Does adding Central Air to a home add significant value?

[Eric Bellefontaine]

So I've been looking at some homes in my area, they are all older homes over 100 years old. I was wondering how do you determine if a renovation is going to add any significant value to a home? For example a lot of the homes I was looking at have Window A/C units, if you add central air does that add any significant value?

[Brian Ellis]

For resale in a B - A class single family residential neighborhood, definitely. 

If most of the surrounding homes have window units, there is most likely a reason for it. Are they all rentals? If so, I wouldn't think central air would add much value to a home. Appraisers look at GRM

Someone with more knowledge might chime in and correct me if I'm wrong though.