Our dining hall project is considering using ESP filtration technology in the kitchen vent hoods.
Manufacturers claim these units:
1) save energy
2) reduce maintenance
3) produce exhaust air so pure it can be sent directly back into the building as recovery air (assuming electric appliances, so no carbon monoxide).

Does anyone have any experience using this technology? Does it really save energy, from a LEED standpoint? How does it match up to the manufacturer's claims?
Thanks!