First, the contractor needs to do a Manual J heat gain / loss calc to determine proper system sizing. Depending on your utility rates (I think you have cheap electric in Washington State), you can get a heat pump for primary heating, and a gas furnace as auxiliary heat (back-up heat). The heat pump doubles as a central a/c unit for summertime cooling. This "dual-fuel" system also provides choices for you if the cost of one of the fuels (gas or electric) rises dramatically in the future. FYI: the gas furnace would be located inside the air handler if it is a forced-air system (no radiators or baseboards). You make it sound like the air handler and furnace are separate now. If you have ductwork in the attic, it is critical that it is checked for leaks (and proper sizing as well). I would recommend that you get several quotes and not just go with Mr Lennox. The more quotes you get, the more you see the range in pricing between contractors. Good luck.

We "built" the house we live in now, tract home in new neighborhood, with some customization. House conversations with friends and neighbors always have regrets in there. Bump-outs, boneheaded designs we should have caught, upgrades that should have been made, upgrades that aren't worth it... the list goes on. Based on our experiences here, I already know there will be design / decor issues that will have D'oh! moments. It's impossible to think about EVERYthing. I think we've hit all the major points, and have enough flexibility to change in the future. Our lives changed quite a bit in the 6 years since building (the once large pantry is now crammed because I now do the majority of grocery shopping at Costco and that not change for at least 15 years for example). I can't see into the future, but we learned from this build, and kept the evolution of our family in mind with our design. 1) The architect/draftsman is only as good as the information provided. They don't know us, or live our lives, ( I wonder if there'd be a benefit to having separate design consultations with the clients, much like relationship counseling, to get a really clear picture, lol), which is why we rely on their education and expertise. 2) The reason copy editors exist: to catch the technical mistakes writers make, and can no longer "see" due to closeness to the project. Same reason med errors occur. I think when we originally like a design, then look at it, dream about it, obsess over it, we can't "see" the flaws or potential problems that others might. Hence all the floor plan critique posts here. I think too, that online and builder plans lull us into a false sense of security- "they design and build houses all the time, they're experts, hundreds of people have bought the design, what could go wrong?!" We found that customizing our builders plan threw them for a loop, and didn't realize it would do so, until after the house was built, and weird things weren't right; towel bar location, depth o linen closet, outlets, etc. 3) We are often playing on tilt. We're all living SOMEwhere, right now, and designing a new place to live, with many features that we love (or would love to have) or without the ones we loathe, those HTOD, that we obsess over in our current or past homes. Finally, the same way any artist of any medium does, we aren't always satisfied with the end result of a project. Sometimes you just have to be DONE, even if to your artists eye, you could have kept going. Having said all that, I know there's going to be some regrets, but hopefully -I believe- the joy will outweigh them!

So, your double pane U-Factor appears to be a 0.27. Good, but what about that "will add thermal performance that far exceeds the vinyl options". I am quoting you directly from above about 6 posts ago. There are more than a handful of vinyl windows that will best that thermal performance in the case of double pane and more than a handful that equal or best the thermal performance numbers that you show in triple pane. To be certain, 0.15 is a good U-Factor, but it is only equivalent in this case to just the handful of vinyl windows that I know of personally not to mention the more exotics that are designed solely around performance. I do love nice wood windows, but to claim they are more efficient because of the wood is sketchy science to put it mildly.

Home depot, cut to fit right in the store ( width ) , inside or outside mount. Great looking......and you could take a year to decide what you want. Light filtering or black out, I've used them as a "permanent" in plenty of summer homes. kids rooms: ) and in just finished remodels waiting for the real thing to arrive. They're great. Not EVERY window in a home needs cover. ...... Bedrooms, baths, where you watch tv. are the bulk of it. Some need privacy only, others black out. These are best of all worlds and no.....the length won't matter if longer than the window. You'll get a nice clean, neat and tidy look and buy LOTS of time_ with the look of perfect fit as you wait. https://www.homedepot.com/p/Home-Decorators-Collection-Snow-Drift-Cordless-Light-Filtering-Cellular-Shade-35-in-W-x-48-in-L-10793478630233/202587002