Here is one of our posts on passive houses and energy efficiency. It has been published in several online editions: Trud newspaper, 24 Chasa and Bulgaria Today.
You can read it on one of the links below:
http://www.24chasa.bg/Article.asp?ArticleId=5096724
http://www.trud.bg/Article.asp?ArticleId=5096755
http://www.bgdnes.bg/Article/5096761