And while not directly HVAC, a comment elsewhere in the thread made me think of another point as far as indoor air quality - consider a central vacuum system.

And while not directly HVAC, a comment elsewhere in the thread made me think of another point as far as indoor air quality - consider a central vacuum system. The noisy power unit with the blower can be in a garage or basement (instead of at your feet!), the hose and power head are light. If you don't have carpet and only hardwood/tile/solid surfaces then you can get a hose without electrical for the power head, and a brush wand head - extremely light! My hallways, kitchen and a few high traffic rooms are all solid surfaces and it takes me five minutes to get the hose out, plug it in, vacuum the floor and then put the hose back. Faster than sweeping or mopping and I have a flexible hose that expands/contracts as needed. Very convenient. And best of all (especially since I have allergies) it exhausts all the vacuumed air outside. Central vacuums are far more powerful than any hand operated vacuum you can get - and like a said a heck of a lot quieter too.