case studies
Climate-Conscious Building
DON NICHOLSON PHOTOS
Creating a Net-Zero Home with Low Embodied Energy BY DON NICHOLSON ecky and Noell Tin split their time between Asheville and Charlotte with work projects in both cities, and 16 North Belgium Lane in West Asheville was planned as their second home. After struggling to find a home within the existing Asheville stock that had the size and configuration they needed, they saw available land in the net-zero subdivision we are developing at Green Path Commons and were intrigued by our strong personal commitment to climate action. The Tins had been sympathetic to actions that curb climate change, but had not studied the topic in depth. Central to their decision to have us design a net-zero home for them were the climate concerns expressed by their children. They approached net-zero building as a grand adventure; their enthusiasm matched ours. They learned the nuances of the
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home’s envelope, thermal bridging, heat pumps, and the importance of a home’s basic energy efficiency relative to that of rooftop solar. We worked with them to design a small 850-square-foot house that flows seamlessly to the deck, yard, and adjoining community garden and pavilion. Their experience illustrates how important it is for builders to introduce their clients to the merits of energy-efficient homes and enlist them to spread the word. Our longstanding approach to energy efficiency — LED lights, ENERGY STAR®-certified appliances, mini splits with high SEER (seasonal energy efficiency ratio of 33) and HSPF (heat seasonal performance factor of 14), heat pump water heater, heat pump dryer, R-30 walls and R-65 ceiling — gave the project a Home Energy Rating System (HERS) Score without solar of 28. The solar photovoltaic (PV) system on the roof brings the HERS down to 1. The elements work to-
gether; the thermally tight envelope allowed us to use just two small single-head mini splits. This is possible because heat has time to diffuse from room to room before slowly dissipating through the walls and ceiling. A small PV array of 3.55kW is needed to power the home. We decided to support the house on helical piles instead of concrete footers. Helical piles are stout galvanized steel pipes with a twist of steel plate at the end (15-inch diameter). The pile is like a giant twist drill bit that can be screwed into the ground by a track hoe with a torque drive. They are often used for poor soils, such as fill dirt. Our soil is great soil, so why use helical piles? Concrete foundations contribute significantly to greenhouse gas; steel is less offensive. The end of life for a helical pile is to be unscrewed and reused or recycled. Helical piles affect the work site in a positive way. Even before finalizing the house plan, we graded
The view of 16 North Belgium Lane from the deck side.
then seeded the sloping lot to provide a building area. The process was clean, automatic and systematic. We had a nice area with U-brackets sticking up every eight feet, ready for girders, and no piles of dirt. The 700-square-foot deck looks towards the community garden. Our target was to integrate the home with this setting. We
Project Team Builder — Nicholson and Sun Helical Piles — Goliath Tech WNC Engineering — Engineering Support Services
Solar Contractor — C.M. Wilson Inc. Insulation — Pisgah Insulation HVAC Contractor — General Heating & Air Conditioning
HVAC Equipment — R. E. Michel Electrical — Crown Electric Heat Pump Water Heater — Victory Plumbing HERS Rater — Vandemusser Design
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