Net-Zero Energy Test House Quadruples Surplus Energy in its Second Year

Imagine living in a house that produces energy on its own so you have no electricity bills. Not only is it possible to build such a net-zero energy (NZE) home, it is now cost effective for many builders, thanks in large part to plummeting prices for solar technologies as well as more professional training in energy efficient design and a greater availability of high performance building products. But what exactly is a net-zero energy house and how do you know it will perform as advertised?

To help answer these questions, the National Institute of Standards and Technology (NIST) designed and built the Net-Zero Energy Residential Test Facility (NZERTF) two years ago. An agency within the U.S. Department of Commerce, NIST advances measurement science, standards and technology to ensure fairness in the marketplace, particularly in the areas of energy efficiency, indoor air quality and hazard prevention. In March, the NZERTF research team led by Hunter Fanney reported that the demonstration house quadrupled the amount of surplus energy it sent to the power grid during its second year of operation.

Located in Gaithersburg, Maryland, the NZERTF is a specially-designed laboratory that simulates a family of four living in an energy efficient home and tests how existing and new technologies can achieve a highly efficient, energy-producing home that can fit into any neighborhood. The house is similar in size to other single-family detached homes in Gaithersburg but was designed to be 60 percent more energy efficient than houses built to meet the 2012 version of the International Energy Conservation Code (IECC). (The IECC is a model code updated every three years and is meant to be adopted by states as their minimum building requirement.)

In the simulation, NIST researchers virtually mimic details of routine family life, including showering, cooking, turning on lights, doing laundry, watching TV, and posting on Facebook. The house even monitors and measures the heat and moisture released by the virtual family, an important factor for building designers when calculating heating, ventilating and air-conditioning (HVAC) loads.

In its second year of testing, the NZERTF successfully eliminated an annual electricity bill of about $3,670, mostly by reducing energy use. In addition, the rooftop solar power system generated a total of 13,717 kilowatt hours (kWh) of electricity – a slight gain over the previous year and “equivalent to the energy generated by burning more than seven tons of coal or about 1,000 gallons of oil,” according to NIST. The reduced energy use combined with the extra solar-energy generation resulted in the heftier energy surplus in the second test year. Because Maryland has a net-metering law, this surplus of over 2,000 kWh sent back to the power grid earned the house an $80 refund check from the local utility (on top of the $3,670 in energy savings).

The Net-Zero Energy Residential Test Facility is just one important facet of federal energy research. More progress is anticipated with the Obama administration’s proposal to significantly increase investment into clean energy research and development in fiscal year (FY) 2017, with the goal of doubling current funding by 2021. As summarized in EESI’s FY 2017 budget proposal brief, the President’s proposed budget includes a 40 percent increase in funding for the Department of Energy’s Office of Energy Efficiency and Renewable Energy programs including building technologies; a 24 percent increase for DOE’s bioenergy programs; an increase of $25 million for USDA research in sustainable bioenergy; and $185 million for the Research and Technology program at the Department of Housing and Urban Development, including $5 million for a new Multifamily Pilot to Reduce Energy Consumption.

 

Author: Taotao Luo