MADISON, Maine — The machines are humming again at the old paper mill in Madison. …But unlike the days of giant paper machines, there are no harsh chemicals in use, no smell permeating the mill, and seemingly little leftover waste. Instead, TimberHP is producing building insulation, made from wood chips. Matt O’Malia, one of the co-founders and Josh Henry began working on the project eight years ago, looking for what they consider a better way to insulate buildings, with a product that is renewable, recyclable, and what they see as carbon-negative. And one where the raw materials come from Maine and are processed into the finished product here as well. O’Malia, an architect who specializes in energy-efficient buildings, and Henry, a chemist, teamed up to develop a building insulation alternative to foam, fiberglass, and mineral wool—the most commonly used materials. They found it in Europe.