Sustainable retrofitting using natural landscaping

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Is algae architecture the answer to a zero carbon economy in all big cities?

Energy use in buildings is responsible for 26 percent of Australia’s greenhouse gas (GHG) emissions and it is the primary cause of peak energy demand on the electricity network. Ordinarily, heating and cooling buildings accounts for over half of a building’s energy needs. According to the United Nations Environment Programme, buildings use about 40 percent of global energy, 25 percent of global water and 40 percent of global resources, and they emit roughly one-third of the greenhouse gas emissions. Buildings that have been in operation for over 50 years contribute higher levels of carbon dioxide emissions due to inefficient systems and outdated construction.

However, buildings also have the potential to achieve significant GHG emission reductions in both developed and developing countries. Governments and private agencies across the globe are working to develop technologies and tools to control how energy is used, managed and generated in buildings, offices and homes, and technologies that can help power, heat and cool buildings using low-emission local energy sources, including renewables. It is estimated that proven and commercially available technologies can reduce energy consumption in buildings by 30 to 80 percent.

Retrofitting existing buildings through algae landscaping

Apart from the use of common technologies – such as building management systems, cogeneration, cooling towers, energy-efficient lighting, solar energy and water-efficient fittings – there are some natural techniques that can help in the sustainable retrofitting process. These include natural ventilation, the appropriate use of daylight and natural landscaping, including retrofitting buildings with algae membranes.

Today, many existing buildings around the globe are being retrofitted using algae architecture and landscape design techniques. Algae architecture results in increased oxygen production, lower GHG and decreased carbon dioxide emissions. It also requires far less structural support compared to other transparent or glass building systems. Moreover, it is estimated that the carbon footprint of material contributing to algae architecture is up to 80 times less than that of comparable transparent systems.

Cultivated inside laboratories, the algae cultures are fitted along the external length of the buildings using special tubes, which provide a greater surface area to expose the cells to sunlight – crucial for the sustenance of algae. Let’s take a look at two notable examples:

Marina City Towers, Chicago

With an estimated growth of over 30 percent in its residential population and an annual increase of over 13,935 square metres in office space by 2020, Chicago is set for the same challenge as all big cities across the world – how to support economic development while keeping a check on its environmental footprint? To address this, the Chicago Climate Action Plan (CCAP) was formulated, which seeks to reduce greenhouse gas emissions in the Chicago central area by 80 percent (from 1990 levels) by 2050.

The proposal involved retrofitting the existing Marina City Towers, located within the Loop, Chicago’s central business district. The aim is to introduce algae landscaping to help reduce carbon dioxide and other GHG levels in ambient air, reuse water, produce energy on-site and allow food production. A modular system of algae tubes – one located on the top of a tower and one between the parking structures – will absorb the sun’s radiation to produce biofuel. The algae bioreactor is set to produce enough energy to fulfil the overall energy needs of the building.

Federal Building, Los Angeles

The aim here was to create energy self-sufficiency and a zero environmental footprint for the existing building based on the guidelines set by the Living Building Challenge.

The architects and designers from HOK/Vanderweil created a building retrofit design using the Process Zero: Retrofit Resolution process. This design process reduces the building’s overall energy demand by 84 percent, generating the remaining 16 percent on-site. The team of HOK/Vanderweil explains: “The design uses proven energy conservation and renewal strategies, including atria and light wells that bring daylight into workspaces, integrated louvres for natural ventilation, a new façade with more than 3250 square metres of photovoltaic film, over 2787 square metres of rooftop solar collectors that circulate water through floors to help with climate control, and office equipment operated by a cloud computing system.”

Reuse is one of the most sustainable options as we aim for a green future that will transform existing buildings in major cities, where population and GHG emissions are the highest. And algae architecture could become one of the landmark processes on the road to a zero carbon economy in all big cities.

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