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Monitoring Energy Use

Launch Slideshow

Net Zero House

Performance Monitoring Equipment

Net Zero House

Performance Monitoring Equipment

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    Monitoring equipment is critical for measuring the performance of individual components as well as overall system efficiency. A wind data logger displays current wind speed and tracks wind speed over time.

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    A dedicated meter records the AC power produced by the turbine.

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    A meter on the heat pump constantly monitors temperature and flow of water into and out of the unit and converts the data into Btu output.

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    A flow meter on the domestic hot water line measures hot-water consumption.

Because we live in a rural area, we spend much of our time at home. We are a family of four: my wife and I and our two children, ages 10 and 16. My wife works from a home office, and nearly all of our meals are cooked at home. Though the house has been designed for maximum efficiency, our family is keenly aware of how to “operate” the house so it reaches its potential.

In addition to the power company’s electrical meter, the house has several monitoring devices that give us regular feedback — a wind data logger, a kWh meter on the turbine, a kWh meter and a Btu meter on the heat pump, and a flow meter on the domestic hot water line at the water softener. With these meters and the main utility meter, I can track how much energy we produce given the amount of available wind and how many kilowatts (or Btu) of energy the heat pump produces for both space heating and hot water. Because everything is electric, I can simply read the utility meter and subtract our total energy production from the wind turbine to arrive at our net gain or use. Monitoring energy use in a single unit is not only easy to understand, but the feedback gives us incentive to try to lower the usage. As we do this, certain habits change and become new habits, and small changes add up.

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To date, after three years, the turbine has produced around 20,000 kWh and we’ve consumed around 21,000 — a net use of only 1,000 kWh, costing around $140 for all three years. If we didn’t have the windmill and were paying for all our electricity, it would have cost about $80 per month for heat and utilities — a sustainable energy cost. The larger point is that building a low-load house in a cold climate is not only affordable but readily achievable, not in the future, but right now.

David Pill is an architect in Shelburne, Vt. The home featured here achieved LEED Platinum and has a HERS score of 0.