Despite tough economic conditions, large office complexes continue to be built in major cities throughout the world. ‘Green’ campaigners argue that such developments are inherently bad for the environment, and skeptics point out that by making sustainability central to their new office designs, many companies are simply attempting to offset their environmentally degrading activities elsewhere.

However, considering that large-scale offices will continue to be built, and in increasing numbers throughout the developing world, it is great to see that so many of the new ones are being designed with a low environmental impact in mind. This list comprises 10 existing and upcoming office buildings that are not only bold, beautiful and futuristic, but ‘green’ too.

One Westminster Place [London]

This 18-storey, 345,000 sq ft ‘crystalline’ structure is soon to become the latest architectural addition to London’s Southbank. The offices’ striking glass façade reflects light across a spectrum of colours, creating a dazzling ‘dragonfly wing’ effect. The building, which has been awarded an excellent BREEAM (BRE Environmental Assessment Method) rating, has layered glass walls that create an insulating environmental buffer zone. In summer, hot air from inside the buffer zone can be extracted to create energy.

The Bow [Calgary]

The Bow in Calgary is set to become the HQ of EnCana, North America’s second largest natural gas production company. The 69-storey (236m tall) building, which will house 3,300 EnCana employees, has a crescent shape with a huge south-facing arc that captures light and heat from the sun, lowering the offices’ energy requirements. The Bow is made largely from super-strong steel, reducing the need for building materials by 30 percent.

The Cactus Project [Qatar]

This new building, designed to house the offices of the Qatari Minister of Municipal Affairs & Agriculture, fits seamlessly into Qatar’s scorched, desert landscape. Its design has been inspired by the cactus: it features large, energy-efficient sun shades which open and close depending on temperature, in much the same way as a cactus opens and closes its stomata. The offices have an adjoining botanical dome full of cacti and other plants.

525 Golden Gate [San Francisco]

San Francisco leads much of America on the environmental front. Now, the city is hoping to eclipse all other ‘green’ buildings, by creating the most sustainable office in the United States to house their City Hall. The Civic Administration Tower, known as 525 Golden Gate, will feature integrated wind turbines, shading and solar panels along its facade and roof. Massive windows, light shelves and a central core will flood 255,000 sq ft of offices with daylight. (Update: the 525 Golden gate building has been put on hold courtesy of the credit crunch.)

The Okhta Tower [St Petersburg]

By 2016, St Petersburg will be home to the tallest and one of the greenest towers in Europe: the 396m tall Okhta Tower, HQ of Russian gas giants Gazprom Neft. The Tower has five sides that twist on their upward trajectory, mirroring the movement and energy of water in the River Neva, which surrounds the building.

Okhta Tower has a two-layered glass exoskeleton, providing ventilation, sunlight and thermal insulation against the city’s notoriously bitter winters. The building is peppered with social and green spaces, so that workers need not waste energy in elevators whilst on their breaks.

Fusionopolis [Singapore]

Fusionopolis is the brainchild of architect and fervent environmentalist Ken Yeang. The 15-storey skyscraper, which has a whopping 1.3 million sq ft of floorspace, features a 1.4km long living ‘spine’ of vegetation that is nourished by sunlight, redirected onto it through a series of prisms. The vegetation insulates the complex in the winter, and provides passive cooling in the summer, as the plants transpire and release water vapour.

Ernst & Young HQ [Amsterdam]

Like the Bow, this 24-storey Amsterdam building, which houses the HQ of Ernst & Young, has been designed by the sustainable architecture powerhouse that is Foster + Partners. It’s not quite as adventurous as some of other new builds listed here, but it’s actually been completed and exceeds Dutch environmental building standards by 10 percent.

The building’s 3-storey atrium and huge double-height conference facilities are illuminated with natural daylight, saving on electricity. 65 percent of rainwater falling on the site is retained by the building’s ground-water storage system, and much of it is used to fill a large ecological pond that serves as a focal point at the offices’ entrance.

StatoilHydro HQ [Oslo]

The futuristic new HQ of Norway’s StaoilHydro features five separate wings piled on top of one another in a seemingly haphazard manner. It saves energy by utilising renewable geothermal heat in its district heating and cooling system. Hot water (or cold depending on the depth from which it is extracted) is pumped out of a nearby disused coal mine straight into the offices’ radiators. Once the water in the radiators has cooled, it is pumped back into the mine to be naturally reheated by the Earth.

China Insurance Group HQ [Shenzen]

This asymmetrical, 49-storey tower in the centre of Shenzen is being built for the China Insurance Group. The building’s undulating fa¸ade not only provides shade and ventilation, it increases wind resistance, driving turbines that partially power the offices inside. Further energy is supplied by photovoltaic cells located on the roof.

BBVA HQ [Madrid]

Spanish banking group BBVA’s new HQ, located just outside of Madrid, is interspersed with alleyways for improved ventilation, and gardens for greater well-being. The large tower, which acts as the central focus for the complex, also provides shade for the offices below. Photovoltaic arrays help power the building and rainwater is collected and recycled.