Energy efficient with tight seals is somewhat antagonistic to high BTU gas cooking where removing all the effluent is far more important to one's health than saving some energy. (If thermal efficiency and reduced effluent is important, the cooktop should be induction type.) To get away with 400 CFM would require using a 30-inch induction range with no hot oil/grease cooking.

What you will need to capture plumes for your 48-inch Wolf is a hood that is at least 4.5 ft x 2 ft, and that will be marginal.

Nine square feet requires, assuming gas cooking with high oil and/or grease temperatures at times, 90 ft/min air flow into the hood entry aperture. This alone leads to 9 x 90 = 810 CFM. Then there are the pressure losses vs. the blower fan curve leading to a rated blower air flow rate of 1200 CFM. The MUA has to supply 810 CFM or whatever it turns out to be with a low differential pressure between interior and exterior. How low depends on whether the kitchen air connects to the supply air of any combustion appliances (other than the range).

What @opaone found is that with a large (and tall, mind) commercial hood, the specific air velocity could be lower, and hence a hood with a 30-inch front to back depth, but very large containment volume (reservoir below the baffles -- different than a Wolf Pro hood) could get away with a generally lower CFM per square foot than otherwise needed by residential design hoods. I doubt, however, that 400 CFM (and that is likely to be rated and not actual) would be adequate for wok cooking or steak searing. I'll let opaone regale you with his estimated actual flow rate he has observed to be needed for various cooking processes.

In summary, if you want to use you 48-inch Wolf range as it was intended, a wimpy CFM value won't be suitable. You would end up with a room full of smoke and grease soon to condense to a film on walls, draperies and furniture. An added benefit will be a long term odor memory of your great meal.

A tightly sealed house also needs a heat or energy recovery ventilation system. I think you can benefit from more broadly experienced hvac pros.

I would throw my experience into the ring.
I cook daily, multiple cuisines. I had a 30 inch gas range with a 300 CFM hood. It did nothing.
I'm paying significantly more to upgrade my kitchen in my new production build to get a 600 CFM hood, which requires makeup air.
To me? Worth every penny, and if I could get higher CFM I would (limited by production builder).
Don't buy a 48" range of you don't want to vent it properly. Wolf has a handy ventilation guide that will tell you the ventilation you need, and it's not 400 CFM.

We have a 30" Bluestar gas range and a 1200 CFM Modernaire hood with extra large front-to-back capture area. It works amazingly well. No cooking smells in our open floor plan kitchen. But I do need to regularly run it at full power, especially when stir frying and making more fragrant foods. Judging by the amount of oil that I remove from the baffles on a regular basis, I don't think I would want to go much lower in power if your design philosophy is form-follows-function.

On the other hand, not everybody cooks as frequently and as elaborately as our family. And some households prefer a "show kitchen". That's fine. No judgement. In that case, reduced CFM might be OK.

But independent of what I said already, I agree with previous comments that I would not recommend a gas range in a tightly sealed building unless you make sure to have adequate make-up air. That sounds like a disaster waiting to happen. All that extra moisture in the air is bound to cause problems.

"our HVAC/architect team wants us to keep the range hood under 400 CFM because of the make-up air issue."

This is quite irresponsible of them unless the 48" range will be only for show, not connected and so never used. That they would suggest this raises serious concerns about their knowledge of indoor air quality, performance of wall & roof structures (particularly dew point/moisture mgmt), and other bits so this may be minor compared to other problems you may face with them.

Kitchen range ventilation is pretty straight forward; 1) determine what you need based on what effluent will be produced, 2) design capture & exhaust system, 3) design make up air system to match.

If you want to do this backwards, starting with No MUA, then you'll need to determine what range will work with your cooking style and need only 400 CFM or less. That's likely going to be a small induction range depending on how well sealed your house is.

What is "energy efficient with tight seals"? This is quite nebulous. Will your house be 0.65 ACH50? 0.9? 1.0? 1.2? 1.8? 2.0? Where is this (near what city and so what environment)? To me energy efficient with tight seals is 0.9 ACH50 or below. Some builders advertise that their 2.0 ACH50 house is 'energy efficient'. (Though what you really want to know is how much total air can be easily pulled in through leaks in the envelope so better to know CFM50/SqFtEnvelope)

Personally, given what I've learned, I'd not want ANY air being pulled in through wall cavities and other penetrations that could create moisture and mold problems in the structure and contaminate indoor air with whatever is in the wall cavities and so gets pulled in to the house so, depending on the size of the house, I'd do powered MUA for anything over about 200 CFM, but that's another topic.

Get an OTR microwave, they have 400 CFM.

LOL!

While I fully agree w/ @User sentiments, the numbers are a bit of an exageration in most cases. $4k for the gas line is more typically going to be less than $1k, Our heated and dehumidified MUA to support our commercial hood was less than 1/3 the $7k quoted, ...

Yes, there are a lot of below the surface dry and boring costs and in some remodels these may be quite expensive and possibly as expensive as mentioned but those numbers are closer to worst-case scenarios rather than typical.

Each project is different as are the knowledge and abilities of different remodelers. Homeowners should get quotes for THEIR project and not be scared off by worst case scenarios.

Thanks for the schooling, everyone. It sounds like the directions we should look into are 1) How hard would a makeup air system be, really? and 2) Are there lower BTU 48" range tops? We're pretty married to a large number of burners and gas, but it doesn't have to be that high powered.

I don't know what standard they're trying to keep with the tight seals. We're in VA. We're used to never using a hood (because of the noise issue + ignorance about health concerns) and so anything that reduces smells and grease film build up will be a big step forward from zero.

It is the temperature of the pan surface, plus the gas combustion products, that determine the velocity of hood air needed for containment of that part of the plume that is captured. You can lower need by a smaller hood, but only with a smaller cooktop area.

In any case, besides the questionable value of perfect sealing, what combustion appliances do you intend to have, and where are they located relative to air paths to the kitchen?

Makeup air isn't hard if you plan for it and have people who know what they're doing, especially in a new build. It sounds like maybe your HVAC team doesn't - so instead is trying to steer you away from it altogether.

48" cooktops are almost by definition high end appliances with high BTU burners that require large CFM hoods (unless you're just using it for show and not cooking on it). You could get an AGA 48" induction range, which might lessen the required CFM, but it won't get you below 400. And even if it were "OK", I wouldn't want a 400 CFM hood, because it wouldn't be enough to capture grease etc. I also would question what kind of cooking you're doing that you'd need 8 burners but none of them need to be high powered.

I also would question what kind of cooking you're doing that you'd need 8 burners but none of them need to be high powered.

Oh, that's easy. It's the Oompa Loompas. They only ever need to melt chocolate, but they need gallons worth of it :-)

Seriously though, listen to what everybody else is saying here and get a hood that is properly sized for your kitchen. You'll be much happier with the results. It sucks having grease all over the cabinets and smelling yesterday's meal in the morning -- and that's ignoring all the longterm health issues and the vapor damage to the house.

MUA is a bit of an extra complication, but so is any another part of infrastructure that your house needs. If your contractor can't figure out how to handle that requirement I wonder what other things they don't know how to do.

I really don't think it is that uncommon for HVAC pros to not be well versed in effective MUA needs. We see it all the time on this forum, many are just inexperienced with true needs and inspectors don't always push it. (I passed inspection with a 1200 cfm hood and no MUA, which was put in after).

Seeing how dismissive my contractor and HVAC guys were of MUA, I reached out to my longtime HVAC guy and asked if he was up to learning and doing something new. Fortunately he had experience with restaurants and the manufacturer of my MUA system (Fantech) also provided great tech support. I was incredibly fortunate that a good configuration, with heated MUA could be installed after the renovation was done. I mean very very lucky. If not for this forum, I would've just accepted whatever my contractor said.

It also depends a lot on regional differences. If I recall correctly, California is one of the unusual states that doesn't ever require MUA. So, not surprisingly, contractors aren't familiar with it.

And honestly, it makes sense. We have windows that stay open year round and provide plenty of make up air. But that wouldn't work in other climate zones. And that doesn't necessarily address concerns about back drafting; that needs to be decided on a case by case basis

CA does require MUA. The IRC is the basis for all state and municipal codes there. But because lots of municipalities take the IRC and tinker with it, and add a whole bunch of more restrictive amendments, ”the codes” can be really confusing to not just homeowners, but also contractors trying to do the right thing. It’s just one of the reasons I left there as a 22 year old, and never looked back. Love to visit! But to operate a legit business there without a huge overhead is impossible.

@kaseki and @opaone will give you all the technical and practical reasons to have an adequate range hood for your range. But from experience, I'll tell you that having a downdraft or OTR recirculating or basically any underpowered range hood means wiping grease off ceiling, walls, nearby cabinets, lingering smells, combustion fumes, steam damage, and cleaning, cleaning, cleaning. Don't even think about it.

Yes, it's loud, but not for long. I can tell within 15 seconds from the next room if someone forgets to turn ours on after a burner on our Wolf range is ignited. I don't generally have a great sense of smell, but THAT I smell instantly.

Interesting you would say that about California. We directly asked our building inspector and he told us that MUA wasn't required.

Keep in mind that:

U.S. code is about 8-14 years behind many other developed countries and they are a bit behind science.

U.S. code once allowed exposed asbestos, lead paint and many other harmful components that we'd not dare want in our houses today.

Physics and the health impact of harmful PM & VOC's are the same in every state and every municipality regardless of what code or code inspectors say.

YOU are responsible for your health and that of people who live in your house or visit. Unfortunately your builder, HVAC contractor, interior designer and kitchen designer are unlikely to be knowledgable on this stuff.

Thank you for looking to that document. That's certainly informative, and it's said to see how my building inspector gave me the wrong impression. And it sounds as if I'm not the only one, as I have heard other Houzz members make similar comments.

But I also noticed that instead of having a firm rule about 400CFM, that document is a lot more detailed and is concerned about the envelope of the house and then other appliances. In our case, we'd actually be fine. So that's good to

@M can you tell me what Modernaire hood you have? Is your motor internal, inline, or external. Thanks.

I would have loved an external motor, but no matter what we tried it simply wouldn't have fit into the available space. The only place to vent was on the roof where a roof deck is taking up a lot of the available space.

We picked the PS16 and increased the dimensions to 30"×36". It has a 1200 CFM blower and 10" ducts. We mounted if above head height, which is very convenient to use as I hate things the interfere with my sightlines.

With respect to M's system, the flow rate I would argue would be needed for most energetic cooking would be 90 ft/min times 7.5 sq. ft = 675 actual CFM. A 1200 CFM rated blower should easily achieve this, and do so in most circumstances at less than maximum power. This reduces noise, and may make up for M being forced to use an in-hood blower instead of a roof blower with intermediate silencer.

Larger and higher is OK so long as cross drafts are modest. Otherwise, the hood has to increase further to accommodate the offset in plume shape. (Recall tornado images where there is a lot of lean.)

Yes, we don't regularly need to run it at full speed. It has a continuous speed control and most of the time we run it either on low (for less challenging foods) or at 80% (for stir frying). But there are times when we need to go to full power. For the most part, this hood is pretty good and I am quite happy with the trade-offs that we made. But as with most residential designs, capture volume is small compared to commercial hoods, and I honestly doubt that it gets the full 1200 CFM. We have an old leaky house and several windows on that floor that are open year round. So, no active MUA, but plenty of air from all over the place.

Nonetheless, having a (nominally) more powerful blower gives me a little more slack to make up for some of the known trade-offs. This hood replaced an old VentAHood and the difference is like night and day. No more cooking smells, ever. The downside is that I now need to clean the hood more frequently. I am always amazed just how much oil/grease it captures in such a short amount of time. Fortunately, cleaning is pretty easy with baffled hoods.

The cooking area is very well protected from most cross drafts, so I am happy with our choice of mounting the hood higher up, and then increasing the overall size. It makes for a very functional design. Not everybody will have this option, but it's nice that ModernAire always builds to order. So, customizations are easy to do.

Marty Weiner I'm just starting to research hoods... again. I didn't research enough the first time, so we're paying the price! Our 1200 cfm hood is just too loud. And we need to add make-up air, our contractor claimed we didn't need it for our 48" gas range! Have you purchased a hood yet? If so, what do you get and how do you like it? Thanks! I'm in VA too, btw.