While it might well be the case that most people don't associate green homes with affordable housing that doesn't mean that the two don't have something in common. In fact, you might be surprised to learn that if there is anything that tends to have a lesser carbon impact it would be multifamily housing. Anyone who has taken a carbon footprint test while living in various types of housing will tell you that the larger one's home, the bigger the footprint. Living in an apartment building or a dormitory is probably the best way to find yourself with a smaller footprint.
Obviously, there are many other components to being green when it comes to housing, from building materials to energy efficient appliances to the lifestyle choices of those living within. All said and done, such factors such as location will also play a big role because of the amount of driving required on a regular basis. That being said, with more and more building projects embracing environmentally friendly designs and the fact that multifamily homes are often more green, affordable housing may become a greener and greener choice over the coming years.