In 1900, when the student residence at 24 Fountain Avenue was built, heating oil was cheap. Insulation wasn’t a concern. Window sealant didn’t exist. Hot water gushed from the shower heads. “We call homes like this ‘balloon framed,”’ explains Gary Rawlings, lead energy auditor technician for Wesleyan’s contractor Lantern Energy. “Air from the basement flows up through the walls and escapes through the window frames, the area around plumbing pipes, doors, and attic. In this particular house, there’s a big gap around the air duct. That’s never a good sign when you can see down into the basement.” The 24…