[1]: https://www.berbel.de/dunstabzuege/zubehoer/abluft-zubehoer/...

[1] https://www.ventilatieshop.com/terugslagklep-in-ventilatieka...

Opening and closing, means you get the best of both worlds.

i think the modern cooking extractors are all built into the countertops and just filter the air. at least thats the trend in germany

Heat recovery from an extractor (eg remove heat from air before expelling) would achieve the goal the rating is aimed at, without compromising indoor air quality by not having a way to remove humidity. Or maybe another kind of integrated dehumidifier that discharges in your sink/plumbing maybe.

Those filter-only extractors won't do for anyone serious about indoor air quality.

It's possible to install dampers that are normally closed for airtightness, but open when the kitchen vent is activated (both on the exhaust, and makeup air, side of things):

* https://www.greenbuildingadvisor.com/article/makeup-air-for-...

Even the Passive House folks are fine with this arrangement (§3.4):

> When the exhaust air system is not operating the exhaust air and intake air vents should close airtight and should not cause any leakage volume flow. Furthermore, additional insulation will be advantageous at these locations.

* https://passiv.de/downloads/05_extractor_hoods_guideline.pdf

So I'm not sure why your building codes mandate recirculation, since I'm guessing even they wouldn't be as "strict" as the PH folks.

EDIT: it looks like the terms are 'Prescriptive' and 'Performance'. e.g. https://www.energycodes.gov/sites/default/files/2019-09/Ener...

It's also more directly meaningful to customers. An A+++++ mansion is going to use more energy to heat than a modest A+++ house.

Because numbers require everyone who is involved in comparing options (i.e. consudmers) to have intimate knowledge of what those numbers mean. Is X kwh actually good? How does it compare to other houses in the area? What number do you use - the amount of energy it will take to heat the house, or the amount of energy of a specific type you will use. How do you compare those (a house with Natural Gas as a heat source will require significantly less electricity to heat than a house with electric radiators, but will likely _cost_ more).

Using ratings gives a standardised way to compare them. If you compare two houses, one has an A rating and one has a B rating, the B one is strictly worse, by an amount that someone who knows something about this has deemed significant.

> That's what appliances do

Appliances are graded on a similar score here. Every appliance you buy in the EU has one of these [0] labels (which has the same problem).

> An A+++++ mansion is going to use more energy to heat than a modest A+++ house.

You're comparing two different things here, and forgetting a very important point - someone who is going to buy a "mansion" is not going to buy a modest house, so it doesn't matter what the rating of the house is in comparison. What matters is the rating of the mansion next door.

[0] https://en.wikipedia.org/wiki/European_Union_energy_label

It even shows the average cost of other similar products. So you can see both the absolute numbers and a visual representation of how efficient something is in relative terms without having to squint and count '+' marks.

I don't see why we couldn't do that for houses. Maybe use a unit like BTU instead of kwh to account for different heating sources. And include a comparison to the average range for houses in the area.

This would be a lot more concrete and avoid arbitrary ratings. If the ratings are based on bureaucratic rules (i.e. can't have stovetop vents) instead of actual measurements, then it feels a lot less meaningful. "This house will cost about $X to heat each year" is a much more useful piece of information for someone house shopping.

[1] https://www.sce.com/residential/home-energy-guide/energy-sta...