Jaspal Subhlok, a computer science professor at the University of Houston, thought his 1920s-era Montrose bungalow was shipshape when it came to electricity efficiency.
Subhlok, who has owned the house since 2004, typically keeps his house at a moderate 78 degrees in the summer. He bought an energy-efficient refrigerator, energy-saving light bulbs and installed double-layered window shades for his front windows, to keep out the worst of Houston’s wilting summer heat.
But Arcadio Padilla, an electricity auditor who visited Subhlok courtesy of his retail electric provider, Reliant Energy, found a hole in an air conditioning unit that was blowing costly cool air uselessly into the attic. Repairing it could mean 10 percent in savings.
The red flag for Padilla was the high percentage of summertime electricity use by Subhlok’s air conditioner, even though his overall electricity usage was low for a Houston electric customer.
“He was consuming approximately 80 percent of his usage for air conditioning — 15 percent more than I would expect,” Padilla said.
“And we found the 15 percent,” Padilla said, pointing to the gash in the supply plenum, which delivers cool air.
Reliant Energy offers what it calls Home Energy Checkups to residential customers free of charge to help them better understand ways to improve electricity efficiency. Air conditioning typically accounts for about two-thirds of residential electricity use during the summertime, and keeping it functioning properly can be a critical part of a lower bill.
In a checkup, energy auditors spend about an hour scanning the house with infrared cameras, which measure relative temperatures for air vents, doors and windows throughout the home and attic. The cameras help assess the insulation levels in the walls and ceilings and measure how well the air conditioning is functioning, comparing the relative temperatures near the air vents to the rest of the room.
The camera can indicate places where heat bleeds into a house through cracks around windows and doors — deficiencies customers can fix with caulking and weather stripping, Padilla said.
Heat-blocking window coverings also can reduce the summer heat entering a house. Glass in the windows without protection in Subhlok’s home reached over 90 degrees in some locations, even though the late-morning, outside temperature was barely 80 degrees.
Window coverings such as curtains or blinds could provide a 10 percent improvement, Padilla said.
Padilla also inspected the supply ducts in the attic that circulate cooled air to living areas. While they had been sealed carefully with duct tape, Padilla found a large hole between the air conditioning components.
Its name notwithstanding, Padilla advises against using duct tape to repair such holes because it can lose its adhesive quality in summer heat.
He recommends using air duct sealant designed for the purpose and available at home improvement stores.
But Padilla liked some of what he saw in the attic: the radiant barrier, a material applied on the underside of the roof to reduce heat, was in good condition. And the duct work and ventilation system were installed properly to distribute air evenly.
“This looks really good,” Padilla said, admiring the high ceiling that provides for wider air circulation in the attic, and ridge vents at the peaks of the roof that allow hot air to escape.
Even without an audit, it’s possible to assess how well an air conditioner is functioning by checking for temperature differentials. The temperature at the vent should be 15 to 20 degrees cooler than the ambient air in the room.
“If you are not getting 15 to 20 degrees colder, you are not going to be staying comfortable in this room,” said Pat Hammond, a spokeswoman for Reliant Energy.
Another warning sign is an air conditioner that is always running.
The Home Energy Checkup is the kind of service retailers offer to foster loyalty from customers in Texas’ competitive electricity market.
“Our experience is that when they engage with us like this, they are more likely to become customers for life,” said Elizabeth Killinger, president of Reliant Energy, which says it is the Houston area’s largest electric retailer. “The feedback that we get from our customers is that they love how much smarter they are after having an energy review, because they know what to look for, what normal looks like.”
Subhlok is not planning to rush out and buy curtains for his remaining windows but will follow up on the air conditioning problems.
“I am definitely going to have the AC and the ducts checked out and try to get a professional to diagnose if it is just the leaks or if there is a bigger problem,” Subhlok said. “I am going to get the AC situation resolved one way or another.”