Passive Solar Site Design Planning

Passive solar site design must take the sun’s path into account and its interaction with the house throughout the seasons.

In the planning stages for a passive solar retrofit project, I took pictures of the sun’s path on the summer and winter solstices to learn more about how the sun interacts with the house. Both photos are of the sun through the same window, but in different seasons.

These site specific solar attributes help in the design of a more efficient passive solar retrofit.  This is what I’ve learned for this particular project.

Summer Solstice

In the summer, the sun enters the house through the front windows for only a couple of feet. Here’s how the sun potentially impacts the different sides of the house.

East Side – 6:40am – 1:00pm – 5.5 hours of solar heat energy (direct sunlight)

Southern Front of House – 7:00am to 2:30pm – 7.5 hours of sunlight

Western Side – 1:0opm to 7:30pm – 6.5 hours of direct sun (strong)

Winter Solstice

[singlepic id=7 w=320 h=240 float=right]In the winter, the sun enters the house through the same front windows and extends deep into the house, for about 20 feet.

East Side – No sun

Southern Front of House – 9:00am to 3:00pm – 6 hours of direct solar heat energy

Western Side – 11:00am to 2:53pm – 4 hours of partial sun

Both the summer and winter solar paths will be taken into account so that the house will be constructed in a manner that allows it to naturally (passively) be warm in the winter and cool in the summer. This will hopefully be accomplished with the design, orientation and materials of the house working together.

Here are links to Passive Solar Building Principles, a diagram of the Sun’s Movement and to amazing solstice pictures throughout a whole year with a pinhole camera.

Based on the observations this is what I will try:

The passive solar window wall will be located on the southern side, with a poured cement floor. This will allow the winter sun to hit the sandstone rock wall and transfer the heat around the house.

The western side of the house receives minimal winter solar heat gain, but gets pounded by it in the summer. It should have an overhang that keeps the hot afternoon sun from entering the house or hitting the stone wall. There should be some windows to allow light into the house, but they should be placed in a manner to afford privacy from the neighbors while allowing the maximum amount of natural light into the house.

Now it’s a matter of designing the house / researching and getting the materials / meeting with the engineer / getting the variance / applying for the building permit…    (Oh my. – 11/2010 – This project was stopped because the house was sold and I moved away.  But I learned a lot about passive solar building!)