Beloved by builders, scorned by building scientists, and largely ignored by homeowners, recirculating hoods have a mixed reception. They do not require a wall penetration. They will not cause house depressurization. Some of the scientific testing shows them to be near useless in their current format but they could be a reasonable alternative to vented hoods if designed properly and maintained diligently. Is that asking too much?
Is there anyone out there with positive experiences with recirculation hoods (especially if it is supported by data)? Has anyone seen a recirculation hood design that is intrinsically superior? Or should we just continue the current advice to avoid these devices in favor of vented range hoods?
CO isn't adsorbed by activated charcoal filters. There are other compounds that result while cooking - even on electric stoves - and I don't know anyone that has done extensive testing of food groups and which emissions are captured. The more you cook - the more frequently the filters need to be changed. A set of three or four charcoal filters for a stove hood can cost $10. Manufacturers often suggest replacing the filters every several months -- which means that it could cost $40/yr in filter replacement. Is that less or more than the equivalent energy cost if the air is vented outdoors? No idea. But I do know that the hoods do not generally have a means to detect a filter that is depleted. Most the activated charcoal filters are really just capturing some of the grease and aromatic chemicals - perhaps providing a false sense of effectiveness.
Of course the effectiveness of that filter presumes also that you're really capturing all of the cooking fumes that are rising from the skillet. LBNL and others have shown that capture range is a problem with a lot of hoods.
I'd suggest perhaps capturing some "cooking fumes" and doing a spectroscopy analysis of the stuff in the fumes - then look at how well an activated charcoal filter actually captures that bad stuff is a good step in the research.