Granbury Members’ Home Really
Measures Up in Energy Efficiency
By all accounts and measures, their home was sealed tighter than a drum.
Daniel and Sharee Lowe received their first introduction to United during an energy audit. As energy advisors probed and performed the usual procedures to test energy efficiency, they were shocked by their findings and couldn’t find much room for improvement.
What they didn’t know at the time was that the Lowe’s new home was sketched by Sharee and built by Sharee’s father, Lacee Lamphere, whose own home is one of the most efficiently built in the state of Texas.
Lamphere owns Innovative Applications Corporation, which focuses on designing energy efficient, low maintenance residential homes that are built to last longer than typical structures.
Lamphere’s personal home received a rating from the Home Energy Rating System (HERS), which requires building beyond typical energy efficiency standards. A HERS rating is the industry standard by which a home’s energy efficiency is measured.
According to the U.S. Department of Energy, a typical home scores 130 on the HERS index, and a standard new home scores at 100. This standard new home score is used as the baseline for scoring.
A new home with a HERS rating of 60 means it is 40 percent more efficient than a standard new home. Mr. Lamphere’s home is so efficient that his home actually received a negative score. This means his home produces more energy than it consumes, which is an even more impressive feat considering it encompases 7,436 square feet.
The home’s special features include SIPs panels, a geothermal heat pump system, LED lighting, solar panels and a fully automated smart home with WiFi connected appliances.
SIPs panels, also known as Structural Insulated Panels, largely give Lamphere’s home its negative HERS rating. SIP panels consist of an insulated foam core sandwiched between two structural facings, such as oriented strand board. A six-inch SIP wall has an R-value of 25. For comparison, a standard 6-inch stud wall with fiberglass insulation comes in with an R- 19 rating.
SIPs also are extremely airtight. Oak Ridge National Laboratories built two identical 2,600-square-foot homes in an experiment where one was made of SIPs and one with conventional wood framing and fiberglass insulation.
“The SIP research home was five times more airtight than the wood-frame when measured by a blower door test,” the results stated.
Another major reason for Lamphere’s HERS index score is due to his heating and cooling system. The home utilizes a geothermal heat pump system, which uses the ground to heat and cool buildings rather than the outside air.
“Like a cave, this ground temperature is warmer than the air above it during the winter and cooler than the air in the summer,” according to a Department of Energy report. “The GHP takes advantage of this by exchanging heat with the earth through a ground heat exchanger.”
With the ground staying at a constant temperature compared to the air above, the geothermal unit will run more consistently as a result.
Many of these same efficiencies featured in Lamphere’s home also appear in Daniel and Sharee’s home. They also have SIPs panel construction, high efficiency windows and LED lights throughout the home.
Unlike Lamphere’s geothermal heat pump system, the Lowe’s home uses a ductless mini-split heat pump system. In a ductless mini-split system there is only one outside compressor which is linked to one or multiple indoor air handling units with a refrigerant line.
“Duct losses can account for more than 30 percent of energy consumption for space conditioning, especially if the ducts are in an unconditioned space such as an attic,” according to the Department of Energy. The ductless system avoids these losses.
The Lowe’s home boasts two efficient 21 SEER ductless mini-split heat pump systems. SEER stands for Seasonal Energy Efficiency Ratio and is the rating system used to measure the efficiency of the unit. Daniel and Sharee’s units were so efficient, they received the maximum United rebate of $500 per unit through the co-op’s Energy Innovation Heat Pump Rebate.
“The rebate was very beneficial,” Sharee said. “New homes are expensive, but it has definitely paid off to make smart energy choices. Although the energy efficient choices have cost us a little bit more to begin with, it was great to learn we received this reward from the co-op in return.”
Each system has five heads connected to one condenser, giving the Lowes the ability to control 10 individual areas to heat and cool. The mini-split system lets them control the individual temperature in each room where an indoor air handler head is located.
“The fact that I can have a meat locker for my husband, who wants it always cold, and I can be nice and cozy in another part of the home is great,” Sharee said.
To test the Lowe’s home, United conducted a blower-door test to measure the tightness of their home. The test showed the home had an ACH/50 rating of 2.05. The expression ACH/50 refers to the number of times in one hour that the inside air volume is replaced with outside air at a house pressure difference of 50 pascals. In climate zone 3, the 2012 IECC code states that a home should have less than 3 ACH/50. The Lowe home surpassed this standard, making it unquestionably a very tight and efficient home, and a model for energy-efficient design.