Zero-energy building design A Taos design firm introduces building science for comfort and energy savings By Yvonne Pesquera
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n the race to reduce carbon dioxide emissions, homeowners typically focus on renewable energy. There’s nothing wrong with that.
But Joaquin Karcher, of Zero E Design in Taos, looks at the issue differently. Instead, he asks an intriguing question: “Why do we have to heat our homes? Because they lose heat.” The definition of a “Site Net Zero Energy” building is that the total amount of energy used is equal to the amount of renewable energy created onsite. According to the Passive House Institute of the U.S., zero net energy consumption is most cost effectively achievable with: a super-insulated building envelope, airtightness, high-performance windows, whole house ventilation system, and solar gains to capitalize on free energy from the sun.
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These are the same principles that Karcher follows. In fact, the Zero E Design website specifies that a superinsulated building envelope has insulation levels that are three to five times greater than a conventional building. “This is not guesswork,” says Karcher. “It is very precise. Every single design goes through rigorous energy modeling and gets worked out until we hit the target.” Of all the benefits (affordability, energy savings, and environmental stewardship, for example), Karcher points out that the greatest benefit is comfort. He uses a standard coffee thermos to illustrate his point. “Think of your home like an insulated thermos. You have ‘hot coffee’ and you want to keep it warm,” says Karcher. But what does comfort mean in everyday terms? After all, comfort is a subjective guideline for any homeowner. Karcher explains that a zero energy design house is the best
The definition of a “Site Net Zero Energy” building is that the total amount of energy used is equal to the amount of renewable energy created onsite.
house that money can possibly buy.
In addition to the superinsulation and airtightness, a heat exchanger lies at the heart of a whole house ventilation system. This provides fresh and filtered air at all times by exhausting and supplying fresh air to the house constantly. In this process, up to 95 percent of the energy gets recovered (compared to a house that does not have the same system). As a result, all temperatures are kept to an even 70 degrees and there is a constant supply of fresh, filtered air. Another point to be made about comfort is flexibility.