By Heather Mullinix
Students in the building construction technology program at Tennessee Technology Center at Crossville have completed the 2015 Energy Star Concept Home and are ready to show their work to the community.
A dedication is set for noon Friday, followed by an open house during the weekend, coinciding with the annual Home Builders Association of Cumberland County Home Show.
"We know this is the first net-zero home in the county," said Steve Lane, instructor. "It may be the first in the state."
Net zero home means that, over the course of a year, the home will produce more energy than it uses. That's accomplished through a combination of energy generation with solar panels and energy efficient technology and building practices.
A 4 kilowatt solar system has been installed at the home's location across the street from the TTCC campus on Miller Ave. That will stay at the site and allow TTCC to be a Generation Partner with the Tennessee Valley Authority.
"We're the first Tennessee Board of Regents (TBR) facility to be a Generation Partner," explained Lane, who said TBR and TVA lawyers had to work out several points in the standard contract that would allow a state facility to take advantage of the program.
As a Generation Partner, TTCC will sell all of the power produced by the solar panels back to TVA at 12 cents greater than the current energy price.
The solar array will allow students at TTCC to learn how to install and care for solar panels. They can also change the tilt of the array and perform experiments.
Another unique feature is the geothermal heating and cooling system, donated by Water Furnace. One was installed in the classroom and the other in the student-built home. TTCC students are training on installing, de-installing and servicing the geothermal units.
The city of Crossville partnered with TTCC to dig 300 linear feet of trenches about five feet deep. Tubing was buried in the trenches and coolant is circulated through the tubing to provide a heating or cooling source for the home.
"The ground stays about 60 degrees year round," Lane explained. "It basically works like a car's radiator."
The coolant either removes heat from the home in the summer and deposits it in the ground, or it can be warmed by the earth in the winter, making it easier to warm to the desired temperature. The model used also works as a supplemental heat source for the water heater, depositing the home's heat during the summer at the water heater.
"When it's in air conditioning mode, you don't pay for hot water," Lane said.
The solar array and the geothermal unit will not be sold with the house, Lane explained. Geothermal, while extremely efficient, does have a higher upfront cost than tradition HVAC units, and there are specific requirements for sites to install the wells necessary to take advantage of the technology.
"We don't know where this house will be going or if the person buying it will be able to take on the expense of digging the wells," Lane said. "The duct work will remain, but we didn't think it was right to force geothermal heating and cooling on someone that may not be able to use it."
Even without those technologies, Lane said the house was built to be extremely energy efficient.
The three bedroom, two bathroom home is about 1,440 square feet, with vaulted ceilings in the living room and a trey ceiling in the master bedroom. Every bedroom has walk in closets, and the flooring includes laminate and carpet. The kitchen cabinets are cherry.
The home has about twice the insulation of a home built to current building code standards, Lane said, with walls framed with 2x6 wood instead of 2x4's, and distance between wall studs was increased to allow for more insulation. The house was also wrapped in rigid foam and the attic was air sealed with expanding foam insulation to stop air from escaping. The home is insulated to R-60.
For lighting, students used LED lighting. Lane noted these lights do have a higher up-front cost than incandescent light bulbs and the more energy efficient compact fluorescent (CFL) bulbs. However, Lane said CFL bulbs used about 70 percent of the energy of incandescent bulbs and LED lights used about 70 percent less energy than CFL bulbs. LED lights also have a long lifespan, about 15 years.
"Just those things alone knocked energy consumption down by 40 percent," Lane said. "When combined with solar energy production, it doesn't take much to produce more energy than is being used."
The home also has Energy Star windows and the exterior doors are all insulated fiberglass doors.
Little things like added insulation and sealing small cracks to prevent air loss or changing lights used may not sound like they make a big dent in energy use, Lane said, but when put together, it can make a tremendous difference.
"It's when you do a lot of little things that you make the biggest strides," He said. "It's not one thing you do. But when you put it together, you've done something."
The student-built home will sold by sealed bids. Details of the house and bid forms will be available during the open house, or prospective bidders can contact TTCC to have forms mailed, emailed or faxed.
This weekend, the community is invited to view the home Friday from noon to 2 p.m., Saturday from 9 a.m. to 5 p.m. and Sunday from noon to 4 p.m. After the open house, prospective buyers can inspect the home weekdays between 8 a.m. and 2:30 p.m. after checking in with the front office at TTCC. The winning bidder will be responsible for moving the home from school property.