The Passive House - is a 25 year old building system founded by a group of German and Swedish architects to prove that insulation and airtight construction can cut energy costs in a typical building by as much as 90%.

The idea is that a properly insulated building needs far less artificial heat and it retains heat gain from the sun and the people inside. The concept is very popular in Europe.

Curbed says that this thermal image was taken on a freezing night in winter and while its neighbors were leaking red and orange heat all over, 23 Park Place which is right in the middle looks completely blue.
Soon the whole city will look like this. You won't see the change, they will just be there looking like the rest. But they are different, like a ghost building that was nearly removed from the energy map. It sits there consuming less, giving more and caring for their occupants while the city goes on around them.
[http://ny.curbed.com/archives/2013/04/19/nycs_first_certified_passive_house_is_super_cool_literally.php?utm_source=feedly" onclick="window.open(this.href);return false;">Curbed]