Solar architecture

The idea of passive solar building design first appeared in Greece around the fifth century BC. Up until that time, the Greeks' main source of fuel had been charcoal, but due to a major shortage of wood to burn they were forced to find a new way of heating their dwellings.[1] With necessity as their motivation, the Greeks revolutionized the design of their cities. They began using building materials that absorbed solar energy, mostly stone, and started orienting the buildings so that they faced south. These revolutions, coupled with overhangs that kept out the hot summer sun, created structures which required very little heating and cooling. Socrates wrote, "In houses that look toward the south, the sun penetrates the portico in winter, while in summer the path of the sun is right over our heads and above the roof so that there is shade."[2]

From this point on, most civilizations have oriented their structures to provide shade in the summer and heating in the winter. The Romans improved on the Greeks' design by covering the southern-facing windows with different types of transparent materials.[1]

Another simpler example of early solar architecture is the cave dwellings in the southwestern regions of North America. Much like the Greek and Roman buildings, the cliffs in which the indigenous people of this region built their homes were oriented towards the south with an overhang to shade them from the midday sun during the summer months and capture as much of the solar energy during the winter as possible.[3]

Active solar architecture involves the moving of heat and/or coolness between a temporary heat storage medium and a building, typically in response to a thermostat's call for heat or coolness within the building. While this principle sounds useful in theory, significant engineering problems have thwarted almost all active solar architecture in practice. The most common form of active solar architecture, rock bed storage with air as a heat transfer medium, usually grew toxic mold in the rock bed which was blown into houses, along with dust and radon in some cases.

A more complex and modern incarnation of solar architecture was introduced in 1954 with the invention of the photovoltaic cell by Bell Labs. Early cells were extremely inefficient and therefore not widely used, but throughout the years government and private research has improved the efficiency to a point where it is now a viable source of energy.

Universities were some of the first buildings to embrace the idea of solar energy. In 1973, the University of Delaware built Solar One, which was one of the world's first solar-powered houses.

As photovoltaic technologies keep advancing, solar architecture becomes easier to accomplish. In 1998 Subhendu Guha developed photovoltaic shingles, and recently a company called Oxford Photovoltaics has developed perovskite solar cells that are thin enough to incorporate into windows.[4] Although the windows are not scaled to a size that can be taken advantage of on a commercial level yet, the company believes that the outlook is promising. In the company’s mission statement they state, "Moreover, through the deployment of solar cells in areas where solar has traditionally struggled, for example the glass façades of high-rise commercial or residential buildings. In both cases, allowing solar energy to contribute a much higher proportion of electricity than is possible today, and helping to position PV as a significant factor in the global energy market."[5]

One of the first large commercial buildings to exemplify solar architecture is 4 Times Square (also known as the Condé Nast Building) in New York City. It has built-in solar panels on the 37th through the 43rd floors, and incorporated more energy-efficient technology than any other skyscraper at the time of its construction.[4] The National Stadium in Kaohsiung, Taiwan, designed by the Japanese architect Toyo Ito, is a dragon-shaped structure that has 8,844 solar panels on its roof. It was built in 2009 to house the 2009 world games. Constructed completely of recycled materials, it is the largest solar-powered stadium in the world and powers the surrounding neighborhood when it is not in use. The Sundial Building in China was built to symbolize the need for replacing fossil fuels with renewable energy sources. The building is shaped like a fan and is covered in 4,600 square metres (50,000 sq ft) of solar panels. It was named the world's largest solar-powered office building in 2009.

Although it is not yet completed, the Solar City Tower in Rio de Janeiro is another example of what solar architecture might look like in the future. It is a power plant that generates energy for the city during the day while also pumping water to the top of the structure. At night, when the sun is not shining, the water will be released to run over turbines that will continue to generate electricity. It was set to be revealed at the 2016 Olympic Games in Rio, although the project is still in the proposal phase.[8]

Using solar power in architecture contributes to a world of clean and renewable energy. This is an investment: the initial price is high, but afterwards, there is nearly nothing to pay. On the contrary, fossil and fissile energies are cheap in the beginning, but cost tremendous amounts to humans and nature. The Fukushima catastrophe is evaluated to cost 210 billion dollars to Japan,[9]. Global warming has already been a cause of species extinction.

Solar architecture is then anti-crisis. If all houses were to be rebuilt to meet solar architecture standards, this would bring hope, jobs, money, and economical growth.

According to an article on ECN's website titled "Architects just want to develop attractive buildings", an architect's main purpose is to "create a spatial object with lines, shapes, colours and texture. These are the challenges for the architect within the customer's programme of requirements. But they do not immediately think of using a solar panel as an interesting building material. There is still much to be achieved here."[10] In the article it is stated multiple times that solar panels are not an architect's first choice for building material because of their cost and aesthetics.

Another criticism of installing solar panels is their upfront cost. According to energyinfomative.org, the average cost for a residential solar system is between $15,000 and $40,000 (USD), and about $7 per watt.[11] In the article, it says that at today's rates, it would take 10 years to pay off an average system. As a solar panel may last more than 20 years,[12] in the end, it becomes a benefit.

• Sustainable architecture
• Building-integrated photovoltaics
• Solar thermal collector
• Solar cooker
• Solar chimney