I just bought a newly built home (constructed in 2025) and I'm considering installing a whole house fan, similar to one I had in my previous place. However, when I checked the attic, I noticed some differences that concerned me. Instead of insulation sitting on top of the ceiling drywall, the underside of the roof is covered in a yellow spray foam insulation. Also, it was really dark up there, indicating there might not be much outdoor ventilation. Is this a part of some new energy-efficient design? I've seen other new homes with whole house fans, but mine came with an HRV (Heat Recovery Ventilator) that's supposed to run continuously to refresh the air because the home is so airtight. I'm curious if anyone understands this newer HVAC setup and whether a whole house fan would even work in my situation. I plan on consulting with an HVAC company, but I'm wary of them just pushing for a whole house fan installation without considering my home's setup.
2 Answers
You can technically use a whole house fan in a modern, tightly built home with an unvented attic, but it would need to be ducted directly to the outside for it to work correctly. Have a look at brands like Fantech. Just keep in mind that using an HRV won’t provide the same airflow capacity as a whole house fan.
What you’re describing sounds like a "hot roof" design, which is meant to keep the attic space conditioned and can be difficult for a whole house fan. A whole house fan usually pulls in outside air, which would contradict the idea of a sealed or conditioned attic setup. You might want to stick with window fans for ventilation in this case.