The trend towards more efficient office space continues to grow. Once, companies planned 250 rentable square feet per employee, with efficient spaces holding a worker in 200 or 225 feet. Some companies now operate with a density goal of 175 rentable square feet per worker. However, a combination of technological innovations, shifting client needs and more flexible working styles are making it possible to achieve much higher levels of efficiency. Here are the top three types of businesses that can usually shrink their spaces without sacrificing productivity or morale.