1,123 posts, read 4,776,897 times 19,537 posts, read 39,700,426 times Originally Posted by spacelord75 Can you cite the source of this wisdom?I suspect that you're missing a qualifying statement. The house is old, and the garage is very drafty and I don't want to drop a couple grand for minimal improvement. Start with the root cause of heat loss/gain. Then work on ventilation and tempering the air as needed. 25,542 posts, read 52,565,173 times Well, I'm a CPA so I don't have a ton of time to spend researching nor expertise in the field, so most of my sources are anecdotal by nature and/or from talking to some people in the energy audit field. To fully insulate the 20'x25' garage walls and ceiling with spray foam (which would likely be the best route given the air leaks associated with batt insulation) would likely cost me $5k at least, plus adding new garage doors with proper R value would tack another $1k (at least), plus given the fact that I can't really insulate the ceiling of the already finished space and have knee-walls which will let in tons of outside air as well...it just

seems like a losing battle and a ton of money to boot. Obviously I know solving the root cause is the best approach, but sometimes that isn't feasible. So my follow up question was, how effective/efficient are mini-split ductless units in such a scenario? it'll be quieter than a window a/c. 8,933 posts, read 33,229,739 times Last time I looked, batt insulation has nothing to do with air leaks. F/glass insulation works best when encapsulated. Air leakage is from lack of sealing joints i.e., mating surfaces of dislike materials (like slab and wall plate), or joints between sheathing, or unglued drywall panels, or wall plate to subfloor. 3,303 posts, read 6,169,063 times 8,459 posts, read 11,040,358 timesThe COOLAdvantage Program provides rebates for energy efficient central air conditioners or heat pumps as well as "best practices" on proper sizing and installation that affect operating efficiency.You can now Apply Online! Note: The SEP funding is currently available for oil, propane and municipal electric customers who wish to participate in the Home Performance with ENERGY STAR, WARMAdvantage and COOLAdvantage Programs.