Considerations for Building Net-Zero Homes in California

Originally published by: Napa Valley RegisterNovember 24, 2018

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Building green homes in Napa requires a combination of abiding by national standards, learning about the local natural environment and being aware of how light and heat change over the course of a day in Napa Valley.

A typical green home rewards its owner by using less energy and water, providing a monthly saving on utilities, and maintaining cleaner indoor air than a conventional home. There are many aspects of green building to consider, from heating to materials to protecting local bird populations.

Mike Zimmer, chief building official of Napa County, said mandatory and voluntary measures affect green residential home construction.

“The California Green Building Standards Code (which took effect Aug. 1, 2009) is the nation’s first statewide green building code,” said Zimmer.

Zimmer said even individuals doing a remodel or a small room addition can review “green elements” of home construction with a contractor.

In California, builders should be aware of the “southwest exposure,” the direction in which sunlight comes into a house.

“It helps if you orient the house so the windows and openings face the southeast. That way, you can take in more sunlight during the day. Not having to turn the lights on early in the morning and late at night saves you energy,” said Zimmer.

Zimmer said people who are low-income or on a budget can get assistance to make a home green by looking to the appropriate agency.

“If you’re retired and on a fixed income, different agencies in the state will repair or replace certain items for free. For example, the California Conservation Corps (CCC) will replace refrigerators, upgrade lighting, and change water fixtures for you. The California Department of Housing will assist with weatherization,” said Zimmer.

Kenneth Russo, founder of Green Builder, a Vallejo-based contractor who builds green homes in Napa, advises several materials for green homes.

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“When you build where there is a risk of fires, you should use fire-resistant glass. (You should also have) metal shutters on the exterior of windows so you may close (them) and prevent hot (embers) from entering the home. I recommend metal stud construction for homes as well. It’s economical, fire-resistant, and recyclable. It doesn’t get termites or wood rot,” said Russo.

Russo also recommends a roof made of refractive material, which holds heat in during the winter and keeps heat out during the summer.

“It avoids the stack effect which allows infiltration of hot air into enclosed spaces. That way you do not waste heat or cooled air anywhere in the house. (Another thing you can do) is install vapor barriers underneath the home,” said Russo.

Bob Massaro, CEO of Healthy Buildings in Napa, said the best strategy is starting with a “really good building envelope.”

“Summer months in the Napa Valley can get quite warm. We design and build each home’s ‘building envelope,’ walls, floors and roofs, to be very energy efficient. (This way) the residents are always comfortable and…the requirement for using air conditioning is minimized. We also put solar power on our homes to make sure each home produces as much energy as it consumes. In the building industry, that is called ‘zero-net energy,’” said Massaro.

Massaro advises not using wood on the outside of a home.

“It’s combustible and not allowed in many areas because of fire danger. Wood also does not weather well. We use composite materials, metal siding, and ‘Smart Siding.’ These are durable, low maintenance products that are quite fire resistant,” said Massaro.

Jarrod Denton, architect with Signum Architecture, LLP in St. Helena, said if you build a well-designed and constructed home in Napa Valley, you will not need air conditioning.

“Make sure you get high-performance windows and doors. They perform eight-times better than conventional windows and doors. A well-insulated, airtight home is almost like having a Gore-Tex jacket in a rainstorm. Moisture can escape out. Nothing is allowed in unless you choose to open up the window or doors for a pleasant breeze,” said Denton.