Net-Zero Model Home Improves Energy Efficiency

How would you like the power company to pay you instead of a sending you a bill? That could be a reality if you lived in a so-called net-zero house that produces its own power while sipping energy like a miser.  The overall concept is that the residence uses no more energy than it creates.

The state-of-the-art, net-zero house that serves as an energy-conservation laboratory in Maryland has reportedly become so efficient that it quadrupled its energy surplus in its second full year of experimentation.

This is the latest in bragging rights from creators at the National Institute of Standards and Technology or NIST. Instead of being inhabited by a living family, the model home is programmed to simulate the effect a family has via daily living, from how many times light switches are turned on and off to typical humidity levels.  The simulated family is allowed all of the modern comforts of a typical family, from comfortable indoor temperatures to technology-based entertainment.

The four-bedroom home has its own rooftop solar grid along with several smart-design features that help it meet LEED Platinum standards from the U.S. Green Building Council. The traditional-looking, two-story house has 2,700 square feet of living space.  In Maryland, that size house would typically incur an annual power bill of over $3,500. Instead, the photovoltaic panels atop the roof generate enough power for this home to run, plus a small surplus of power that could be returned to the central power grid. The project reported a surplus of 1,655 annual kilowatt-hours over the previous test year.  In a year's time, the rooftop PV system generated more than 13,700 kilowatt-hours of electricity.

While the solar rooftop may look like the most impressive feature of the net-zero home, it's not the primary means of making it a standard bearer. Senior research scientist A. Hunter Fanney explained: "If all the solar panels were taken off the [home], it would still use 60 percent less energy than homes currently built to code." In other words, energy efficiency itself is the main strength.

For second-year improvements, tweaks to the home's heating system greatly improved efficiency without sacrificing comfort, Fanney said. Another savings came from reducing the outdoor ventilation rate.

TriplePundit asked Fanney to explain how practical the model house would be for the typical family.  As for the ability to construct it, he told us the home could be replicated because the technology being used is off-the-shelf and readily available.  However, cost-effectiveness could be a challenge for many people, since the house includes features that put it at approximately $250 per square foot of living area. "Compared to an identical house that would meet the 2015 International Energy Conservation Code, it costs approximately $120,000 more."

This model home report comes as various industry standards are moving toward net-zero homes being more readily available on the market and this being the new construction standard by approximately 2030. Demonstration projects like this are showing what can be done with houses that need not depend on a power grid. However, current policies of many utilities and the communities they serve can often be prohibitive to homeowners.  For instance, the incentives for homeowners to create their own solar power in the state of Nevada was recently undermined by a policy change.

We asked LEED fellow, architect and author Eric Corey Freed to weigh-in on what this model home means for the green building industry.  He responded: "The key to solving the challenge of climate change lies in fixing our buildings and transforming all of them to be net-zero energy. Not only will this slash our carbon emissions, but will save building and homeowners billions in energy costs.

"The [Maryland test-house] shows us how the key to achieving net-zero is in building an efficient building (with a tiny base load) in the first place. My hope is this model will serve as a catalyst for the industry to develop new financial models and incentives for existing building owners to retrofit and upgrade their buildings."

We asked NIST's top scientist how the average homeowner can save energy even without a new home, and Fanney offered these tips, in order of cost-effectiveness:

1. Conservation -- sealing of cracks/openings to prevent unwanted air from leaking into or from the house, followed by increasing the amount of thermal insulation in the exterior walls/ceiling of the structure.


2. More efficient heating/cooling and water-heating equipment and appliances.


3. Addition of renewables in the form of photovoltaic panels or a solar hot-water system.

You can take a look at the model net-zero home here and get some construction or renovation tips for yourself.

Image courtesy of the National Institute of Standards and Technology