Hey Everyone!

I am working on an 20×24 ft Studio ADU build here in Oklahoma (Climate Zone 3A) and have been researching a lot on this forum and podcast and decided I should join the community! 

The current problem I am facing I could use your feedback on is determining where to place our mini split head unit, and how to handle distribution from the unit along with fresh air supply, and haven’t been able to find a lot of resources on best practices there.

Attached I have 3 options I am considering and would love some feedback on what you guys see as the pros and cons of each (or tell me what I’m not asking/thinking about that I should be!). Option 1: Best option seems to put the head unit on the center of the west wall pushing air in a general way towards the kitchen and bathroom door to distribute. Problem with Option 1: That west wall is the scenic view wall with large windows and not ideal to have the head unit above them/no room for curtains. Option 2: Next possible location would be above the bed cabinet (off to side to minimize direct blowing on bed), would go past the bathroom door and have to ‘turn’ to make it to kitchen. Problem with 2: Concerned about enough conditioning making it into the bathroom and kitchen, the exhausts would be pulling air to those corners to help, but is it enough? Do I need to add a transfer fan to bathroom and/or kitchen, or not a concern? Option 3: Go with a horizontal ducted indoor head unit in a space above the closet, run a supply to bed area, and an exposed supply duct across the bathroom upper ceiling, with a vent off the side for the bathroom and a vent at the end for living/kitchen. Problem with 3: More expensive, and need to figure out if I can even fit the unit, and return/supply ducts in that space. Know the tight 90’s for return are not ideal. Additional Info: The ADU is being built with SIP Panels (4.5″ walls, 6″roof), 8′ walls, with a vaulted ceiling with 4/12 slope for average ceiling height of 9.67′ I ran a preliminary Manual J with CoolCalc that has this ADU at a little over 8,000 BTUH cooling, and just over 12,000 heating so planning on a 12k Fujitsu or Mitsubishi unit. Also ran a preliminary ASHRAE 62.2-2019 with RedCalc (with assumed .1 CFM leakage per sq ft. being a small, tight SIP build) which said I have an outdoor air target of 28 CFM, with required mechanical venting of 28.3 CFM. With that thinking I’ll need something like a Panasonic WhisperComfort ERV in the system here as well. Welcome thoughts on how you guys do fresh air supply on smaller units like this though!