Three ways to ventilate

No matter how diligent you are about source control, “residual contaminants like dust, pollen, and VOCs will find their way in,” says Rashkin. Cracking a window lets in fresh air but also wastes energy and can introduce outdoor pollutants such as smog. That’s why mechanical ventilation is so important.

Back in 2004, plumbing and heating expert Richard Trethewey learned this the hard way when from radiant heating to an ice and water shield. “But like the shoemaker’s kids, I didn’t put in enough mechanical ventilation,” he says now. “I thought, ” He didn’t take into account that he was often on the road for long stretches. “We’d come home and the air would be stale. You could smell whatever we’d made to eat the week prior,” Richard recalls. He ended up putting in a whole-house ERV after construction was complete—at a significantly higher cost. “Now the air is clean, and there’s incredible thermal comfort. I’ll never live in a house without a fresh air system again.”