Whirlybird vs. power vent — which is better?

It depends on the roof — but here’s how we think about it.

Whirlybirds are our first preference in most residential applications. They’re passive, they have no operating cost, they require no electricity, and a single Lomanco turbine moves as much air as five box vents. For a well-configured roof with adequate intake ventilation, passive exhaust is almost always the right answer.

Power vents earn their place when passive ventilation can’t do the job. If a roof’s architecture limits how many passive vents can be installed, or if code requires a ventilation volume that passive venting alone can’t achieve, a power vent with both a thermostat and humidistat is the right tool. In Montana, the humidistat component is particularly important — attic moisture in winter is as much of a threat as heat in summer, and a power vent that only responds to temperature misses half the problem.

What we don’t do is default to power vents because they’re easier to spec or because a homeowner has heard of them. Passive ventilation done correctly is quieter, less expensive to operate, and has no components to fail. We use active ventilation when the situation calls for it — not as a substitute for thinking through the ventilation plan.