Newbie, having to deal with unsightly, noisy HVACs from the bldg next door isn't uncommon. In NYC, space is limited, bldgs are close together, and we can't change that.

It sounds like the bldg next door is trying to help you. A lot of bldgs would just say "too bad". If the green plastic fence they put up is ugly and blocks light from getting to your apts, a couple ideas you could suggest to them:

- Put up an open-weave fence (e.g., chain link, lattice) - something to generally hide the HVACs from your view but allow more light to get through to your bldg.

- Put an enclosure around the individual HVAC units instead of a wall of fencing between your bldgs so at least you look at that, not the HVACs, and get more light. There are enclosures (I've heard them called "cake covers") that fit over various rooftop units. They look like a shed like you see in backyards for tools/garden equipment.

As for the HVAC humming sound, an enclosure like the above may muffle it. Everyday noise within individual apts may override it. People, especially in a place like NYC, also learn to adapt. Your residents may get used to it. When I was growing up, we lived not far from an elevated subway line. Visitors from out of town used to ask how we could stand the noise. Our standard reply was "What noise?"