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Contributions from
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Focus
Innovative milieus
“My real education was working in the slums“
Finding ways out of poverty
Energy efficiency for Rio de Janeiro
Split households
12/2004
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Energy efficiency for Rio de Janeiro
Like many emerging economies, Brazil’s demand for energy is growing. Rio de Janeiro is developing concepts for urban development and architecture to keep a check on energy consumption even as living standards rise. There are many options including whitewashed huts in shantytowns, appropriate ventilation concepts for climatisa-tion, intelligent use of daylight or shading and cooling systems based on evaporation.
[ By Michael Laar ]
Fossil energy sources are problematic in many senses. For instance, they are of limited availability and contribute to climate change. Nonetheless, their consumption is increasing in developing and industrializing countries. While advanced nations, the main consumers of energy, are considering ways to become independent of fossil fuels, this debate has hardly begun in poorer countries. Many countries in the South are repeating the mistakes made by the rich world, thus missing an opportunity for sustainable and more energy efficient development. And yet, there are a number of options that might help these nations fulfil their legitimate dream of higher standards of living without having energy consumption increase exorbitantly.
Mobility and housing
The Western model, particularly the one of the USA, emphasises the desire for mobility in one’s own car. Some reasons are quite pragmatic. In large agglomerations, people often have to travel a long way between their home and their workplace. As public transport is completely insufficient in cities like Rio de Janeiro, it is not hard to understand why people would want to have their own car. At present, only 28 of 100 cariocas (as the residents of Rio call themselves) own one. In Munich, there are 58 cars for every 100 residents; in Los Angeles, 86. Accordingly, the growth potential in Rio is enormous.
Another crucial factor that has led to an increase in energy consumption is the desire for more creature comfort at home. The well-to-do already spend some 77% of their day in air-conditioned rooms, either in their own apartments, in shopping malls, schools, cars or buses. According to recent research, this stratum of the population already has a similar perception of comfortable temperatures as people from Central Europe. Spending so much time in air-conditioned rooms apparently makes people become less adapted to tropical climates.
Air-conditioning is also becoming more common for the poor. Some 20% of the buildings in Rio de Janeiro’s favelas, as the local slums are called, already have air conditioners. Most of them are second-hand devices. When rich Brazilians buy new air conditioners, they tend to pass on their old ones to domestic servants, who do not mind the great energy consumption typical of second-hand units. After all, the power consumed in favelas is rarely paid for, since the people illegally tap the utility grid.
The main reason for the increase in energy-intensive air-conditioning is that architecture does not take into account the local climate. Neither the shacks of the poor, nor the homes of the middle class, nor the villas of the rich are designed appropriately in environmental terms.
Experts expect electricity consumption to increase in Brazil by 118% from 1999 to 2020. At present, additional output is mainly provided by thermal power plants, implying considerable investment and fuel costs. The trend will also lead to a great increase in emissions, which, so far, had been quite low due to Brazil’s exemplary hydropower share of around 90%.
Architects and urban planners can determine the level of energy consumption for mobility and thermal comfort over the long run. They thus play a crucial role in the development of sustainable, energy-efficient cities.
Some 80% of the population of Brazil lives in urban areas. While the rural exodus has subsided somewhat in the past few years, cities are still very attractive for the rural population. The greater prosperity of city dwellers – be it ever so meagre – entails an increased consumption of resources. On the other hand, by concentrating more people in one place, cities also provide an opportunity to create sustainable prosperity, given proper planning and enforcement. Resource-efficient transport systems – such as metros – only pay for themselves if the population density is relatively high.
Urban planners lay the foundation for a resource-efficient city. If a city concentrates its population in a relatively small space, it makes low energy consumption possible. Cities with a very high population density like Hong Kong have very low per capita energy consumption for mobility. In contrast, the respective consumption in cities that follow the European planning pattern, such as London and Munich, is three to four times higher. For sprawling cities as Los Angeles or Houston in the United States, the figures are even some 15 to 20 times higher than in Hong Kong.
Revitalizing urban spaces
An example for potentially standard setting planning is provided by the “Sustainable Urban Module”, which was developed for a segment of Rio’s old port. The port’s functions are currently being incrementally transferred to a new facility, thus making a large space available right near the city’s centre. The project is part of a study that aims to integrate several aspects of sustainability, especially energy efficiency, in a hot and humid climate.
One essential aspect of the Module is the mixed use of land: parks and leisure areas are close to educational, residential and commercial buildings. An architectural distinction is made between office buildings that need artificial air-conditioning and residential buildings in which a pleasant temperature can be provided by means of natural ventilation. The result is two completely different planning approaches and building types. On the one hand, there are compact, air-conditioned buildings in a densely packed area and, on the other, residential towers that act as individual vertical elements so as not to prevent the natural flow of air between them.
These two concepts are vertically connected in the Sustainable Module. The lower levels offer a conventional urban scenario of lively streets and squares. On the joint roof level above, there is a park that not only offers excellent leisure space but also positively affects the microclimate. The residential towers are then integrated as independent structures within the park. Having intensive parks and green roofs instead of impermeable urban surfaces cools down the microclimate considerably.
Architectural options
According to an analysis by Brazilian scientists, the climate of Rio de Janeiro only demands artificial air-conditioning for 3% of the year. Air-conditioning, in turn, requires great investments. In office buildings, the related costs amount, on average, to 25% of total construction costs. The number of buildings with air-conditioning is increasing in almost all sectors, even though there are some very simple ways of reducing temperatures indoors that would make air conditioning systems obsolete.
For example, brick walls without any plaster are typical of favelas. The dark surfaces absorb sunlight, thus contributing considerably to the heat inside. Housing would become much more comfortable if the walls were painted white, because temperatures inside would drop considerably. Currently, a research project is looking for ways to use “green roofs” to make indoor spaces more comfortable. The initial results are quite promising.
In another project, a low-energy school for 1200 pupils, a number of energy-efficiency measures have been included from the outset of the project. They include appropriate concepts for ventilation, shading, and daylighting, which make sense in the hot and humid climate. Cooling systems based on evaporation are also applied. Special façades guarantee a daylight autonomy of 86% for classrooms during the day. The remaining artificial lighting can be provided with the power from small photovoltaic panels. Thus, an important goal has been met. The energy efficiency of the building was optimised, and renewable sources cover the remaining energy demand. Additionally, a mobility concept was worked up. Pupils are to be bussed to school rather than taken individually by their parents, as is common for this social stratum today. The benefits for the environment and society are considerable.
Another project exploring new paths is the event hall “Circo Voador”. This pavilion for 1400 people does without a conventional air-conditioning system, which would have taken up 20 to 30% of the total construction budget. Instead, the original geometry was modified, allowing for ventilation in combination with a cooling system based on evaporation. This concept reduces energy consumption by some 90% and the construction costs for the cooling system are 94% lower than with a conventional concept.
Paradigm switch
In the 1940s, 1950s, and 1960s, Brazilian architects developed their own tropical modernism that drew the attention of the whole world. Their buildings were largely based on a bio-climatic approach. But in the 1970s, this development was abandoned, probably for various reasons. The military dictatorship drove such architects as Oscar Niemeyer to emigrate. More multinational firms invested in Brazil and their ideas about architecture reflected the international style. Moreover, the increased use of air conditioners misled architects and building owners into believing that they were completely independent of the local climate.
This belief would be acceptable if energy were inexpensive, available in infinite quantities, and did not cause environmental problems. However, since none of these three requirements will be met in the foreseeable future, we must shift paradigms. The new paradigm will strive towards sustainability and strengthen individual identity by means of a holistic architecture taking account of local climates and integrating local elements, possibly even developing them further.
In 1999, Brazil’s per capita energy consumption was less than one fifth of the per capita energy consumption in Germany and less than one tenth the per capita consumption in the US. Like many, if not all, peoples in developing and industrializing countries, Brazilians also understandably want to reach the living standards of Europeans and North Americans. However, if this higher standard of living results in an increase in energy consumption (especially from non-renewable sources of energy), then these countries – and, indeed, the whole world – will be facing a problem almost impossible to solve. Therefore, the Clean Development Mechanism (CDM) should be made applicable to architecture and the construction industry in general. In the context of the Kyoto protocol, the CDM permits rich nations to lower their own carbon emissions at a slower rate if they actively contribute to reducing emissions in poorer countries.
Dr. Michael Laar
has been working in Rio de Janeiro for six years as a researcher, professor, and architect – without an air-conditioner. Since finishing his doctorate at the Bauhaus University of Weimar, he is developing low-energy buildings and sustainable mobility concepts as a freelance architect and urban planner for Latin America and Asia. In cooperation with InWEnt, he his currently presenting the ideas and solutions to a wider public in Brazil.
michael_laar@hotmail.com
http://www.intelarc.com
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