If you build green brownstones you build homes that don’t breathe without help. A green home is a well sealed and insulated home. It does not have all the normal cracks through which the house normally breathes (and leaks!).

So you need to make up for that. There are different opinions but right now I like Heat and Energy Recovery Ventilators, aka HEV and HRV. In Brooklyn I like Energy Recovery Ventilators because that also takes care of humidity.

Check out this web site because it gives a great run down on Heat and Energy Recovery Ventilators.