Proper means of ACH

MacPHJr

The town in which we are bidding a project requires the renovation/addition have an ACH of .35 by a mechanical ventilating system. This is being enforced for the town's board of health. What is the proper way to achieve the .35 ACH?

Tim P._3

Ah yes.. mechanical ventilation

..because people can't be trusted to open windows.



I have seen the bathroom fans put on automatic timers.  The air exhausted is replaced by infiltration.



Or, you can use a HRV.

MacPHJr

Basement Renovation

This will be a basement renovation with only two small windows and no bathrooms. Its going to be a home theater.

Mark Eatherton

Exhaust fan...

Calculate the volume of the room, and multiply times .35, then find an exhaust fan that can move that many CFM;s to meet their needs.



If you have a lot of watts going into this room, you may need to ventilate it to keep it decent anyway.



In your heat loss calculations for this space, yo may already be providing adequate ACH just through normal infiltration, and may not need any additional mechanical air changes, but if you do, just make up the difference..



ME

MacPHJr

Thanks for the advice

Thank you both for the advice. I have been told that an ERV would work as well, especially with wintertime humidity, but on the other hand we are in the Boston area and a HRV seems more appropriate. Any advice on what type of unit to use?

Mark Eatherton

I've been told..

That the difference is in transferring humidity. If humidity control is important, ERV, if not, HRV.



Both require regular maintenance (filter changes).



ME