The most screwed up, badly designed, inappropriately used appliance in your home: the kitchen exhaust
As part of its Future of Home Living, PSFK shows the GreenHood from Italian glam-kitchen designer Snaidero and appliance-maker Falmec. They say it " helps eliminates odors while sanitizing the air around it, using a technology similar to what’s found in ionizing air-purifiers….the always ‘on’ hood acts in eliminating odors and pollutants from organic molecules suspended in the air like cigarette smoke and smells from cleaning supplies."
It is a ductless recirculating hood, a type usually thought of as little more than noise-makers, or as Dr. Brett Singer calls them in the New York Times, "forehead greasers." The article in the Times, entitled The Kitchen as a Pollution Hazard, lists some of the chemicals that are emitted while at home on the range:
Frying, grilling or toasting foods with gas and electric appliances creates particulate matter, nitrogen dioxide, carbon monoxide and carbon dioxide, and volatile organic compounds….Emissions of nitrogen dioxide in homes with gas stoves exceed the Environmental Protection Agency’s definition of clean air in an estimated 55 percent to 70 percent of those homes, according to one model; a quarter of them have air quality worse than the worst recorded smog (nitrogen dioxide) event in London.
Snaidero doesn't explain how their recirculating hood somehow makes carbon monoxide and nitrogen dioxide disappear. Nor do they mention how much air a fan mounted over a kitchen island has to move to get it to actually reach its magic filters, but it is a lot.
Spend some time on Pinterest and you see this again and again: fashionable foodies continue to build giant commercial gas ranges into islands and put almost useless freestanding hoods over them, or buy the even more useless downdraft units.
Yet as our homes get built to higher performance standards, they are getting tighter, and proper ventilation and exhaust is even more important. That's why everyone should have a decent exhaust hood against a wall, venting to the outside. But what goes out is only half the story.
Engineer Robert Bean at Healthy Heating describes the common problem: People go out and buy the big Wolf or Viking stove, stick the big hood on top and don't consider how much air is being sucked out. However, the air going up the hood has to be replaced with something. He writes:
In my opinion the potential health and building problems created by hood induced negative building pressures should rest squarely on the appliance manufacturers and their dealer’s shoulders. The HVAC industry needs to step up and tell these range hood vendors that when you continuously suck way more than you blow you’re going to create problems for the occupants and the building - full stop.
Since it is inside your home, that air has to be heated in winter or cooled in summer, and that is a huge amount of air.
Putting this into perspective - with that amount of output you could heat a floor space over 10 times that of the kitchen it is serving. If you did the same exercise but for summer time sensible and latent cooling you would likely find a similar load for dehumidification of incoming outdoor air. How many people would put in for giggles a 10 ton cooling plant just to wring out the moisture from the make-up air in a residence?
The bigger the range, the bigger the hood, the bigger the makeup air unit required, the more energy needed to condition the makeup air. Don't even think about putting it all on an island, because it has to suck even more air to work at all. And if you really care about being green in the kitchen, forget the Viking and the Aga and go induction.