"A building is ecological" is like saying "A building is mathematical or biological, philosophical, ..."

Ecological doesn't mean sustainable, it just means "related to ecology". 

Even the people that want it to mean "not harmful for the environment" or "morally good" or something like that will find that the only environment morally good beings actually want to inhabit is a beautiful one. 

Luckily we have a very rich history left by builders of timeless beauty and have a lot more ground to discover.