Net-zero energy building is still a far-off goal for some builders, but it will be reality, ready or not, in just a few short years in California. So now is the time for the industry to hone its green-building formulas and align with manufacturer partners to drive more energy-efficient product.
One of the larger challenges facing net-zero energy building is also one of the busiest growing sectors in residential construction: multifamily product. A leader in sustainable building, Meritage Homes identified an infill site in Irvine to apply its knowledge of zero-energy building practices to attached housing. The site was developed by Meritage Land Co. (MLC), a subsidiary Meritage Homes launched specifically to identify and repurpose infill areas for such projects. The location also happens to be a perfect spot to access job centers and reduce commute times.
The project, which breaks ground next spring, will eventually be one of the state’s first examples of net-zero multifamily housing, with 44 three-story townhomes ranging from 1,600 to 2,200 square feet each. The project design encompasses eight blocks of for-sale triplexes and duplexes.
Through a partnership with Southern California Edison (SCE) and the Electric Power Research Institute (EPRI), Meritage seeks to foster best practices in net-zero energy for multifamily development. With new utility strategies and advanced industry technology, EPRI is guiding Meritage and architect KTGY to value-engineer and translate both commercial and single-family applications to this new, attached-housing model.
“[For the new project], we redesigned the traditional exterior-wall structure with a new, insulated-stucco product to achieve better performance at a competitive cost,” explains Ram Narayanamurthy, EPRI principal program manager.
The design features will resemble those used in Meritage's single-family homes and incorporate new technologies that utilize project scale to maintain buyer value. EPRI is applying lessons learned from its work with Meritage on a net-zero energy community in Fontana, as well as from a new venture with De Young Properties on a net-zero energy, grid-connected, 36-home community, to further enhance the multifamily project for the builder, owners, and surrounding community.
To optimize the development's efficiency, the homes will incorporate spray foam insulation, LED lighting, and energy-efficient appliances. A high-performance flat roof will require working with cool-roof membranes and installing insulation in the roof cavity, technologies not prevalent in single-family housing.
One challenge the team faced early on was how to supply hot water efficiently throughout the three-story townhomes while meeting state energy mandates. The solution was to add heat-pump water heaters using demand-based recirculation. The homes also use an unconventional approach to heating and cooling, blending one standard split unit for the second and third stories and a small mini-split unit for the base floor to minimize energy use.
A New Slant on Solar
The multifamily project is affording the development team the opportunity to look at renewable energy differently. Traditionally, the industry has lacked a good way to directly connect each resident with a fair allotment of rooftop solar energy. A new and innovative program started by SCE called Virtual Net Metering for Multifamily was recently expanded by the California Public Utilities Commission from low-income projects only to also be available for market rate projects and allows allocation of output from a community solar system to be distributed to homeowners.
A community solar system offers the added benefit of conserving both space and cost. Many multifamily communities are space constrained and lack the room for unit-specific inverters and batteries. A community system, in contrast, maximizes space by accommodating a single inverter and a more-contiguous solar roof array that allows for optimum orientation. And there's an obvious cost benefit when only one inverter is needed.
“We're going to try to produce 3.7 kilowatts per home,” says Narayanamurthy. “We're working with Meritage to optimize the energy load by capturing energy in units of five homes and then redistributing it. This will drive down the cost of solar to the customers.”
“It's been hard to provide communal energy resources back to the individual residents who sponsor the programs,” says C.R. Herro, vice president of environmental affairs at Meritage Homes. “New policies had to be made; new relationships with utilities had to be made to aggregate and then redistribute energy; and [we had to align] with suppliers and trades to do this all cost-effectively for our homeowners. It’s exciting to give new homeowners the ability to have a well-built home that can also participate in the economic benefits of renewable energy.”
Many attached projects don’t accommodate solar, and their owners may not have “ownership” of the roof in order to leverage the benefits of the technology. The EPRI program for the first time enables people in urban areas who live in attached housing to participate. Plus, Meritage is investigating ways to absorb the cost of the solar energy system into the homeowner-association fee structure to remove the up-front costs and help pay for the system over time.
Meritage's townhomes will be sold through model units and a community sales office in late 2018.