OK, youall have succeeded in drawing me into another argument. Let's start with the purpose of the overhead vent. The vent is intended to capture and contain effluent contained in the rising and expanding cooking plumes. It has an overlap capture requirement that depends on height, and a flow rate containment requirement that derives from plume velocities and secondary factors. It is not for capture or blockage of grease splatter, as that could require enormous air velocities to achieve. Down-draft "venting" and pop-up side-draft "venting" cannot achieve the needed capture and containment provided by an overhead hood of proper specification for these reasons: Air flow velocity drops rapidly as a function of the smallest dimension of a slot air intake (see the 2003 ASHRAE HANDBOOK, HVAC Applications, Fig. 6). The air velocity in all cases is too low to significantly change hot cooking plume momenta except those plume portions close to the pop-up, so the overhead hood depends on the natural rise of the plumes. Deviation of the upward momentum to the side, or by 180 degrees to head downward, can only work if the plume has low momentum, as in steam from boiling water. Hot oil/grease/moisture plumes from wok cooking and searing will be poorly deviated sideways or in reverse. Fume hoods can have horizontal hood configurations, but the top and sides are blocked from allowing fumes to leak out. The turbulence issue is complicated. Up-rising plumes can be disturbed by side drafts, poor insertion of make-up air into the kitchen, and cook motion. Side-drafts will be pulling air across pan and pot clutter, so some added turbulence is possible, but I don't think it will be a significant addition except close to the pop-up due to the velocity fall-off introduced above. On the other hand, a pop-up can block splatter trajectories from the burner up the the angle between pan and the top of the pop-up and as far as the pop-up sides shadow the area beyond. For this function, no air flow is needed and much of the pop-up system hardware can be dispensed with. If a blank face is used (no vent holes/slots), cleaning may be greatly simplified. Underfloor ducting, blower, external cap can all be deleted. Some cabinet space for the elevation mechanism has to be sacrificed. While a pop-up splatter blocker is a good idea if the degree of blockage is deemed sufficient for the expense, the subject raises the question of why children are sitting in range of hot grease splatter. At a minimum they would need eye protection. There are requirements (that I don't have at hand) for desirable rises and/or runs of seating countertops connected to cooking surfaces. I recommend proper desks in quiet areas for studying. The student should be fully absorbed into the material to be studied without distraction (or at least as little distraction as a post pubertal youth can manage).

You're welcome. Can you put a lower counter below the one window on the left wall? If it's the right height for a baking counter, say 33", that would make a nice baking center for you. If that's possible, here's another idea. Move the DO to the lower end of the left wall with a pantry cab between it and the wall. Then add a lower counter below the window, spanning the distance between DO cabs and cabs on upper side of the left wall. Then turn the island perpendicular to its present position and shift it over to give you enough aisle space between perimeter cabs and island. Rhome has only 36" between prep area and cooktop and it works for her but most prefer 42". This eliminates the butt to butt problem of sink, DW and cooktop. On the backside of the island, go with a raised curved counter with seating facing the baking center. This eliminates the in-a-row seating that makes conversation harder and also provids a buffer between seaters and cooktop activity (a pop-up downdraft helps with that, too). These changes mean that fridge traffic no longer crosses the work zones so you can eliminate the undercabinet fridge. You can increase to a 36" fridge if you need more room. Oh, one thing just popped out at me. You wrote that you're doing standard depth fridge but your plan shows a fridge with CD dimensions. A standard depth fridge will stick out several inches more than you show. You could take the money you would have spent on a fridge and undercab fridge and get a CD fridge instead and gain more aisle space. I'm talking stand alone, not built-in. If the window doesn't allow for a 33" or 34" counter, you could still put one in front of it, just do a "floating" counter. A GWer did such a thing for her sink in an old house. Wish I could remember who it was.... It was clever and allowed her to put counter where one wouldn't think counter could go. Until I remember who it is, here's my recollection of how it works. She has cabinets up to the window sill, then open space in front of the window between lower cabs and counter. You could leave this clear or put baskets there for storage. The unfitted look would be appropriate for your old home's age. Heck, if this look works for you, you can go with standard height counters and have a really nice long counter run, perfect for baking prep.

merk, have you looked at Kobe? They are supposed to be a decent hood but at a price that is less than Zephyr. They are made in China, which is one reason for their lower cost but it seems that they are still a decent product. And I think they come with 8" venting but I'm not sure since it's been a long time since I researched them. I used to also wonder what the big deal about venting was. We didn't use our pop-up downdraft for our island cook top often because at low speeds, it really didn't remove smoke or cooking smells and at high speed, it sucked the gas flame out. Back then, cook tops didn't come with automatic re-ignition so I never knew this had happened until I smelled gas. Not good! Even on high, it still didn't remove all cooking odors and smoke. The newer pop-ups are supposed to be better - they also rise higher so that helps them fight physics (smoke rises) but even so, they aren't as good as hoods. I started to learn about the importance of proper ventilation from GW and from my friend, a CMKBD. So we bought a good hood this time and I'm so glad we did. It works so well that I've never needed to turn it above low speed. I can't smell what's cooking on my induction cook top unless I stick my nose over the pan. My hood is 600 CFM but I think I could have gotten away with 400 CFM and saved the cost of MUA. If I had stuck with gas, I'm pretty sure I would have needed 600 because gas adds combustion fumes to the mix. Oh, well. We'd already ordered our hood before we did the tear out but once I saw how much disgusting yellowed grease was on my kitchen valances, I was so happy that I had spent the money on ventilation.

@Patricia Colwell Consulting You're right I should have posted some photos of the space. There isn't much wiggle room and behind the cooktop there's only about an inch or so which isn't enough room for a pop up vent. The end goal is to replace the cooktop with either induction or gas and do as minimal reworking of the cabinets and venting as possible. Unfortunately it's not as simple as just replacing one-for-one. I wish it was! And of course, our relator told us it was simple when we bought this house. The cabinets aren't what I would choose if I was designing the kitchen but it works for now until we can redo the entire thing years down the road. These photos make the room appear quite yellow but that's just the light balance. Everything is white. The floor is more of a neutral brown. The cooktop is at the far end adjacent to the double oven. Behind that wall is the washer/dryer. Currently the GE electric cooktop has a downdraft blower built into the cooktop itself. It works great but I can't stand cooking with electric especially after having gas in our old house.