Reddit mentions of M-D Building Products Available 3822 Vinyl Garage Door Top and Sides Seal, 30 Feet, White

comes in swinging...or stripping, not sure

Eyyyyyyyyyyyyyyy! One piece doors suck. I have one and I hate it. Only reason I still have it is because my framing was an old carport and not up to code sooooo, what to do what to do.

This stuff may be your best bet. Secure it to the garage with glue or maybe sheet metal screws.

I was going to suggest This typical vinyl, but it wont work properly unless you attach it a way it's not typical application

Also, I'm I'm seeing that post correctly, you most likely will need to move it. Door appears to be 7' high, and if that's an actual 7' rail, your sectional wont fully open(guess would be 5ish feet). If you have more ceiling space on the other side of that beam, you could look into a high lift system. If you want it automated you could also look into a Jack shaft operator.

I'm a professional mechanical engineer and a Certified Energy Auditor per the AEE.

Here's a couple things I did for my house that helped. They might help you.

Weatherize the garage: Add a floor threshold to the garage. Best done in the summer. Replace the weather seal on the top and sides. Replace the garage door threshold. All Amazon links. Measure your door and get the correct dimensions. I just linked to general items.

Weatherize your outlets and light switches: All holes through the wall allow tempered air to leak out. (nice warm air in the winter, nice cool air in the summer). With a flathead screwdriver, you can add gasket seals to all of your switches and outlets to reduce air leakage.

Weatherize doors and windows: If there are doors and windows that you don't use often, or don't use for a season, seal them off. If you use a door more frequently, there's lots of draft dodgers to help seal the door. Growing up, if it got super cold, we'd take a spare down comforter and nail it to the wall, totally covering the door.

As far as thermostats go, changing out the thermostat to a wifi thermostat and/or a programmable thermostat will go a long ways towards energy savings. Nest is definitely the best thermostat out there, but I recognize that it's the most expensive. In my opinion, the Nest is the best one because it has the best developed home/away sensors, has a clean and slick easy-to-use app (even for 8 thermostats like you'd have), and easiest to use scheduler. Don't change just one thermostat. Change all of them. At the very least, change the thermostat to a programmable one.

In general, it would help to go through the weatherproofing page of Amazon and buy and install anything that applies to your home and apartment.

As far as capital equipment, replacing boilers with condensing boilers can help, but remember that condensing boilers provide the most savings at the temperature extremes. during shoulder seasons. Consult a local professional mechanical engineer to determine if they will really benefit your location.

edit: had a brain fart when i wrote this. condensing boilers provide the most savings at the shoulder seasons. take a place like Fairbanks, AK, which, aside from this winter, generally spends most of the winter at the design outdoor temperature of -40. a condensing boiler operating at the design limit doesn't provide any more savings than a "standard" 80% AFUE efficient boiler. just doing my part to avoid spreading misinformation on the internet.