Bio-facades

It is becoming increasingly critical to ensure built environments are efficient and that air quality, CO2 production, and greenhouses gas emissions are managed. At the same time, as cities densify and the population grows, urban space is at a premium. Using vertical space, that is the facades of existing and new buildings, to generate renewable energy is an innovative way to address these issues. An algae bio-energy façade is a system that uses live algae cultures to generate energy and biomass. The façade consists of glass panels, or ‘photobioreactors’ that are filled with nutrient-rich fluid that serves as a habitat for algae. Daylight and carbon dioxide help the algae to grow. The biomass and heat generated are retained in the reactors in an energy management system. Biomass is harvested through flotation and the heat by a heat exchanger. This can serve as a heat source for the building.  

The façade system becomes an integral part of the building and can be part of windows, doors, and structure. The algae can also act as shade. This means the hotter the facade gets, the more the algae grows, creating more density, and therefore shading in the panels. 

As cities grow and densify, this strategy might make an urban building facade productive in a way that traditional buildings are not. A city’s facades make up a large area and are currently underutilised as a potential energy generation surface. By using vertical space in this way, to create renewable energy and grow biomass, opportunity arises without the need to use any more urban land. 

Bioenergy façades are considered state-of-the-art technology for high-performance architecture. They may have the potential to contribute to lower ecological and carbon footprints of buildings, but this is still a developing field (Azari et al., 2020). 

There are currently no examples of bio-facades with algae in Oceania, but the system is being developed in Europe and could perhaps be applied in an Oceanic context. 

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Name of NbS

Bio facade

Type of NbS

Created or constructed living ecosystems

Location

  • Building
  • single site
  • urban

Relationship to Indigenous knowledge

This nature-based solution utilises modern technology and construction methods. It is a technical, science-based way of using biomass to create renewable energy. At this stage, there is no focus on Indigenous knowledge specifically. It is being developed and tested in Europe, in countries such as Germany.

Climate change benefits
  • Increased temperatures
  • Urban heat island effect

The algae creates heat, creating a carbon-free heating and hot water source, that uses no additional land use. The system has been proven to work in the BIQ House in Germany, where a bio-facade was monitored for its technical and energy performance, and proven to be generating a net energy gain. The system can be retrofitted onto existing buildings too – meaning this is a solution that could be added in the future as a renewable energy solution. 

The closed loop system creates carbon reduction on three levels: direct carbon sequestration from the air (used to feed the algae), absorption of carbon (by the algae) and a reduction in energy use. Hanafi (2021) concludes that retrofitting a bio-facade onto a commercial building could reduce electrical energy consumption by 45-50% and significantly reduce carbon emissions. 

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Societal / socio-cultural benefits
  • Energy security

It is estimated that by 2050, 70% of the world’s population will live in cities. As cities densify, we need to find ways to improve air quality, lower carbon emissions and create comfortable, healthy cities. Bio-facades can be retrofitted onto existing buildings and implemented as parts of new buildings to create healthier buildings that generate their own renewable energy. 

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Ecological and biodiversity benefits
  • Education and knowledge
  • Production of fuel / energy
  • Nutrient cycling

Integrating nature and natural materials into design is key to future development. Algae is an almost unlimited source of energy and food, and absorbs CO2 at a rapid rate. Algae grown from bio-facades has the potential to be converted into renewable fuel stocks such as biomass or biofuel (Kim, 2013).

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Technical requirements

The system requires the building to have an energy management centre, where biomass is harvested through floatation, and the heat is managed through a heat exchanger (Arup, 2013). The excess heat needs to be stored or transferred to supply hot water. Advancement of this system and making it more readily available, maintainable and easy to install requires collaboration between disciplines. 

Issues and Barriers

This system has not yet been tested in Oceania. The technology has been developed in Europe, so a key barrier would be adapting the research to an Oceanic context.

Opportunities

There is an opportunity to investigate bio-facades with algae in an Oceanic context. Towns and cities are densifying rapidly, and both our infrastructure and available land is struggling to keep up. Many communities in Oceania are dependant on non-renewable energy sources and will need to transition to other energy sources. Implementing facade systems with algae is an opportunity to be leaders in the Southern hemisphere in this technology.

Future projects: French studio XTU Architects has developed a concept for four twisting glass towers in Hangzhou, China, featuring façades covered in panels impregnated with micro-algae. Source: https://www.outdoordesign.com.au/news-info/micro-algae-creates-its-own-energy/6088.htm
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