When the star Sirius appears in the night sky, it officially kicks off the "dog days of summer," the hottest, stickiest days of the year _ from July 3rd to August 15th. Now is an excellent time to prepare to beat the heat -- and to beat high energy bills -- by purchasing a new air-conditioning system. Today's high-efficiency models with a federal "energy-star" designation use half the energy a 20-year-old model uses. During peak cooling periods, you can cut overall energy bills 20 percent to 40 percent. Ten-year-old-or-older units have seasonal energy efficiency ratings (SEERs) of only 6 to 8. New units are rated 12 or greater _ a big difference that leads to big savings. Also, many utilities now offer rebates on these units. And that's the On The House tip for today.