Calif. home is certified “Net Zero”

Calif. home is certified “Net Zero”

A cutting-edge system incorporates solar, an air-to-water heat pump, and radiant heating and cooling systems.

CARMEL VALLEY, CALIF. – Bryan Jaeger is a building contractor, so when it came time to build his own home on a 146 acre ranch amid the green, rolling hills of southern California, he put a lot of thought into how he wanted it heated and cooled.

Jaeger’s primary concerns were value and comfort, which at first made him wary of green technology. “I thought it would be too expensive,” he said, “Or that I would have to make sacrifices in my design.”

But after his daughter prompted him to take a solar homes tour, Jaeger attended a Net Zero Energy seminar presented by David Knight of Monterey Energy Group, a mechanical engineering and consulting firm based in Pacific Grove, Calif. Knight is also the founder of Net Zero Energy Certified, a consulting company that is in the process of certifying more than 60 Net Zero Energy buildings.

The Net Zero concept is a simple one: your home produces the same or more energy than you consume on an annual basis. Jaeger was sold on the concept, and Knight, his partner Abe Stallcup, PE, and the staff at MEG designed a grid-tied solar electric system for the new home sized to provide all the energy for appliances, lights, heating, cooling and domestic hot water.

Western Sun Systems installed the solar system. The owner-operator of Western Sun is Jim Dunn, who has been in the HVAC business for the past 30 years. Two years ago he took the plunge and began doing solar work exclusively.

“I love it,” Dunn said about his work. “It just feels like the right thing to do. I’ve compared it sometimes to being a farmer, because it’s as if you’re harvesting a natural resource. There’s something enjoyable about that.”

Western Sun installed solar panels across 429 sq. ft. of roof that will generate 11,100 kWh of electricity annually. “These panels are designed to go for 25 years,” Dunn explained, “and in the past five years inverters have become really reliable. A lot of these systems are practically bulletproof.”

For the combined heating, cooling and domestic water systems, Jaeger turned to Lockwood Mechanical. Lockwood has been in business the past 19 years, and for the past ten has been headquartered in Marina, Calif. The six-man shop works anywhere from 15 to 25 jobs at a time, doing mostly residential new construction, and mainly serving the Monterey Peninsula and surrounding communities.

Bryan Jaeger turned to Lockwood in part because of a past working relationship -- Lockwood has done the mechanical work on a number of the homes Jaeger has built -- but also because of a niche Lockwood has made for itself in the market.

“The primary focus of our business is radiant heating and HVAC,” explained owner/operator John Lockwood. “The standard HVAC market we stay out of, but a lot of the larger, newer homes have integrated HVAC/radiant systems, and we’re somewhat unique in our area in that we’re able to handle both the dry side and the wet side.”

This capability was critical for the Jaeger home, because the heart of the heating and cooling system is a Daikin Altherma air-to-water heat pump. Long in service in Japan and Europe, the Jaeger home marks the unit’s first installation in California. The variable speed heat pump is able to finely adjust to changing demands – the same principle behind modern modulating condensing boilers. Because of this it is able to deliver the kind of high efficiencies needed in a Net Zero home.

“A standard heat pump may only produce a coefficient of 2, 2.5 in some installations,” John Lockwood said. “In a relatively mild climate, the Altherma can run between 3.8 and 4.0 with very little energy wasted.”

As with any heat pump, exacting design is critical. Heating and cooling loads, supply water temperature and equipment sizing must all be calculated precisely to attain those high efficiencies.

Lockwood Mechanical spent two weeks with the heating system and another week installing the radiant tube heating and controls. “The Altherma has a built-in outdoor reset,” Lockwood said. The unit will do outdoor reset or run on constant delivery, which made integrating the systems relatively simple.

Lockwood Mechanical installed 1,800 linear feet of ½-in. barrier PEX, polystyrene insulation over slab, with a mortar-bed float and brick veneer. In addition, they installed nearly 500 sq. ft. of Ecowarm, a prefabricated radiant floor panel product that was used under all the hardwood floors.

One of the more innovative aspects of the system is the ceiling-mounted radiant cooling system. “It’s not yet installed,” Lockwood said, “but it’s prepped and set up.” The fan-coil system will work off of chilled water from the Altherma. Four thermostats allow the homeowners to control room temperatures based on use.

Lockwood’s only remaining concern was with the system was meeting domestic hot water loads. His solution was to boost capacity with an 80-gal. storage tank.

Installation was completed in January, and the system has been up and running, quietly, efficiency, and to its owners complete satisfaction ever since. Now the Jaegers are looking forward to having their house included on the next solar home tour.