Tapestries as DIY sound insulation

In the Middle Ages, many cavernous halls displayed woven tapestries as symbols of status. However, living in a time of fiberglass insulation and central heating, we often forget the lack of sound-deadening qualities these large, cold halls exhibited, making large tapestries more than pieces of art, but a sound-proofing tool that protected againsted the damp, chilly winters. Tapestries had the further advantage of being easily transportable between residences while often depicting historical events.

Source: Dayton Art Institute, Wikipedia

Revolving Doors

One eighth the amount of energy is lost by using rotating doors than conventional doors.

Source: Lance.