The Bio Intelligence Quotient (BIQ) is of the most popular buildings among visitors to this year's International Building Exhibition (IBA). The apartment block is green in every sense of the word. Not only is the exterior painted bright green, sporting the words "Cool" and "Photosynthesis" in large type, but the south facing facades are made of glass panels containing green microalgae.
The panels are called bioreactors. Physically, they help shade apartments from the sun: rather like louvers. But inside each bioreactor, photosynthesis is at work, converting sunlight to produce more microalgae, or biomass, as well as heat.
Each of the 129 bioreactors is filled with water and microalgae culture. At regular intervals compressed air is released inside the bioreators forcing large bubbles to slowly make their way through the green microalgae to the surface.
The biochemical process produces biomass which can be harvested for biogas and used for energy, and it generates heat for hot water in the building.
"Urban areas are consuming energy, consuming water, consuming organic matter and you do not really produce any resources in urban areas," says Dr Martin Kerner of Strategic Science Consult in Hamburg - one of the project partners developing the BIQ microalgae bioreactors.
"The vision is to make urban areas productive," says Kerner. "And algae are one possibility to produce biomass in the facades of buildings."
Dr Kerner says the biomass produced is rich in amino and fatty acids and has a range of uses other than biogas: from animal feed to pharmaceutical products. The bioreactors also compete well with solar energy technology in terms of their capacity for producing heat and energy. Kerner adds that the innovative facade on the BIQ house shows how bioreactors offer an aesthetic element for buildings with a function.
"What we have are good looking facade modules. Made in glass, highly attractive. So you not only have a system which produces biomass, heat and that produces something, but you also have something that can be used by architects to improve the vision of urban areas," he says.
A building like a plant
Within the BIQ house, the algae culture, water levels and temperature in the bioreactors are monitored closely. Biomass is collected by filters and a heat exchange system removes heat for heating and hot water.
As a smart house of the future, the BIQ house aims to be energy self-sufficient and become a living part of the urban infrastructure and ecosystem. For example, it can reduce carbon emissions from neighboring buildings by using carbon dioxide as a nutrient for the algae, or direct any excess hot water to local services.
Dr Jan Wurm leads research in the BIQ project for the engineering firm Arup. He says decades ago buildings were considered a "closed box" that had to be heated in specific way. He says the approach led to heat loses and high energy consumption.
The BIQ system uses biochemical processes instead.
"It's exactly the same biochemical processes on every plant, but we use it on a bigger scale for the benefit of a building," says Wurm.
Dr Wurm says the bioreactors are just another way of building houses in harmony with their environment - the same way as a house built beside a tree gains shade from leaves in summer and warmth from the sun in winter when the leaves fall.
"I think there is a fascination of a building skin behaving similar to a plant - very dynamic, very interactive to the changing external conditions," says Wurm.
Dr Wurm says it is first time that technology and the natural cycle of plants have been interconnected to provide energy for a building in this way.
As more cities look towards renewable energy, incorporating nature into urban areas, and adapting spaces such as rooftops for farming, Wurm says he is confident the bioreactor facade will send a strong message to the building and construction industry.
"This project is saying for the first time: 'yes, we can do it, the technical systems are there, and it works.'"
But the cost of the entire glass bioreactor facade system is an expensive proposition for a building developer. It's hoped over time costs will fall - the same way that solar energy technology is becoming more affordable.
Smart house of the future
The BIQ house is only one of several "Smart Material" houses on display at the International Building Exhibition. So it's not alone and it has its detractors.
Most of the BIQ's 15 apartments are occupied by "real" tenants - but living in a house of the future also means being part of an experiment. And that's not always a pleasure.
Each bioreactor makes a loud rhythmic aquatic pumping sound as compressed air is released inside.
The exhibition's project coordinator Hubert Lakenbrink says many tenants in the BIQ house don't mind the noise because they feel it is part of the experience. But others admit they would prefer the system would shutdown completely when they're trying to enjoy the sun out on the balconies.
Dr Kerner says the project managers are listening to what people say about the bioreactors, and that the system will be refined.
The next generation of glass bioreactor panels may incorporate solar photovoltaic cells to produce electricity. And if you're not too keen on the green, you may be able to get your algae in different colors too.