Striving for Net Zero water: Whirlpool Corporation’s ReNEWW Hous
By E. W. Bob Boulware, P.E., MBA; Dr. Markus Lenger; and Eric Bowler
The ReNEWW House is a 2000 square foot, 1920s vintage bungalow-style house, located in West Lafayette, Ind., next to Purdue University’s campus. ReNEWW stands for Retrofitted Net Zero Energy, Water & Waste, and reflects the vision of the project – to retrofit an old home to be resource efficient by generating its own renewable energy, capturing and purifying rainwater for it water needs, and sending no waste to the landfill.
The house is a collaborative effort between Whirlpool Corporation and Purdue University to provide a sustainable living public showcase and a live-in laboratory for student engineers who live, study and research the new generation of resource efficient appliances.
The concept of Net Zero energy living has been popularized for residential use due to the recent reduction in costs achieved by solar photovoltaic (PV) technology. To achieve the Net Zero energy status, the ReNEWW House underwent a deep energy retrofit over the summer of 2014. New triple-pane windows and improved doors were installed; spray foam insulation was applied to wall and attic cavities; a geothermal heat pump replaced the natural gas furnace and split AC system; and a solar PVT (photovoltaic & thermal) array was introduced to generate onsite energy.
Net Zero water is a relatively new concept that has been achieved by only a few facilities. The goal for the ReNEWW House is to capture rainwater onsite without requiring supplemental ground water from a well or a water utility.
The first step to achieve the goal of Net Zero water was to minimize the amount of water needed by the occupants, which included replacing the existing fixtures. The fixtures installed in the kitchen include an improved dishwasher by KitchenAid that incorporates a novel filter that removes food particles during the wash cycle and significantly reduces the amount of water required. The old five-plus gallon per flush toilets and four gallon per minute showers were replaced with state-of-the-art fixtures supplied by Kohler, a partner in the ReNEWW House project. The end result of this upgrade was an over 60 percent reduction in fixture water use.
Once the demand for water was reduced, the resultant water demand was designed to be collected from the 1,600 square feet roof surface with the expectation it will harvest approximately 34,000 gallons per year. To assure good quality, end-use water, the raw rainwater is pre-filtered before going into the storage tanks with a WISY rainwater filter, which diverts roof debris away from the stored rainwater by wasting the initial portion of a rain event.
When the 280-micron screen is thoroughly wetted, capillary action then diverts the rainwater through the screen into two 1,500-gallon underground tanks. Water exiting the tanks is then made potable by filtration through a 1 micron absolute filter and activated carbon block, and disinfection by exposure to ultraviolet light.
The house further reduces potable water demand through the internal reuse of greywater. The use of greywater begins with a water audit to quantify the expected greywater sources and potential greywater uses. In the case of the ReNEWW House, greywater provided from the shower and lavatory was expected to be slightly more than the flushing requirements for the low flush toilets (54 gallons per day versus 42 gallons per day). Any excess water available will be used to supplement the washing machines water needs.
Kohler had previously studied existing greywater processing systems on the market and all were found to be disappointing for various reasons: either providing effluent corrosive to appliances, or being too costly to operate to be economically justified (Investigation of Residential Water Reuse Technologies by Bill Kuru, PhD and Mike Luettgen, P.E.). Investigation of new technology led the design team to CleanBlu, a California based company that specializes in innovative solutions to processing contaminated water streams.
CleanBlu’s revolutionary prototype Greywater Processing System (GPS), specifically developed for validation at the ReNEWW House, consists of a core biological treatment stage to metabolize contamination and a second advanced ozonation stage where water quality is stored and maintained before being distributed through the greywater supply system.
The system has a maximum treatment capacity of 450 gallons per day, and all aspects of the GPS are monitored in real time with system updates and process control changes able to be managed remotely via the Internet or smartphone app. The system is essentially maintenance free, having no filters to change or maintain, with only bi-annual replenishment of microbial concentrate being required. Power consumption to process the greywater is less than for a 40 watt lamp bulb.
The technology included in this water management retrofit is a mixture of the very old and very new. Rainwater collection has been used for thousands of years, while the installation of the Greywater Processing System is the latest innovation in water management. Matching the two technologies is projected to provide 99 percent of the potable water needed while reducing sewage effluent up to 60 percent.
As a living research facility, the ReNEWW House has extensive instrumentation installed throughout that will monitor progress toward meeting Net Zero Goals. Along with water flow throughout the house, temperatures, relative humidity, and electricity consumption will be studied to verify actual versus projected savings.
As water and energy conservation become a more prominent issue in today’s world, the ground breaking application of old and new technology applied at the ReNEWW House opens the door to new ideas in how modern facilities will be designed in the future.
E.W. Bob Boulware, P.E., is project designer and president of Design-Aire Engineering, an Indianapolis based engineering firm specializing in energy and resource efficient building systems. Boulware is past president of the American Rainwater Catchment Systems Association, member of the Board of Advisors of the International Rain Harvesting Alliance, has served on IAPMO and ICC national code councils, author of “Alternative Water Sources and Waste Management Systems,” and principal author of the ARCSA/ASPE/ANSI 63 Rainwater Catchment Design Standard. Contact Boulware at BBoulware@DAEngineering.com, or 317-464-9090.
Dr. Markus Lenger is CEO and co-founder of CleanBlu Corporation, which is dedicated to innovating wastewater industry processes to the consumer level, using a sustainable and ecological approach. Dr. Lenger holds degrees in electrical engineering, laser technology and physics and during his 30-year career in wastewater has developed, patented and marketed an at-source, in-situ FOG reduction system and a FOG to biofuel feedstock conversion system. Contact Dr. Lenger at firstname.lastname@example.org, or 949-200-6226.
Eric Bowler is a senior engineer, specializing in residential energy and water systems, at Whirlpool Corporation in Benton Harbor, Mich. He is the program lead of the ReNEWW House a sustainable living showcase and living laboratory research collaboration between Purdue University and Whirlpool Corporation. Bowler holds a dual M.S. in Sustainable Energy Engineering from the Royal Institute of Technology, Stockholm (KTH) and the Polytechnic University in Turin (PoliTo). Bowler was runner up in the 2012 Hult Prize, the world’s largest student competition for social good, with his business case on micro financed solar lanterns for the African market. Contact Boweler at Eric_J_Bowler@Whirlpool.com, or 269-923-3042.