A home's location - what city it is in and even what part of that city - is key to this popular question. For example, adding a central air conditioner in to a home in the South may add significant value, while putting one in a home near the Pacific Northwest might not have much impact.
As a rule, the best ROI from renovating a home comes in the kitchen. According to one national survey, kitchen remodels returned an average of 88% of the investment. In other words, a $10,000 kitchen remodeling project would add approximately $8,800 to the value of the home. Bathrooms weren't far behind, yielding 85%. On the contrary, something that may not add value would be painting just for the sake of redecorating.