The interior color scheme is cool, and the use of black metal frames for the bar chairs and coffee table help to create a light and airy room. Rugs are very useful in home decorating. Not only do they give interest and provide a soft surface to walk on, but they can also 'mark out' areas such as this one.
On a treadmill, you can accurately set your incline by 1%, 2%, etc. When walking outdoors, you need to use a tool such as MapMyWalk.com to map out your walks and see what the incline really is. I can tell you from experience, that a 5% incline is a real huffer-puffer. 1  for every 1% of grade, you increase your calories burned by about 12% or about 10 more calories per mile for a 150 pound person.  By the time you are at 10% grade, you are burning over twice as many calories per mile.
Dr. Bryant from the American Council on Exercise said in an interview for an article for The New York Times that walking up stairs at a moderate intensity burns five calories a minute for a 120-pound person and nine for a 180-pound person.