what is a thermal envelope

When it comes to building a home that’s eco-efficient and comfortable to live in, building it right is about building it tight.  What does that entail? It means that the lived-in areas (spaces that you use energy in to heat or cool them) have to be clearly separated from those that aren’t. In other words, there must be a tightly sealed thermal envelope around the home, or else hot and cold air will quickly enter or exit the house.  But…