My latest conundrum with the shed project is how we will keep it heated during the winter months and cool during the summer months. Seemingly, the best option is to install a heat-pump of some sort in one (or more) exterior walls. However, this introduces a hole in the wall that must be properly handled for fear of sound escaping through this conduit to the outside.

S-box design

S-box to allow the flow of air but dampen any sound leakage (in or out)

I assume copious amounts of acoustic caulk and insulation will help. I’ve also considered building a sound-dampening box in front of the unit to help reduce fan noise and sound leakage.

Essentially, it would be a rectangular frame with two opposing, short walls on the inside. The entire inside of the box would be lined with rigid fiberglass insulation or some other dense material to dampen escaping sound.