if you look at that building you will see, above the windows, are large metal cases that hold rolldown shutters, that were intended so that they could separate the building from another 1906-style configuration, and continue to pump water out of the bay to this separate water system for -- so that they can -- and it was put in place after the '06 earthquake, when of course all of the water supplies failed in the city for fire protection. it's a great building. >> next question i have is if you can describe what's the difference between glass and glazing? >> glass is the noun, glazing is the verb and a glazer is the person that puts in the glass who glazes the glass. so glass is just the term for any one of these products, are glass. glazing is the process of putting in that glass, and you would put it in sometimes what people would call a glaze or putty. that's -- and -- the a archaic name of the man that puts it in is glazer. >> is there a way to create a more effective glass without the air-space issue? >> what happens is that air-space in between does not transmit heat because the t