Solar Laminate Home Meets Passive Energy Requirements
Whirlwind Solar in conjunction with Corey Saft, an architecture professor at University of Louisiana at Lafayette, announced the first application of solar laminates on a certified "Passive House" home.
According to the company's press release, it is the first such home across the South and West Coast. Keihly Moore, with the Illinois-based Passive House Institute US that gives the certification, says Saft is the first in the South. The use of solar photovoltaics, along with the Passive House design criteria of 90 percent reduction in energy usage over traditional homes built to current codes, makes this an affordable zero-energy prototype for the extreme conditions in the hot and humid South.
Following the general Passive House strategy, the home is super-insulated and extremely well sealed, making the construction act more like a thermos to preserve the conditioned air inside and consequently requiring much less overall conditioning of air. The systems in the house are all standard and readily available but it is their integration into a whole house strategy that makes the final product efficient and unique. The primary system is based on a a small (1 ton) mini-split air-conditioning system and the Ultimate Air RecoupAerator Energy Recovery Ventilator (ERV). With 95 percent energy recovery, MERV 12 filtration, and dehumidification, the ERV is the black box in the system that makes it all possible. The house also uses an air-to-water heat pump to supplement cooling and dehumidification and provide hot water.
The wall assembly manages most of the thermal issues, as it is much thicker than normal and is made up of several parts that each play a different role. The wall is a wood stud assembly 24” o.c. laid out using advanced framing techniques. Half of the house is 2x6, but the other half throughout the double height space is 2x8 studs. On the inside, added mass from concrete counters, tile and extra thick drywall is used to store the cool in the summer and the warm in the winter. The space in between the studs is filled with open-cell spray foam for an extra air seal and the whole house is then wrapped with 1 inch of polyisocyanurate insulation to eliminate thermal breaks throughout. There is then a radiant barrier and an air space that is used to back-ventilate the final exterior skin of fiber-cement siding. This rain-screen system also acts as a whole house sun-shading device ridding the building of much of the heat even before it gets to the insulated wall.
The construction of this project was a collaboration between Saft and one of his former students, Jaron Young. Young's company, H.J. Construction, oversaw the building process and also understood it as a unique experiment. Beyond Passive House certification this home is in the final stages of attaining the first LEED platinum rating in Acadiana from the U.S. Green Building Council.
The solar array, which is laminated to the Whirlwind Weather Snap metal system, is sized at 3.264 kW. The solar laminate system enabled some of Saft's students to more fully understand photovoltaics and at the same time be involved with some cutting edge technology.
The solar laminate system is comprised of approximately 24 photovoltaic laminates each 16 inches wide and 18 feet long, and approximately ¼-inch thick. Each panel fits between the ridges of the building’s standing seam metal roofing system and face south for maximum efficiency. The solar laminate technology is lightweight (less than one pound per square foot). The combined weight of the panels is approximately 576 lbs. and covers an area of approximately 576 SF. The solar laminate technology is better at capturing off angle light than traditional crystalline solar panels. Therefore, the photovoltaic laminate array does not need to be at the perfect Tilt Angle (Slope) or Azimuth Angle (perfectly oriented South) to create a great deal of electricity. The solar laminate utilizes unique triple-junction amorphous silicon solar cells, where the blue, green and red light of the sun is absorbed in different layers of the cell. This technology results in better performance in low and diffuse light conditions.