5 ft wide is too narrow. 6 ft minimum for a stunted iguana is the bare minimum, even though most owners keep their igs in much smaller habitats. with a properly designed vivarium, your ig will stress out far less, and live longer.
36" deep, and how wide?
By "all glass", do you mean no wooden corners? No framing at all? 1/4", 3/8", and 1/2" acrylic can be heat bent to make the corners, which is elegant but it's very expensive. There are fish tank manufacturers who have that technology.
For your iguana, acrylic is warmer because it transmits heat slower than glass does. It creates less of the cold drafts problem.
Check this collection of articles by Melissa Kaplan. It has a lot of peer reviewed content about iguana care. The one about habitat design is very good. Scroll down until you find the habitat article:
5' high is OK because green iguanas can easily adapt to a terrestrial (as opposed to arboreal)habitat. This size tank should be set on a 2 1/2 ft tall wooden base so your iguana can feel safer at the higher position. 30" deep is Ok: few want a habitat that deep but the deeper the better. How about 7 feet wide? If your ig is significantly shorter than the norm, 6 ft wide may do well. The widely accepted minimum width is 1.5 X STL (snout-to-tail length.). Anapsid shows you the documentation of proper habitat shapes.
The hot zone, the cool area, the UVB illuminated area, and the general lighting must be properly placed. This habitat needs a good thermostat. It also needs shelves on the back wall. Plus other details.