Sustainable Structures of Texas

Date ant Time:  August 6, 2011  8:00 am

Presenter:  Lee N. Hall, P.E., LEED AP

                  President

                  Sustainable Structures

Lee gave us a tour this morning of his ‘TERRAcourt Home’, in the Montgomery Farm Development,  which is the first LEED Gold certified home in Collin County with an impressive HERS index of 49 (Energy Star requirement is 85) and a tightness coefficient of .08 (76% higher than industry norm).  It also received the EPA’s Indoor airPlus designation.  Lee mentioned that he can guarantee an average monthly electrical energy cost of $102/month for the home.  The home was completed in 2011, is over 5000 square feet and was estimated to cost approximately $215 per square foot to build.  The home is currently on the market with an asking price of $2.5 Million.

TERRAcourt Home

With an interest in using ‘off the shelf’ technology when building the home, Lee opted to use ‘Advanced Framing Techniques’.  The wall construction includes 2x6 studs at 24 inches on center in lieu of standard construction which is 2x4 studs at 16 inches on center.  This cuts ‘thermal bypass’ which is heat transfer through the wood studs and also increases the depth of insulation that can be accommodated in the wall.

wall construction

Some of the sustainable features of the home include:

• Standing seam roof with seams rolled together.  (This roof is properly oriented with what looks like an acceptable slope and is ready to received a photovoltaic system with a mounting system that can be easily attached to the standing seams)
• The use of low VOC paints and adhesives
• Rainwater capture system that collects rainwater in a 2000 gallon bioswale rain garden. (see photo)

bioswale

• A whole house ventilation system
• Stone facade
• Wall insulation value of 19.4 plus 5 for sheathing.
• Foam attic insulation.
• LED lighting (exterior and interior – 75% of lighting)
• Window U factor of .32
• Fan in garage turns on automatically to expel vapors.
• Exhaust fan in bathroom uses humidity sensor to turn on. (can be bypassed)
• Water temperature can be set in bathroom for shower.
• Native grass (Buffalo Grass), plants and rescued trees from earlier on-site and off-site development.

Some features of the home which could have been done differently to improve its energy performance:

• The ‘eyebrows’ over the windows could have been re-designed to actually shield the windows from direct sunlight.  A ‘shading study’ on the windows could have been done that would tell the designer the extent of shading required based on the orientation of the windows. (see McKinney Green Building)
• The house uses 3 – 3 ton Air Conditioning units with SEER’s of 16.5.  Currently there are units with SEER’s as high as 23 on the market.

window with 'eyebrow' shading

The  Montgomery Farm Development is focused on designs that are sustainable.  In the Master Plan (see below) they have included wide open spaces with greenways and trails that connect residents to schools, work, shopping and each other.  The patchwork of greenways includes protected meadows, woodland gardens and wildlife preserves.  In this development they have set aside 20 acres for a LEED pilot project with USGBC. They are part way through the approval process; however, they have a problem with the density factor for the development.  LEED-ND requires a density of 7 units per acre and an FAR (floor area ratio) of .5. The Stage 1 approval process for the development already cost over $30,000.  

Montgomery Farm Master Plan

Following are links to the websites:

http://ssotx.com/index.html

http://montgomeryfarm.com/