The southeast-northwest plan configuration places larger wall openings facing south and smaller wall openings facing north, taking advantage of solar gain and minimizing heat loss in cold weather months. Warm weather shading of south-facing openings is provided by two large locust trees and interior draperies.
A frost-protected shallow-foundation design with 3-inch thick EPS foam layer and vapor barrier covers the entire building footprint. In winter months, some daytime solar gain through south facing glass is stored in the 5-inch thick floor slab for nighttime radiant heat.
R40 wall and R50 roof thermal resistance is achieved using structural insulated panels. Tapered foam roof insulation provides additional thermal performance.
Heating and cooling is provided by a geothermal heat pump system with forced air distribution. Primary cold month heating is provided by a gas-fired boiler and in-slab hydronic heating coils. An energy recovery ventilator provides fresh air and humidity control in winter months.
Challenges: A high water table is accommodated by a 24-inch deep frost-protected shallow foundation with continuous, sealed below foundation vapor barrier and insulation layer. The bottom of the foundation system after final grading is approximately 3-1/2 feet above the water table at its highest level.
Considerations: Roof and ground surface storm water control is accommodated by two separate systems: (1) roof downspouts to solid underground pipe to rain garden by gravity and (2) underground perforated footing drains to solid pipe to rain garden by gravity.
Unique or innovative Solutions: (1) Geothermal heat pump heating & cooling with in-floor radiant heating; (2) rain screen wall assembly with 6-1/2” R40 SIP wall and exterior surface of corrugated, concealed fastener aluminum panels with a high-performance paint coating; (3) low slope roof assembly with 8-1/2” R50 SIP roof, tapered foam insulation and fully-adhered EPDM roofing membrane.
Lessons Learned: Lack of overhang at porch allows wind driven rain to spatter through screen material. This problem will be eliminated by the addition of a shallow, sloping metal awning on three side of porch to protect the face of screen and storm panels.
Sustainability: (1) Geothermal heat pump with circulation through three 250-foot deep wells; (2) high thermal performance wall and roof assembly with continuous vapor barrier on all 6 sides of structure; and (3) an energy recovery ventilator providing a constant flow of tempered fresh air and, in winter, humidity control for a tightly sealed dwelling.
SMNG A Ltd.