Amazing, I've never even heard of a ERU in residential work. I'm not an engineer so I'm unaware of the rules and regulations, I'm just pointing out what I've actually seen getting installed and what engineers sequences say about it.
Green Building Advisor (https://www.greenbuildingadvisor.com) is a great community for such things, with a 99% residential focus.
I have an ERV in my house, running continuously. There are some great pieces of equipment out there, but they require conscious consumers and/or progressive code enforcement to end up in use.