The ‘Power Haus’ by Josh Wynne Construction in Sarasota, Florida has achieved the lowest HERS rating on record in the U.S., a negative 22, with an elegant, well-crafted design. Earning 118 LEED points the home is just shy of also becoming the highest scoring LEED home in the country by 1.5 points to the Helenowski Residence in Chicago, which holds the highest known score at 119.5.
With a negative HERS score, the Power Haus is producing more energy than it consumes on a yearly net basis. The home has a 14.2 kW Uni-Solar Flex-Lite amorphous silica (peel and stick) array to bring it into so-called climate positive territory. Not considering the solar, Power Haus would still achieve a 42 HERS index which is noteworthy in and of itself. They were able to achieve such energy savings through a variety of passive and technological applications.
Power Haus is carefully situated within large existing trees, of which shadow lines were studied in conjunction with large 4’ eaves to provide protection from the Florida sun. Importance was paid to the ability to open the home to the outdoors and capture the westerly breeze.
To assist in the natural ventilation the house is equipped with ceiling fans, including one 8’ in diameter in the great room, and large expanses of operable windows and doors. An independent dehumidification was installed to counter the Florida humidity and increase the number of natural ventilation days.
The building envelop is a standard CMU construction wall type with foam insulation filled within the open cells of the CMU block (R-15) and VR-Plus II permeable radiant barrier (R-7.2) to fight against thermal bridging. Closed cell bio-based R-30 spray foam insulation was applied exterior of the moisture barrier to allow for the elegant interior tongue and groove ceiling and glu-lam beams.
With durability an important goal the builder pursued impact resistant, low-e, argon filled windows from Jeld Wen with a 0.3 SHGC and 0.19 U-value.
Technological applications include 21 SEER Carrier Infinity HVAC system, Eternal gas tankless hybrid water heater, Energy Star appliances and 100% LED lighting. Power Haus is fully automated with real-time energy production and lighting controls available on an iPad or iPhone through Elan Home Systems. In addition to energy efficiency, the home shows a commitment to sustainability with polished concrete floors, clay wall finish, and reclaimed cypress or FSC wood throughout the house.
Outside the green home, landscape irrigation is eliminated through the use of a native and drought tolerant plant palate. Rainwater is captured from 100% of the roof area and feeds a 6,000-gallon cistern for future use interior (once the code catches up and allows filtered rainwater at the tap) and is currently used within the horse stables. Interior water use is reduced through low-flow fixtures and dual-flush toilets fed with greywater.
Josh Wynne has a great history of producing sustainable homes, previously designing and constructing the former highest scoring LEED home, Codding Cottage. However, it is not about scoring LEED points, Josh stated, but about setting strong environmental goals and delivering a quality product. ‘Price Up’ next for Josh Wynne Construction is a new construction home with a -50 HERS Index — stay tuned for updates.
It should be noted that The Power Haus also scored the highest rating possible through NAHB Green (Emerald) and Florida Green Building Coalition (Platinum), in addition to LEED Platinum certification.
Photo Credit: Matt McCourney.
Article tags: Florida, LEED Platinum, NAHB Emerald, net-zero, residential