series (exception, earthship), that has thick straw or cob inside walls. The angular walls creates interesting and unusual spaces and relationships that work remarkable well. This is a "sophisticated" plan, a "modern" plan, great for the couple that wants to make a statement...in a modest, conservative (energy) way.

5. In terms of "features", the triangular master bedroom has direct access to the triangular bath. The living area is centered and protected with build in seating and equal access to the "entertainment center" and the fireplace. The "L" shaped kitchen is efficent and just the right size with an island and a pleasant, perfectly shaped dining area with walk out patio. The extra room can be bedroom, office, studio, or workroom.

6. Some of you will notice the lack of a furnace room. Add an attached unheated (but well insulated) mudroom, airlock, shed out the back door to include the hot water heater and boiler. Note the stacked washer, dryer in the bathroom. This works fine, but if you like, put them in the mud room. This airlock, if designed properly, will allow you to add a bedroom, or studio to the north (with solar access) using the airlock as a passage way and entrance.

7. This plan was originally designed with the arrow facing east, but reversed here to put the bedroom on the east (to accept morning sun), and to allow the kitchen/dining area to recieve the first rays of winter sun. Also to place the thermal mass walls in direct sun on winter afternoons. It works the other way also but with diferent performance characteristics.


(please type your comments here...and include your e-mail)

Webmaster and Straw Bale Design, Robert Andrews, 3223 Urban St., Pueblo, Colorado 81005
(719) 561-8020 (719) 546-0315