There’s actually a kind of Moore’s Law for the Internet, which states that the Internet doubles in size every 5 years. About 2.4 billion of Internet users were registered worldwide in 2012. Having more users increases the need for more and larger data processing centers with thousands of servers. One consequence is the excessive energy consumption caused by web servers, which run web applications and web- based services. We propose a short study of energy consumption in relation to web server performance. We also propose a methodology to design energy efficient web systems using virtualization technologies.