Ask 19-year-old Lana Little why she spends eight hours a day hammering, drilling and otherwise helping to build an energy-efficient house for a low-income stranger and she grins with pride. ââ?¬Å?What we’re doing here ââ?¬â? people who never owned a house before ââ?¬â? they’re gonna have a house,ââ?¬Â she says.