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Passive Solar Addition Keeps Home Warm and Cool Naturally

The guiding principle of this three-story home addition project is its passive solar design.   Passive solar follows one of the first and most simple rules of sustainable design and green building.  That is to orient windows and walls to take advantage of the natural lighting, heating and cooling effects of the building site.


passive solar designed two story addition Deep overhangs protect the interior from heat gain in summer


This passive solar addition emerges dramatically from the existing house on an angle that follows the sun to maximize solar exposure.  In winter, when the sun is low on the horizon, “free” solar heat radiates through the many large south-facing windows on all three levels.  A dark slate floor on the main level absorbs that heat all day then releases it at night.


stone floor of passisve solar addition stores heat The natural stone floor is a thermal mass. It absorbs solar heat during short winter days then radiates it out during the long night


In summer when the sun is higher on the horizon, carefully calibrated roof overhangs shade windows helping to keep it cool inside.  These built in energy-efficiency measures significantly reduce the need for electricity consumption.


passive solar addition interior - kitchen

Benefits of Sustainable Design

This addition nearly doubled the size of the home.  By reconfiguring existing space, we were able to introduce a room to room flow and logic that was not present in the original.

passive solar addition interior detailThe clients increasingly embraced our commitment to sustainable, environmentally sound design and construction as its many advantages unfolded for them.  Homeowner William Flint said, “I didn’t seek out the green to begin with, but I found the designer and he brought the green along with him and I’m glad he did.”

This tends to be the case with our commitment to sustainable design.  Whether or not our clients start out with the intention of building green, their experience with it during the design and building phases wins them over.

What Makes This Home Addition Green

The owner’s willingness to experiment with new approaches allowed us to employ numerous green building concepts and materials.

During the course of the project, the entire electrical and plumbing systems were overhauled.  Every cable and pipe was replaced and new water service was installed. We used the most sophisticated and efficient heating and air conditioning equipment available.


passive solar addition 2nd floor interior room The second floor sitting room

Envelope: Exterior & Insulation

  • Strategically placed sun tunnels drop natural light into the center of the house reducing the need artificial lighting during daylight hours.
  • Walls and roof are insulated with Icynene—a foam material sprayed directly into the framing cavities. Foam, unlike conventional fiberglass batts, fills every void in the framing.  This prevents air infiltration and precludes mold growth.
  • Exterior walls are meticulously flashed and rain-screened to prevent moisture intrusion.
  • Energy Star™ rated, white-colored roofing materials reduce cooling loads and mitigate the urban heat island effect
  • Both existing and new attics are completely insulated, thereby creating consistent systems-wide efficiency.
  • All new windows are made of fiberglass (stronger and more stable than vinyl) and feature beautiful, clear pine interior surfaces.
  • All existing windows were replaced with the same fiberglass windows.
parallam beams

Parallam beams

Structural Support and Materials

  • The ceiling is framed using a system of exposed Parallam™ beams. These beautiful, extremely strong beams are made from wood fiber harvested from branches or trees too small for use as conventional lumber
  • Underlayment for the second floor is composed of Dow Woodstalk, rigid panels.  This product is manufactured from wheat straw—an agricultural waste product.

Systems & Appliances

  • The Energy Star HVAC equipment features multi-stage units controlled by humidistats and thermostats to provide the twin benefits of efficiency and comfort.
  • Appliances in this home, including ceiling fans, are Energy Star™ rated.

Our clients continue to enjoy the benefits of our multiple energy-saving measures.  By saving energy they save money every month and every year.  However, that savings is secondary when compared to the immensely improved quality of life the owners now enjoy in their green remodeled home.