The winter sun heats the house through the large south-facing windows. Photo By Heidi Marttila-Losure
Incorporating passive design principles in new house construction means a comfy house and lower heating bills
By Heidi Marttila-Losure
- Green Spark 1: Use Passive Solar. 
- Green Spark 2: Recycle What You Can. 
- Green Spark 3: Recycle Creatively. 
- Green Spark 4: Consider Powering Your Business with the Sun. 
- Green Spark 5: Upcycle. 
- Green Spark 6: Go Geothermal. 
- Green Spark 7: Find Common Ground on Net Metering. 
- Green Spark 8: Get an Energy Audit. 
- Green Spark 9: Recycle and Make Money for Your Community. 
- Green Spark 10: Use Reusable Bags. 
- Green Spark 11: Encourage New Mothers to Breastfeed. 
- Green Spark 12: Make Sleeping Mats From Plastic Bags to Help the Environment and Others. 
One interesting feature of our house-made-from-a-granary is what you don’t hear on sunny winter days: Neither the wood stove nor our backup space heater has to make a sound.
We designed our house using passive solar principles, which allows the heat from the sun to heat the house.
The four basics of passive solar design are:
- Large windows on the south side of the house, limited windows on the west and east sides, and few to no windows on the north side.
- A properly sized overhang above the south windows, so light comes in in the winter but the windows are shaded in the summer.
- Adequate thermal mass in the house, which can absorb heat during the day and give it off at night.
- Adequate insulation to keep heat in.
Many people tried passive solar designs in the 1970s and ’80s but didn’t get all four pieces of the puzzle in place—if the overhang isn’t right, for example, rooms are likely to get too hot in the summertime.
Our design isn’t perfect, either. Since we were working from a building already in place, there was only so much engineering of the overhang we could do, so we get some August sun. (Curtains help with that problem.) And there was a limit to how much thermal mass we could creatively fit into the house.
But it’s good enough for us! Having a warm and cozy house in the winter was well worth the added time it took to design it. And since we were able to incorporate the design principles early in the building process, the additional cost was minimal. In fact, I would recommend that all new houses in our part of the world incorporate passive design principles for more energy-efficient, comfortable homes.
If you are interested in passive solar design, here are some resources to help you get started:
- Basic passive solar overview, including codes and standards: www.wbdg.org/resources/psheating.php 
- Sustainable by Design calculators: susdesign.com/tools.php 
- “The Passive Solar House”  by James Kachadorian. New version from 2006 includes a CD-ROM with custom design software.