The guy in the attic at right is one of America's most eminent energy-efficiency scientists, Jeff Christian, who has done important research at Oak Ridge National Laboratory since 1974.

Yes, that Oak Ridge National Laboratory, of Manhattan Project fame, which we're happy to report has long since branched out beyond what it calls "neutron science."

"I've been here for 36 years, and I barely know how to spell nuclear," Christian says.

Indeed, he says, at the Tennessee national laboratory, "the efficiency program is the largest single project in the energy arena, and it has been for 10 years — bigger than nuclear, coal, hydro, fossil fuels."

Christian runs some far-out energy-efficiency projects for ORNL, including three "robo houses" inhabited by automatons that mimic how real people use energy, down to leaving the refrigerator door open for as long as a teenager might to chug from a carton of milk.

He has just launched a "deep retrofit" study that aims to cut energy use by 30 to 50 percent at 10 human-inhabited houses (Sorry, you have to live near the lab to enlist.)

The Daily News got Christian on the phone the day after President Obama announced what's being called the "Cash for Caulkers" program to promote energy efficiency.

We wanted to get some tips for homeowners newly inspired to do some caulking around the house. If they wanted to attempt a shallow retrofit, we wondered, what would be the priorities?

"When I bought the last house I bought," Christian said, "the first thing I did was that I went into the basement and went into the attic and spent a Saturday morning just meticulously caulking every penetration: every electric wire, every vent pipe, every cable.

"I did the attic hatch as well," he said. (At ORNL, insulating attic hatches is something of a religion because the typical plywood hatch lets so much heat escape that it might as well be a hole in the ceiling.)

The illustration here shows some key intrusions for homeowners to "air-seal" — as crawling around with caulk gun in hand is known in the biz.

It also points to some helpful online resources, including an "attic access" data sheet from the Oak Ridge boys with instructions for literally battening your hatch.

Happy caulking!