Zenergy House: Green Renovation Portrait
June 21, 2010
Designing green features into a new structure is a far easier process than renovating an existing home with green elements. But this was the challenge that was undertaken by Residential Energy Assessment Services Inc. (REAS), Los Angeles, which recently unveiled its green residential remodel project located in Studio City, Calif.
Zenergy House was conceived as a living example and educational tool for average people to learn about and incorporate greener elements into their home environment. The one-story home was originally built in 1950 and includes three bedrooms, three bathrooms, 2,450-square-feet of living space, and a pool. The home was selected because of its unique architecture and because its size reflects the national average for square footage.
Tammy Schwolsky, CEO, REAS Inc., and owner of Zenergy House, noted that the reason for this project was to “convince both the public and the building industry that we can restore our poorly performing homes and make them more comfortable, affordable to operate, healthier to live in, and healthier for the planet ... it is doable.”
OVERSIZED HVACREAS is a consulting, auditing, and training firm that provides cost-saving energy solutions to owners and agencies who want to implement energy-efficient technologies, water conservation, and renewable energy systems. With Zenergy House, Schwolsky wanted to create a home that exemplified the benefits of a high performance green home, which include improved health, safety, comfort, and the ability to protect property values from escalating energy costs. Where else to start than with the HVAC system?
The home’s previous HVAC system was oversized, consisting of two 3-ton air conditioning units and two furnaces. An energy audit showed that the original ducts had over 20 percent leakage, an undersized return, and badly designed air distribution. Rick Chitwood, owner, Chitwood Energy Management and Home Performance, Mt. Shasta, Calif., signed on to design the new high-performance HVAC system. Vince Cord, owner, Poly-Tech Environmental Inc., Sherman Oaks, Calif., a firm that specializes in healthy and energy efficient HVAC system retrofits, new installations, and consulting, was hired and trained to install the new energy-efficient HVAC system for the home.
“For heating and cooling the living space, we used a 4-ton, First Company air handler with ECM blower motor, DX cooling coil, and hot water heating coil, along with a 3-ton Freus water-cooled condenser,” said Cord. “Together, the system approaches a rating of 20 SEER. The air handler was programmed to move 1,420 cfm in order to maximize efficiency in a climate with low humidity.”
The inefficient water heater was replaced with a high output, 99.1-percent efficient, closed combustion, condensing water heating tank, which was connected to the variable speed air handler to provide domestic hot water and space heating.
All existing ducting was in poor condition and had to be removed. A newly designed duct system was installed, and most of the ductwork was relocated to the insulated and air-sealed crawlspace below the floor to minimize duct losses. Almost all the supply registers were relocated to the floor for less friction loss and better air mixing. The new flex duct system was insulated to R-6, designed for .5-inch w.c. static pressure, and sealed to 2 percent leakage, including the air handler.
“We had a little trouble finding space for a large enough duct to move sufficient air from the insulated and air-sealed attic, which is where the air handler was located, to the crawl space, where most of the supply ducting was located,” said Cord. “The problem was easily solved by installing some custom-made sheet metal ducting.”
IAQ was very important, so Cord installed a 24- by 24- by 4-inch MERV 11 filter, enclosed in a custom made, airtight housing, that was fitted with gasketing to prevent any air bypass around the filter media. “The filter system not only helps with air quality, but also helps with energy efficiency, by keeping the coils and blower super clean; in fact the air handler will not require any cleaning for many years.”
Since completion of the Zenergy House, REAS has provided this efficient HVAC solution for three of its Home Performance clients.
OTHER ENERGY-SAVING ELEMENTSIn addition to the highly-efficient HVAC system, a 2.4 kWh solar PV system was installed, along with LED lights, energy- and water-efficient appliances, and a smart irrigation controller. Inefficient and leaky existing windows were also replaced, and the crawlspace and two small attics were air sealed. Drought tolerant landscaping was planted, which, together with the dual flush toilets and engineered shower heads and fixtures, reduced the home’s water usage by 70 percent.
The EcoView residential home energy management system from Advanced Telemetry, San Diego, was installed to display electricity consumption in real-time. The system also enables access to and control of integrated peripheral devices such as thermostats, light switches, and even water meters. “The homeowner can see real-time that as he adjusts his energy loads inside the home, the impact that this has on his energy consumption and on his energy costs,” said Gus Ezcurra, president, Advanced Telemetry.
EcoView can interface with any existing or newly installed system, and the devices that interface with the HVAC system are usually installed and configured in less than 20 minutes, noted Ezcurra. “The product is intended to be installed in any type of home or business where the occupant would like to gain control over his energy consumption and modify his behavior in order to save money.”
Many of the products used in the Zenergy House were donated by manufacturers, so a total cost for this green renovation is not available. Schwolsky did note that the home is now a net-zero energy home and by the end of the year the energy produced should equal the electricity used.
“The Zenergy House shows that the benefits of energy audits and retrofits go way beyond lowering utility bills,” said Schwolsky. “An energy upgrade can provide greater comfort levels, improved indoor air quality, and durability. We believe that everyone is looking to save money and secure their investment. Unfortunately, people still believe that an energy upgrade or tune-up is expensive and hard to do. The message that energy efficiency has a payback of usually 2 to 5 years is still uncommon knowledge.”
As the owner of the Zenergy House, Schwolsky is very happy with the results. “Collaboration was the key to this project’s success, and we will continue to create opportunities for others to visit, learn, and hopefully be inspired to create their own Zenergy House.”
Visit www.greenhomespecialists.com for more information on Zenergy House; for Poly-Tech Environmental, visit www.greenhomeairsystems.com; and for Advanced Telemetry, visit www.advancedtelemetry.com.
Publication date: 06/21/2010