Happy Earth Day, earthlings! While you have already witnessed a fancy and very interesting doodle by Google, here is a real estate angle to earth day - Green Buildings.

We all know that Mother Earth is ill. But we all are making small efforts to save her from further deterioration. Similarly, architects around the world came up with the concept of "Green Buildings" to do their bit.

According to Discovery:

"Green building is a trend in the architecture field to build structures that are water and energy efficient out ­of environmentally friendly materials."

Green buildings offer sustainable and healthy operation facilities. These structures focus on efficient energy consumption while preserving and protecting the surrounding environment. Recently, Green buildings have become a fad in the real estate industry.

The U.S. Green Building Council says:

"Sustainable properties are the future of the real estate industry. Consumer demand, residential builders, federal government incentives, and local government policy are making this happen. Many consumers, real estate professionals, and property owners are taking steps towards greening their properties."

In a March Report, published by McGraw Hill Construction, the real estate research unit of McGraw Hill group, revealed that a number of companies are moving operations to "Green Buildings". The report found that the number of firms planning to move around 60 percent of their operations to green buildings from 2002-15 had tripled in South Africa and doubled in Norway, Brazil and Germany. In regions like the U.K., U.S., Singapore, Australia and the U.A.E, the growth was estimated to be somewhere between 33 percent to 68 percent.

While companies are moving towards more sustainable projects, we have compiled a list of some of the greenest buildings from all around the world. Check out the slideshow below: