I have a cooling dilemma that I was wondering if anyone here could offer some insights or suggestions for. My kitchen is a ruthless hotbox in the summer months due to its west-facing exposure and having plenty of glass (picture large floor-to-ceiling windows on the West wall and two Velux skylights on a 45 degrees slanted ceiling). Naturally, during sunny days in the winter it serves as a passive solar heat collector. So I am considering the following approach to deal with the heat load during summer time and capturing all generated solar heat during winter. I should also probably mention that I have pretty wide open floor layout, the existing cabinets are gutted, and I’ll have unrestricted access to the walls.
1. Currently in my 130-140 sq. ft kitchen there is no return line. Obviously code, architects and installers were more concerned
with cooking fumes than the unbearable summer heat. I remember reading somewhere that with every foot in height the temperature rises approximately 0.5 to 0.75 degrees, so in my case delta T between the floor and highest ceiling point can potentially reach up 10 degrees or even higher. Obviously there are several relatively simple and straight forward approaches to resolve those issues and I am listing the simple ones first:
a. Replace all glass on the wall with more efficient material; (very expensive and barely effective)
b. Replace Skylight regular glass with nanogel filled glass (new technology used by NASA to provide heat shield on spaceships); (very expensive and extremely effective)
c. Install blinds / shutters, either manual or solar controlled o existing skylights (I am not really sure about potential benefit).
d. Replacing hot halogen bulbs with much cooler LEDs should provide slight measurable relief.
2. Beyond the low-hanging fruit, let’s consider some more involved solutions:
a. Installation of inline 150-200 CFM exhaust fan (Soler or Fanteech) between the sloped ceiling rafters with exit @ the outside wall rather than roof (I do not want to deal with creating an opening in wooden shingle roof) with 2 purposes in mind.
i. Provide adequate cooking fumes exhaust outside throughout entire year.
ii. Provide some relief during hot summer by pulling hot air from under the ceiling and throwing it outside. I do painfully realize that this may have questionable benefits as outside hot air (granted a little bit cooler than the one collected from under the ceiling) will enter the house but assuming that A/C will be on at that time this air should mix with much cooler one so overall effect of installing inline fan maybe not at all w/o merits. This is just my gut and I can’t offer anything more of substance at this time.
b. Bring the return line to the basement to main return line and install intake grill as high as possible, however I also read somewhere that I need serious calculations in order just to extend that return as balance of return lines vs. supply will change. So, the question is do I have to bring another supply line to the kitchen (I can’t see how it will hurt) or should I close somewhere on the same floor return register? What would be the most sensible approach to address this issue?
c. I have currently 2 dedicated Carrier / Bryant 20 year old AC/heating systems, 1 per floor, with cooling capacity of 3 tons each. I am not planning to replace them with anything else right now as I am tinkering with idea of advanced and efficient geothermal installation.
d. Instead of messing around with the return line, how about installing an 11000 BTU dedicated mini split ductless A/C? This seems the least desirable approach but is definitely the most efficient one. I dislike this solution because maintenance is high and electricity costs are only on the rise.
TIA to everybody who can shed some light for me