There are a number of factors driving small space design, and space saving design trends these days. Among the factors are environmental concerns, which create a need for smart, conservative innovations to maximize energy efficiency. Smaller, conservative designs use less materials, and have a lower impact on forest products and other resources. Another factor is cost. The average building cost in the San Francisco Bay Area is around $400 per square foot. Smart, space saving design minimizes the amount of materials you have to buy, thus saving you hundreds, maybe even thousands of dollars.