9 of the World's Most Unique Eco-Friendly Buildings

With the constant push to drive down costs and reduce a building's impact on the environment, architects and engineers are coming up with some very interesting building concepts. From using ever more renewable energy sources to improving the way buildings use energy, many unique and eco-friendly solutions are being developed.

With this in mind, here are some of the world's most interesting and sustainable buildings. 

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What are some of the world's most unique eco-friendly buildings?

So, without further ado, here are some of the world's most unique eco-friendly buildings. This list is far from exhaustive and is in no particular order.

1. This is the world's first energy-positive hotel, according to its architects

This hotel in Norway is one of the world's most unique and eco-friendly buildings. Designed by the architect firm Snøhetta, it is billed as being the world's first energy-positive hotel.

Called "Svart" which means black in Norwegian, the building's design was inspired by the dark glaciers of the area where it might be built. The architects also took inspiration from traditional Norwegian fishing equipment and houses. 

With its interesting circular form, it should offer unparalleled 360-degree views of the surrounding fjord and glacier.

2. The proposed new HS2 Interchange in the U.K. is the first of its kind to achieve an "Outstanding" BREEAM assessment

The new HS2 Interchange that is planned to be built near Solihull in the U.K. is another of the world's most eco-friendly buildings. It recently managed to achieve an amazing "Outstanding" certification from its BREEAM assessment. 

BREEAM or Building Research Establishment Environmental Assessment Method to give it its full name is an international standard for assessing a building's sustainability and tends to be used to masterplan projects, infrastructure, and buildings. 

This puts it within the top 1% of buildings in the U.K. for eco-friendly credentials, and the first-ever train station to achieve it. 

3. This eco-friendly building in Berlin is ahead of the competition

Called the "Cube Berlin", this office building is touted as being 25% more energy efficient than other "green" buildings in its class. This, according to its designers, is achieved through smart energy management systems that actually study and learn from its occupant's energy habits.

It was designed by the Danish architecture firm 3XN, the building first opened its doors in March of this year. As its name suggests, this smart office building is designed to resemble a cube, albeit a fractured one. 

4. The Bank of America's office in New York is another of the world's most eco-friendly buildings

Designed by the architecture firm Cook and Fox, the Bank of America's Tower at One Bryant Park, New York is very eco-friendly. It has systems that can recycle wastewater and rainwater, and the tower itself uses passive heating from the sun as much as possible.

Its windows are also designed to allow as much natural light in as they can, reducing the need for artificial lighting. Most of the building was also constructed using renewable materials, where possible. 

These features, among others, enabled the building to become the first commercial high0rise to achieve LEED Platinum certification. Not a small feat. 

5. Have you heard of the "Crystal Island" project in Moscow?

The "Crystal Island" building project in Moscow is another of the world's most eco-friendly buildings. While currently only at the planning stage, this building will become one of the world's largest buildings with an enormous 27,000,000 square feet (8.229,00 meters squared) of floor space. 

The building's most unique feature is the planned installation of a "second skin" that will provide a thermal buffer to the rest of the structure. It will be able to open in the summer to increase ventilation and close in winter to shield the building during Russia's harsh winters. 

6. The Salesforce (formerly Transbay) Tower in San Francisco absorbs emissions from vehicles

The former Transbay Tower (now called Salesforce Tower) recently completed in San Francisco is yet another of the world's most eco-friendly buildings. It towers over the city at 1,070 feet (326 m) tall, and this building features a bus terminal with a glass rooftop park. 

The building's design has been completed to reduce the need for mechanical HVAC with each floor making use of 100% natural air. It also features massive wind turbines on its roof and sunshades for solar control. 

These features have enabled the building to shot for LEED Platinum certification.

7. The BMW Welt building Munich is another of the world's most eco-friendly buildings

The BMW Welt building in Munich is yet another of the world's most eco-friendly buildings. It's strange, and unique, design features a specially designed structure that supports the roof.

Its roof is covered with a massive photovoltaic array that is capable of producing over 800 kW of renewable energy. The building's steel paneling also enables the building to be partially heated using the Sun's energy. 

8. The Clock Shadow Building in Wisconsin harnesses the power of geothermal energy

The Clock Shadow Building in Wisconsin is also one of the world's most eco-friendly buildings. Built on a former brownfield site, this building is already a winner thanks to its reuse of formerly unusable land.

Not only that, but this building makes use of geothermal power to reduce its reliance on less sustainable energy sources. The building's walls and roof are ultra-insulated to massively increase its energy efficiency. 

It also comes with a green roof and 5,000-gallon cistern that provides the bulk of the building's toilet flushing reservoir. This made it the first commercially permitted Graywater flushing system in all of Milwaukee. 

9. Northern Arizona University's Applied Research and Development building is one of the world's greenest too

And finally, Northern Arizona University's Applied Research and Development building is also one of the world's most eco-friendly buildings. In fact, its green credentials are such that it is ranked as one of the world's greenest.

The building features solar power systems that are large enough to provide around 20% of the building's energy needs at any one time. It also has venting windows and automatic shade controls to further trim its energy use. 

All of these features enabled it to achieve an amazing 60 out of 69 on the LEED rating system provided by the U.S. Green Building Council. At the time, only two other buildings had managed such a feat.