Solar glass: waving at my own reflection

 We found ourselves driving past the building on the way to Bridlington where we used to wave at our own reflections from the coach.

Now I suspect that the glass is so reflective because it is south facing and has been treated with a coating to stop the occupants overheating as though they are in a greenhouse whilst letting in plenty of light. They seem to call it Solar Control Glass. I couldn't find details on the specifics of the coating but I did discover info about what are called G values for glass. This is the fraction of the heat from the Sun that is transmitted through the glass and into the building. I am familiar with U-values for insulation but I've not come across that before. Click here for my source of information and here for some typical values if you scroll down. I'm guessing smaller G-value is better in this context.