Sustainable cities face challenge of climate change on Caribbean islands

Architect, scientist, professor at the José Antonio Echeverría Higher Polytechnic Institute, and member of the Cuban Academy of Sciences.

Summary: In close connection with climate change, cities need to be more sustainable, and their architecture needs to change, particularly on the Caribbean islands, where there is a growing threat of flooding, heavy winds and the loss of much of these island states’ territory.

As a result of the urbanisation that has taken place in recent decades in developing countries, fundamentally, cities are now the main cause of climate change. They are responsible for 70 percent of CO2 emissions from electric power consumption, the generation of waste, and the demand for transport on the part of their populations, which account for 70 percent of the world total.[1]

Climate change

After a stage of debate and doubt, climate change is now an accepted reality. Attitudes toward it have been evolving, from more or less apocalyptic discourse and pessimistic approaches to more optimistic positions on finding solutions for mitigation and adaptation.

During the Renewable Energy World Conference that took place in Cologne 10 years ago, discussions on the future of the planet were neither all apocalyptic nor predominantly optimistic, and it was acknowledged that despite the fact that CO2 emissions were being reduced at that time, the Earth inevitably would continue warming,[2] and at a faster pace than what scientists had calculated.

At that time, it was believed that the planet’s temperature had risen 0.6 degrees over the previous 100 years and that the amount of rain resulting from human actions had increased[3], and it was predicted that during the following century, the temperature would rise between 1.4 and 5.8 degrees, the sea level would rise from nine to 88 centimetres, and precipitation would increase by five to 20 percent. Some of these changes to the climate would be inevitable, even if CO2 concentrations were re-established in the atmosphere, because what would happen in the next 40 to 50 years had already been determined by past and present emissions.

As part of the consequences of these phenomena, it was predicted at the time that by 2080 the number of people who would suffer from floods would rise to 80 million, and that there would be no water in dry regions. Other effects expected included the erosion of coasts, the reduction of agricultural production, damage to the ecosystem and the impact of diseases like malaria on 290 million people in developing countries – the most vulnerable.

However, it is striking that at the Renewable Energy World Conference that was held in Linköping, Sweden, in 2011, it was acknowledged that the real challenge is no longer climate change; it is the loss of biodiversity and the nitrogen cycle, and the associated risks have been growing.[4]

Solutions that have been sought

The failure of the Kyoto Protocol rendered ineffective one of the possible ways that it was believed, 10 years ago, that climate change could be mitigated, because it has had very little impact on reducing emissions, and contributions by high-emissions countries have been inefficient.

Nevertheless, there is a consensus about the need to increase efficiency in energy use and to promote renewable energy sources and local generation, as well as flexibility and security in supplies. Using as a reference the structure of living beings, one proposal is the necessary connection, through networks, of small-scale generation and combined sources, improving synergy and integration.[5] One of the main challenges is finding a way of placing renewable energy sources on the market and making them competitive, which requires financing.

One issue that was extensively debated at the Cologne conference 10 years ago was, precisely, financing for renewable energy sources, which are very expensive in developing countries. The most important financial instruments used until then in Germany for encouraging the development of these resources were taxes, subsidies and commercial (“green”) certificates.[6]

The United States and China have become the countries with the most installed capacity for eolian, or wind, energy production, after adding 10,000 and 15,000 MW, respectively, in 2009. In addition, between 2004 and 2014, the cost of photovoltaic (solar energy) panels is expected to go down from three to 0.60 USD per watt. In contrast, the cost of nuclear energy continues to be high, and the consequences of the recent earthquake in Japan have dashed hopes that the European Community had placed in that source of energy.

At the Liköping conference in 2011, emphasis was placed on moving toward a fully sustainable global energy system by 2050,[7] based on a possible stabilisation of demand with an ambitious programme to increase energy efficiency. It is hoped that the same will occur with transport demand, so that it will be possible to reduce the absolute use of energy without affecting services.

According to that optimistic scenario, by 2050 it will be possible for 95 percent of the energy consumed on a world scale to come from renewable sources; these would include not just sun and wind, but also bioenergy. It is hoped that by 2050, bioenergy will contribute to meeting one-third of primary energy demand in the world; it will only be necessary to develop new and more efficient technology for its use.[8] Waste, both urban and organic, constitutes a real potential for bioenergy, as do energy-generating crops. Some say this is possible to achieve while at the same time ensuring food security.

However, climate change will also have a negative impact on the use of renewable energy.[9] For example, higher sea levels will affect oil drilling, eolian production, agriculture and biomass on coasts, especially on small Caribbean islands.

Developing countries

Generally speaking, the developed countries try to prevent developing countries from following the same CO2-generating “path” that they followed, but in practice this is very difficult, for a number of reasons. A good part of the developed countries became that way by appropriating the load capacity of countries that now find themselves at a disadvantage, through processes of colonisation and neo-colonisation, and those unequal relationships continue today with neoliberal globalisation. That is why the real foreign debt that should be paid is the one that the rich developed countries have to the poor exploited countries. It is very difficult to consciously select the path of sustainable development when basic problems (food, health, education, employment and housing) remain unresolved, and when there is no access to clean technologies, no “alternative” solutions, and, what is worse, when aspirations aim for the development model that was imposed by the Western world during the process of cultural colonisation.

Historical injustice is reproduced through the fact that poor countries have abundant sources of renewable energy, but they do not have the technology needed for exploiting those sources. Therefore, while the amount of solar energy available (20 MW per person) is much more than what is needed (0.1-10 KW per person)[10], the projection for the future would be to capture it in deserts for use in the most-populated, highest energy-consuming areas. The tendency in developing countries is to connect generating sources to the national network, which means that the future of renewable energy on the planet goes “from regional production to the inter-regional transport of electricity.” [11]

In addition, for the United States of America, the development of renewable energy is a question of national security, which is why applied research is being promoted in this field. During the World Renewable Energy Forum in Denver in 2012, the authorities who participated referred to policies needed for promoting the development of renewable energy sources and their financing, placing a lot of emphasis on managing the transition and on the need for demonstrating economic (not just environmental) benefits of these sources. However, it is significant that at no time was it mentioned that it is necessary to change the lifestyles that are predominant in U.S. society in order to move toward more sustainable development. At that forum, only one representative of the United Nations referred to the problems of developing countries.

Cities and neutral buildings

Connecting energy sources to the national network as a solution for the future is still insufficient. Projections for the years 2050 and 2100 place a priority on sun and wind-generated energy. However, it is recognised that the problem is not just energy technology, but also urban planning, transportation systems, the use of materials and soil, and patterns of consumption.

One of the most hotly-debated issues at the 2011 Linköping conference revolved around “energy neutral cities” and “net zero energy use buildings.” The many different terms related to this objective include “carbon neutral,” which refers solely to greenhouse gases converted into CO2, something similar to the case of “climate neutral,” relative to the influence on climate change from the emissions of these gases. The concept of “energy neutral” is then broader in that the quantity of energy used in a region cannot be greater than what is supplied by renewable sources, and all attention is concentrated on that supply system.[12]

The crux of the matter, in this case, is reducing demand on the one hand through greater efficiency and lifestyle changes, and on the other, by increasing energy production from renewable sources. When these two curves meet (demand and renewable energy produced), that will be the point of energy neutral, which some cities propose to achieve before the year 2050.

To be able to do this, there are problems to be solved and opportunities to be taken, but the process should be monitored, and one good contribution would be for each building to be “energy zero.” For that, recovering on the investment should include non-payment for energy; that is, its consumption free of charge. It is also necessary to increase the use of bicycles or electric vehicles; reduce consumption; and equip buildings with devices for producing clean energy, such as solar panels. This requires a new transitional model of management, in which the municipality or city, the private sector and the final users are equally committed.

During the 2002 Cologne conference, Germany’s experience was presented, specifically in the state of North Westphalia, where the conference was held ­ and which became a major energy consumer after World War II.[13] With the “modernisation of apartment buildings,” they were able to reduce fuel consumption for heating by 20 litres/square metre. In addition, residential areas were reorganised and new “solar settlements” were planned, where 66 percent of the energy consumed came from the sun. By then, new buildings were being designed as solar plants for living while at the same time generating clean energy through the use of photovoltaic systems on walls and roofs, consuming just 1.5 litres of oil per square meter annually.

The use of solar designs for buildings had been promoted in Germany for 10 years with a five percent interest rate[14], under the concept that the marketing of emissions reductions could create an extra source of financing for renewable energy, especially in developing countries. The Japanese, for example, developed an intense programme of photovoltaic solar roofs, and one of their goals was to increase the market to give the industry economies of scale.

Another approach that was championed at the 2002 Cologne conference was that of building façades that operate as regulatory membranes for thermal and visual comfort and air quality, far beyond their purely aesthetic or decorative functions. For a façade to function as a dynamic enclosure, an integrated model must be developed that goes from passive to active solutions, with a decentralised distribution and a control system.[15]

The concept of “zero” is applied not just to energy, but also to air, water, soil and materials, as a way of trying to close all cycles and to recuperate (reuse and recycle) everything possible. Without question, to be able to achieve the concept of “energy neutral” at the level of an entire human settlement or region, the use of urban waste in energy production is decisive, and that requires legislation, taxes, guidelines and objectives.[16] This evolution in practice means going from burying waste (which should be heavily penalised) to recuperating, recycling and reusing it, with the final goal being to reduce its production.

These issues were once again the centre of attention at the 2012 Denver forum, where one topic discussed was the “Architecture 2030” movement launched by architect Edward Mazria in 2006, with a view to achieving zero energy buildings by 2030. The proposal is that it is possible to reduce energy consumption and that each building should be able to produce more energy than it needs if the appropriate design and technology solutions are implemented. In order for that to happen, procedures need to be changed and existing buildings need to be improved.

There are different approaches to the “zero energy” buildings: according to the energy consumed by the building on the site or more specifically its primary energy, according to its exergy[17]as a result of CO2 emissions and its energy cost. In any case, in a graph that compares demand to consumption, it would be necessary to begin by reducing the first.[18]

Buildings consume between 30 and 40 percent of energy and more than 50 percent of primary resources; they produce 30 percent of greenhouse gases and from 25 to 40 percent of solid waste; and they contribute just 10 to 15 percent of the domestic product.[19] Therefore, the main challenges for this sector are mitigating environmental impact and adapting to climate change; a radical increase in energy efficiency and the introduction of clean forms of energy; and satisfying the expectations of clients in terms of health, safety, quality and cost.

In developed countries such as Canada, emerging technologies are used (nanotechnologies, bio-products and others) that can prove more enduring, energy-efficient and environmentally-friendly; information control technologies that make it possible to automate processes for greater energy efficiency; LED lighting systems, and alternative energy sources such as hydrogen. They are also working on developing integrated systems with photovoltaic roofs and high-efficiency energy cells, and they use sensors to improve services in buildings, the health of their inhabitants, and the quality of the air indoors. In addition, they are moving from centralised systems to personalised automatic environmental control which cut energy use by 30 percent in offices.

Building design, passive solutions, shade as a principal strategy, cooling and de-humidification, the integration of photovoltaic energy, simulation and modelling were all central issues of discussion at the 2012 Denver conference. Emphasis was placed on the difference between passive and passive solar architecture, especially the importance of simplicity and the compactness of volume and thermal mass over glass surfaces exposed to solar radiation for heating needs. In any case, what is first needed is to design a passive architectural solution and then to make it active, based on a design that involves the joint participation of architects, engineers and other experts from the very start.

According to what was laid out by Edward Mazria at the Denver forum, it is expected that investment in the building sector, along with conservation in transport, will predominate until 2030, with overall costs totalling less than 2 percent of the gross domestic product, and both of these areas will begin to be recuperated in 2035. However, strong leadership is required for these changes to happen.

Climate change on Caribbean islands

Climate change is not just a future projection; it is part of the present, which is evident from the manifestations that are occurring with respect to the presence of meteorological phenomena that are unusual, especially because of their frequency.

Global warming is making it necessary in cold climates, where the architecture traditionally has been conceived to capture solar radiation and retain heat, to adapt buildings to new and different conditions: the hot summers that are coming. However, the expected rise in temperatures will further aggravate the situation in the warm tropical climates of the Caribbean islands.

Moreover, alterations to rainfall patterns, including longer droughts and extensive rainy seasons, create extreme situations that require adaptation in order to be counteracted. For example, the tendency for accumulation of rainwater that cannot be evacuated in time because of its heavy flow and saturation of the ground, in which case the level rises and produces flooding. This situation can also affect roofs, even when they have an adequate system of slopes, gutters and drains.

Long periods of heavy rain that can be associated with meteorological phenomena such as hurricanes and tropical storms not only generate direct flooding, but also indirect flooding, through overflowing rivers and streams and coastal flooding that result from these phenomena.

Another effect of hurricanes that are becoming increasingly frequent and powerful is the one produced by their strong winds blowing against buildings. This is even more significant in the Caribbean, because of the light, permeable nature of architecture in the wet tropics, although the impact is greater in urban areas.

All of these effects are now being felt. However, the expected overall rise in water levels on the planet could mean the loss of a large part of the lands of island countries, which is why it is the most serious threat of all for the future development of those nations, particularly on the Caribbean islands.

Architectural and urban solutions

The recommendable architectural model for warm and humid climates is more appropriate for low-density rural or suburban areas, where buildings are separated and are permeable, for facilitating natural ventilation, and where they are protected from the sun by large eaves or latticework that diffuses the sunlight, generating the contrast between the light and shade that characterises Caribbean architecture. At the same time, construction materials should be light, with little mass or thermal inertia, so that they cannot retain the heat that has been captured; on the contrary, they should cool off rapidly.

All of these characteristics are recommendable for good habitability in quality indoor spaces, contributing to the thermal and visual well-being of the people who live in them, but they increase the vulnerability of buildings to conditions such as strong hurricane winds.

However, in old cities, at least in the former Spanish colonies, the Mediterranean model prevails, where buildings are divided and have interior patios, thick walls with high thermal inertia and small windows. These characteristics are not in line with design recommendations for warm and humid climates, but they are better at withstanding heavy hurricane winds.

So, what would be the best solution for meeting these two, very different requirements? Neither of the two styles can meet both needs. While it has been shown that the Mediterranean model is not too unfavourable in the hot and humid climate of Havana[20], it is impossible to reproduce it as it was in today’s conditions. Moreover, recent research has shown that the urban model of a compact city should be transformed to make it more sustainable in Cuba’s climate conditions.[21]

In warm and humid climates, where shade, ventilation, lightness and insulation are required, it is impossible to live in solid, massive, closed buildings that would withstand a hurricane but would affect the quality of everyday life. Therefore, buildings normally would have to be shady, insulated, light and ventilated, and also capable of being transformed, so that they could be closed up and withstand heavy winds in case of a hurricane.

Transformation, evolution and adaptability are categories inherent to sustainable architecture. Nevertheless, it has been shown that traditional light buildings can withstand a hurricane if they are well-built, and above all, if special measures are taken when a hurricane is anticipated, to reinforce and secure their components.

With respect to the risk of floods, one traditional solution that continues to be valid today is building on pilings, which, given today’s circumstances, perhaps should be higher. Of course, the selection of a site for constructing a settlement or a building should take this aspect into account.

The most serious threat is posed by the rise in the Earth’s sea levels, especially for poor Caribbean island nations, which do not have the technology to mitigate the effects. Building higher, on pilings, continues to be one valid solution, or building on a foundational infrastructure, which could be a more expensive solution. For some coastal areas of the United States that are routinely flooded, such as New Orleans, proposals are being developed for buildings that can float in case of flooding, and it remains to be seen how feasible such a solution would be for the rest of the region.

With respect to energy, a consensus has existed since the Cologne conference 10 years ago that the most appropriate way to generate energy in developing countries is to use decentralised, small-scale methods that are more democratic and help to create jobs.[22] The biggest difficulty in these cases is financing. Another important problem to address in developing countries is the supply and treatment of water, for which technical cooperation is necessary.[23]

Some traditional techniques for air conditioning in warm and dry climates, such evaporative cooling, are being used with encouraging results in Malaysia,[24] using recycled rainwater and spraying accessories, which are placed on solar protection devices. Other experimental solutions use double roofs with convective ventilation, which allows for natural lighting and prevents solar radiation from entering.[25] Likewise, new and promising solar cooling solutions have been created based on simple and double absorption systems, which were presented at the 2012 Denver conference, but also, and especially, systems that use desiccant liquids, which are appropriate not just for cooling but also for de-humidifying, and which are more effective and easier to implement.

Also at the Denver conference, speakers defended the importance of shade as a fundamental design strategy, even in cold climates, and solutions were presented that ranged from traditional vegetation to dynamic adaptive façades that attempt to imitate the properties of living organisms. In any case, the advantages of exterior shade were acknowledged as allowing for a greater reduction in energy consumption, while interior shade is also beneficial, specifically for attenuating glare. Likewise, contemporary window solutions feature solar protection that is “attached,” sometimes to the interior of a double window.

Like in any other region of the planet, sustainable cities in the Caribbean need to be planned to promote social integration, and to use available resources, particularly urban soil, green areas (including edible landscaping), water and energy. For that, small-scale structuring of units is desirable, with the greatest degree of autonomy possible, so that they can contribute to reducing transportation distances and encouraging pedestrian movement and the use of cycles. In any case, it will stimulate large-load capacity collective transport, travelling in prioritised lanes and with the most efficient technological solutions possible.

Sustainability on the Caribbean islands also requires the stimulation of self-assessment and local identity to be able to hold a risk-free dialogue in a globalised world, and to pass on to future generations a legacy of quality that is superior to what was inherited from the preceding ones.

Final reflections, looking toward the future

Cities have a close relationship with the climate, which is now an indisputable reality. Taking action on those urban spaces to make them more sustainable is one way to attenuate the effects of climate change.

According to the more optimistic scenarios, by 2050 energy demand may become stabilised, 95 percent of the energy consumed will come from renewable sources, and every building will be able to produce more energy than it needs. However, both projections and possibilities for achieving these objectives are different in developed countries and developing countries, particularly on the Caribbean islands.

Climate change is aggravating the thermal situation in the humid tropics and increasing the threat of floods and strong winds, but the most serious impact for the future will be island states’ loss of land.

To adapt to these changes, architecture must be able to change, like living organisms, from an everyday condition of lightness and permeability to an exceptional one of massiveness and resistance, where protection against rain and shade, especially green shade, are essential.

Urban sustainability for mitigating climate change on the Caribbean islands should be planned for social integration, appropriate use of resources, decentralisation, and local identity, on the basis of progressive and adaptive strategies, and this is only possible with a multidisciplinary and participatory approach. (2012)

[1]Mohsen M. Aboulnaga: “Sustainable Cities: Strategy and Indicators for Healthy Living Environments”, World Renewable Energy Congress, Linköping, 2011.
[2]Einsenbeis, G.: “Solar Innovations for Global Sustainability”, World Renewable Energy Congress, Cologne, 2002.
[3]Warrilow, D.: “Climate Change and Policy Issues”, World Renewable Energy Congress, Cologne, 2002.
[4]Thomas B. Johansson: “A New Global Energy Agenda for a Rapidly Changing World,” World Renewable Energy Congress, Linköping, 2011.
[5]Bull, S.R.: “Renewable Energy. Past, Present and Future,” World Renewable Energy Congress, Cologne, 2002.
[6]Fell, H. – J.: “Financing Renewable Energies –Political Frameworks,” World Renewable Energy Congress, Cologne, 2002.
[7]Kornelis Blok. Ecofys, Holland: “Pathway to a Fully Sustainable Global Energy System by 2050.”
[8]André P. C. Faaij: “Bioenergy in a Sustainable Future; Results on Bioenergy in the IPCC-SRREN,” World Renewable Energy Congress, Linköping, 2011.

[9]Lux – Steiner, M.: “Photvoltaics – A Contribution to the World–Wide Energy Supply,” World Renewable Energy Congress, Cologne, 2002.
[10]Thomas B. Johansson: “A New Global Energy Agenda for a Rapidly Changing World,” World Renewable Energy Congress, Linköping, 2011.
[11]Einsenbeis, G.: “Solar Innovations for Global Sustainability,” World Renewable Energy Congress, Cologne, 2002.
[12]Jacques Kimman: “The Road Towards Energy Neutral Cities,” World Renewable Energy Congress, Linköping, 2011.
[13]Vesper, Michael: “Solar Building Policy in North Rhine – Westphalia – a Contribution to Climate Protection,” World Renewable Energy Congress, Cologne, 2002.

[14]Drummond, S.: “New Finance for Renewable Energy: Greenhouse Gas Emission Trading,” World Renewable Energy Congress, Cologne, 2002.

[15]Nolte, C., and C. Otto: “Design Approach for a Dynamic Enclosure within the Building as a Power plant (BAPP),”World Renewable Energy Congress, Cologne, 2002.
[16]Per Laurell.GävleEnergi, Sweden: “A Community-owned Energy Company: Its Role in Renewable Energy and As a Driven Force for Regional Development,” World Renewable Energy Congress, Linköping, 2011.
[17]This is a thermodynamic property that makes it possible to determine the maximum useful work possible of a given quantity of energy that can be achieved through spontaneous interaction between a system and its environment.
[18]Al a Hasan: “Optimal design of Net Zero Energy Buildings,” World Renewable Energy Congress, Linköping, 2011.
[19]Morad Arif: “Towards Near-Zero Energy and Carbon Emissions in Buildings and Communities: Overview on R and D and Innovation Projects,” World Renewable Energy Congress, Linköping, 2011.
[20]Alfonso, Alfonso, and others: “Por el rescate de la tradición”, Arquitectura y Urbanismo, No. 2, 1989, pp. 2-7.
[21]González, Dania, Aprovechamiento del suelo y ambiente interior como variables contrapuestas para la sustentabilidad de la vivienda urbana, Editorial CUJAE, 2008.
[22]Höhn, Bärbel: “Biomass Contributing to the Future Energy Generation,” World Renewable Energy Congress, Cologne, 2002.
[23]Behler, Gagbriele: “Education on Energy and Environment – a Global Challenge,” World Renewable Energy Congress, Cologne, 2002.
[24]Rao, S. P.; Ariffin, P. A. R., and S. N. Inangda: ”Evaporative Cooling of External Walls and its Influence on Indoor Air Temperatures in an Ecuatorial Climate,” World Renewable Energy Congress, Cologne, 2002.
[25]Waewsak, J.; Hirunlabh, J.; Khedari, J., and Zeghmati, B.: “A Bio–climatic Roof for Hot and Humid Climate Design Approach,” World Renewable Energy Congress, Cologne, 2002.

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