Built environments nowadays use traditional building methods of both light and heavy construction. This creates urban environments full of grey and bulky reinforced concrete buildings and curtain wall buildings that suffer from heating and ventilation issues. The modern research presents the figure of sick building syndrome  which affects the mental and physical health of people living in such habitats. Lack of ventilation and natural light are some of the causes of the effect. The hard contrast between indoors and outdoors should be rethought in order to create new approaches to our modern habitats. A softer and more dynamic edge, one that differentiates the interior thermal zone from the exterior, has the potential to change the perception of living spaces in modern architecture.

Sustainable approaches have led to a new field in architecture: passive buildings. This method takes advantage of the thermal characteristics of materials and uses specific site analysis to predict light, ventilation and thermal behavior in different seasons. After analyzing the site, a tailored solution is planned for the building that reduces the structure’s power consumption during weather changes. Such low carbon consumption buildings tend to insert natural diffused light from different facades, allowing natural ventilation while keeping thermal comfort for indoor zones. Different governments worldwide have created new green building policies to increase the use of this method.

A precedent for passive buildings using algae bioreactors as an energy source is the BIQ House in Hamburg, Germany. The building algae façade was developed and built by ARUP with Germany’s SSC Strategic Science Consultants and Austria-based Splitterwerk Architects. The exterior skin of the building is made from photobioreactors, while the micro-algae growing in the glass louvers provide a clean source of renewable energy. Periodically, algae are culled, mashed into biofuel, and burned in a local generator to produce power. The result is a building shaded from the summer heat by algae foliage and insulated from street noise that self-generates the power to sustain its own harvesters, heat, and electricity. The BIQ supplies 50% of its energy consumption using the algae biomass.

The BIQ is a revolutionary living reference for fusion of Micro-CHP system that is fed with algae biomass produced by the building itself. The short supply pipes, all within one structure, use the advantages of the CHP (cooling, heating, and power) with incredible efficiency (appendix 2). The visionary thinking of self-sufficient houses that are independent of industrial power plants points to applications far beyond urban environments, such as rural areas, third world countries, and disaster zones. In order to enable this idea, a lighter, modular, mobile approach must be developed.

This approach led me to develop the Micro-House, which uses photobioreactors as structural units brought to the construction site as modular pre-manufactured units. The units are placed on a light iron skeleton and placed on a molded concrete precast foundation. On-site foundation beams that carry the concrete precast and iron skeleton could be built in only seven working days. Then the photobioreactors are delivered to the site, placed on the iron skeleton and connected to the plumbing and electrical systems. This system provides quick building ability and reminiscent of curtain wall installation. The method uses bioreactors as structural walls, and not only as sources of shade, and offers numerous advantages.

Different configurations of foundation and bioreactors assemblies can create various spatial arrangements to create varied houses. Photobioreactors used for algae cultivation use repetitive horizontal pipes to exploit the volume of fluid in the system. Adapting the bioreactors to structural walls demands breaking the repetitive volume, to create gaps that can be used as windows. The chosen basic bioreactor type was the plate bioreactor (appendix 3) which has a square section and creates a continuous wall section that enables the creation of an internal thermal zone. Different modifications of the current bioreactors were investigated, considering structural strength, isolation, water circulation efficacy, and design performative variations.

After placing the photobioreactors and connecting it to the pipe system, the first supply of water and algae are needed. As the system is a closed loop, no significant leaks should occur. Some algae are fed up to the bioreactor after harvest as well, which makes the first feeding of the structure a one-time event. Later, filtered water is supplied to the upper part of the structure: its roofs. Water circulation is accomplished with gravity by connecting the roof and wall bioreactors. This is made with a water pump connected to the filtering unit.
The system is also supplied with CO2, as a raw material for the algae photosynthesis. Some research indicates that CO2 from burned wood source performs the best for algae cultivation. This feature supports cooking over wood fires, which is common in rural areas and third world countries. The CO2 would flow from the cooking area through pipes towards its insertion into the bioreactors from the bottom parts, for homogeneous spread throughout the fluid.

When algae cultivation reaches a sufficient point, harvesting of the bioreactors occurs. The algae containing fluid goes through a filtering system to separate the biomass from the water. The water, which warms up due to the heat over the bioreactors, is cooled using a geothermal system. As geothermal systems are expensive and are built over a long period of time, other adaptions could be made. Other solutions include running the water through an underground pipe system to encourage heat lost, and using the water in the CHP method for cooling. When using micro-CHP for separate structures, the two solutions combine as water pipes run underground towards the CHP unit. The cooled water is supplied back to the bioreactor with the water pumps.

 

Algae reproduction rates are directly connected to the amount of sunlight they are exposed to. When using photobioreactors as structural units, the structure reacts to climate changes. In summer, the radiation increases and leads to rapid growth of algae. When algae grow, the fluid becomes opaque – this blocks direct sun rays and inserts diffused light into the house. This blocking of direct sun rays helps to keep the house thermal zone cool in summer. In winter, the radiation is lower, which leads to slower algae growth, the liquid in the bioreactors becomes half transparent, which allows more light to get into the house on cloudy days, and even allows the direct sun to warm the structure.

Harvesting can be performed at different cultivation rates, determined also by light insertion aspects. The harvested biomass is used to produce energy as described in the micro-CHP description. When used in rural village areas, CHP system efficacy grows when it is supplied with biomass from multiple houses, supplying them with electricity, heating and cool water. The short distances between the structures and the CHP unit use the full potential within the CHP method.

Water pipes are placed within the concrete precast used for the house foundation. When driving cold or hot water through the pipes, the heat or cold change the concrete’s temperature, which affects the house’s interior air temperature. This method has been used in architecture since the Romans. In the summertime, cool water from the geothermal/CHP system is run through the pipes in the concrete, creating a cooling effect indoors (appendix 5). In winter, water warms up in the bioreactors and, after filtering the biomass, the warm water runs through the concrete, a process that cools it before it is returned to the bioreactors. Using the CHP heating feature and cook fires are additional potential heating sources.

New research around the globe uses algae to produce food and nutrients. An Israeli project called "Just Spirulina" is using spirulina algae, a superfood that contains all the essential nutrients a human body requires protein, omega 3, antioxidants, vitamins, and minerals. The project’s essence is sending volunteers to third world countries and teaching them about spirulina algae algaculture. Using structural bioreactors for algaculture would make the structure yield food for its residents. Another possible application is using glowing algae in small bioreactors hung from the ceiling as light sources. That is a mind-changing idea regarding the relationship between housing, agriculture and humans.