A LEED Platinum home fits into a historic neighborhood
All photos copyright Tim Ridley.
Carl Seville, a principal at SK Collaborative, has decades of experience in green building and construction, and he put them to use in building a new LEED home for himself and his wife. The Craftsman-style home in Decatur, Georgia, also ended up becoming the winner of the 2017 LEED Homes Award for Outstanding Single-Family Project.
Balancing building goals
Working with architect Thomas Hood, Seville navigated strict requirements from the local historic commission on square footage, accessory buildings, permeable pavement and tree canopy preservation, while also building a home to LEED Platinum standards. He chronicled the process of making renovations to a home in an area with both green building certification and historic commission requirements in his frank and humorous blog series, Green Building Curmudgeon.
The city of Decatur has a green building certification ordinance, and Seville selected LEED v4 from among the locally accepted options, in part to gain experience in the more rigorous new version of LEED before applying it to future client projects.
The house is in a neighborhood full of historic homes, many over a hundred years old. An unusual aspect of this project, among others Seville has worked on, is that although it is a very traditional house, "almost indistinguishable" from the homes around it, it is still high-performance. "The house filled a gap in a block of historic homes, and did it so well that most observers are not aware that it is a new house. I have even driven past it myself a few times even though I live there," says Seville.
Achieving Rainwater credits
The most challenging LEED credit to achieve, for Seville, was Rainwater Management, but he was ultimately able to achieve the maximum 3 points through the use of pervious paving materials, planted areas and impervious surfaces that were directed to on-site infiltration.
For example, the entire driveway is pervious concrete, and the parking pad in front of the carport is made up of loose-laid pervious pavers. Both areas were installed over a 9-inch layer of gravel, which was placed on top of a geotextile fabric to keep mud out of the gravel bed. The impervious areas directed to infiltration areas comprise half of the roof area of the house and the entire carport. Seville directed the downspouts from these areas to a large dry well in the backyard.
The total permeable area and impermeable area drained to infiltration features make up 86.64 percent of the entire site.
"I elected to use the pervious paving materials to achieve points toward certification and to meet the city lot coverage requirements," explains Seville. "The dry well for infiltration was not required for lot coverage; however, I elected to include this to avoid any excessive erosion or stormwater runoff from the roofs."
Setting up for good indoor air quality
As occupants, the Sevilles find that the interior is always comfortable, using minimal HVAC. The ductless HVAC "was a bit of a risk in a house this size," says Seville, "but the extremely tight building envelope and relatively open floor plan allowed me to condition the entire 2,646 square feet with no ductwork."
The structure retains heat well in cold weather and manages heat and humidity very well in hot weather. "In moderate weather, the house is often cooler than outside, so we often open the windows instead of turning on the heat in bridge seasons," says Seville. He experiences the house as being very quiet and having excellent indoor air quality, with minimal dust and dirt.
Carl Seville's number one piece of advice for someone seeking to build a home to LEED standards: "Start the design with sustainability and certification in mind. Don’t try to layer it on a completed design. If you think green from the start, it is not hard to build better, at little (if any) extra cost, and if truly effective, you can reduce costs while improving performance and sustainability."