they look like steel windows, check out brombal usa

They are Steel windows and the company who manufactured them is HOPES windows.

Please see the previous answer by awisnoski. He is Poss Architecture + Planning's lead designer and the designer of this house. Thank you for your interest.

skmarriott,
Our Renaissance Solid Bronze Windows and Doors are manufactured in San Antonio, Texas and shipped nationwide.
Some of their unique features include narrow sight lines, high strength, low maintenance, and custom sized to each opening. All of our windows come fully glazed with triple seal glass & mounting flange options for installation. You are welcome to contact jerry@solidbronzewindows.com or call our office 210.832.8040 with your project details and we will gladly assist you.

You are welcome to view our ideabooks or product video & website-
http://www.houzz.com/projects/152134/Renaissance-Solid-Bronze-Windows---Doors-by-Progressive-Solutions
http://www.houzz.com/projects/573835/The-von-Behr-Estate-in-Sisterdale--TX
http://www.houzz.com/ideabooks/28621235/thumbs/Black-Living-Room-Windows-www-solidbronzewindows-com
http://www.houzz.com/ideabooks/27094077/thumbs/Black-Kitchen-Windows

http://blog.werefindinganswers.com/gallery/renaissance-bronze-windows-doors-2

http://solidbronzewindows.com