The focus of this video is climate change. We will quickly see the link one can make between urban form, between urban spatial systems and climate change. To begin, we must remember a few things, which is that urban planning is not an autonomous activity, but is at once dependent on demographics, economic changes, political factors, technological progress and, very recently, it is dependent on climate change. This is what we'll see. Now, what are the types of effect? There may be an elevation in temperature. There may be an increase in sea level. One can also have increased river levels or an intensification of rain phenomena. Finally, an increase in natural catastrophes: tsunamis, periods of flooding or drought. This chart is interesting because it shows the types of effect and finally their relation to different human activities. High winds, an increase in high winds does not have a direct effect on agriculture or habitat. On the contrary, in transportation, if we consider air travel, there may be a direct impact. Heavy rainfall may not necessarily have a direct bearing on the whole of human activity. However, without doubt it does on agriculture. And in this graph we can see that ultimately it is agriculture which is subject to nearly all these types of effects. The same with transportation. There are domains where these climate changes will have little effect, and other domains where the changes will be greater. So, when discussing climate change, there are two attitudes on these changes-- Mitigation and Adaptation. Mitigation seeks to reduce the effects and adaptation tries to adapt to them. So while on the one hand I look to reduce rainfall, and flood frequency by reducing, for example-- because there is a direct link to energy consumption-- so I reduce my consumption and with this I will reduce the effects of climate change. On the other hand I say, okay, I will adapt to these changes, and provide technological structures which allow one, finally, to live with these conditions of flooding, drought, of high winds or incessant rainfall. So, with mitigation one tries to reduce, perhaps to begin with those on compact cities. With an urban mix, we will favor public transport, promote walking. We've seen just now in this schematic that there is a direct link between urban density and energy consumption, so one seeks to reduce this energy consumption, and adaptation, this urban sprawl. It is this diffused city which, ultimately, is the model to use as it favors ground absorption in the case of rainfall or flooding. It favors air circulation in the case of pollution, at the same time diminishing the number of pollutants. Therefore depending on the strategy one adopts, to reduce or adapt to these effects, the urban forms will not be the same. On one hand we have the compact city, and on the other the diffused one. Since we're talking about density, about densification, in other words attempts to reduce, or the mitigation, to reduce the effects of climate change, we must first determine what we will measure. Are we talking about gas? Are we talking about CO2? When we wish to say there is a density, what is its metric? What measure is used? Next is the question of low- and hyperdensity. Low density is very energy costly, while hyperdensity, in the same way, is also very, very energy costly. There is without a doubt an optimum which lies between a too-high density and a too-low density. And while we speak of density, we must also speak of the social question. What does it mean to live in an extremely dense city, in social terms? When it comes to climate and humidity levels, we will have different answers depending on urban forms. We know that humidity makes heat even more difficult to bear, and that often when we find ourselves in zones where natural disasters are more or less common--flooding, storms-- it is in tropical zones where there is high heat and high humidity. So the challenge is to find a pattern, an urban form which addresses the issue of both heat and that of humidity. First off, in very hot zones we will try to reduce the heating effect of the sun with urban and architectural elements. We will try to achieve a maximum natural ventilation in the street or in the home. And in the end, the individual home, in a hot and humid climate, can be a solution. We'll start with the individual villa, the single home, because it is increasingly disparaged, in a certain number of cities because it makes up the endless peripheries of American cities and, increasingly, European ones, and is extremely energy consumptive and on the move, as an energy equally and in principal, today, where the tendency is increasing to criticize the individual home, the villa. But, if we return to a hot and humid climate we can question it might be one of its solutions, or one urban form which can respond to all its criteria. Finally, narrow, tall buildings are another solution, for, ultimately, the less the sun's impact, the more one can avoid this connection between humidity and sun. Let's take a look at high winds. A compact form will have the greatest resistance. Mid-height buildings, since low-level buildings will not resist and the higher ones will pose a certain number of problems, so the skyscraper is not very appropriate, for it will have an acceleration effect on the wind between high rises, and neither is the low individual home appropriate, for it has a funneling effect. High density allows for a reduction in the effects of wind. And finally, the effects dependent on street orientation. If your street extends in the principal direction of the wind, it will have an accelerative effect, whereas if one is perpendicular to this wind direction, one will be protected from violent winds. We can also see, when speaking of winds and most notably their urban forms, the urban response will not always be the same, and suddenly, if we combine the effects of heat, humidity, and violent winds, we will realize that we have no more urban form which will allow us to respond to all this. Let's look at yet another example. Flooding, the increase in sea levels and the urban form. The ground should be able to absorb excess water. We spoke of this just now. So in the end the more natural surfaces, the more I am diffused, the more my urban form can allow the absorption of excess water. Let's limit once and for all paved surfaces, or asphalt surfaces, any sealed surface so that while one speaks, particularly about flooding, one can try to take into account vast territories, non-urbanized territories which can be utilized as reservoirs to act as temporary buffer zones so that the water can be stored upstream from the city, rather than in its interior. And at the same time, of course, the question of flooding quickly depends on the question of the morphology of the site, of the land forms, flat or sloping, which clearly have different responses to flooding. Pizarro, in 2010, proposed a matrix, a matrix where one will see these diverse responses, when speaking of high temperatures, of strong humidity, violent winds and flooding, and for each of these effects one can ask what percentage of ground cover, of the distance required between buildings, the median height of buildings, the templates, the spaces, the topography, the quality of sunlight. In sum, a whole series which I will leave for you to read, but one can continue like this, in graphic format, to have percentages, knowing the more one has, for example, a high humidity or strong winds, the more the ground cover should be minimal, by covering I mean asphalt, a covering which does not allow the passage of water, so at all cost this percentage of ground cover must be reduced. So there you have a brief description of some of the effects, some of the responses to urban form, which is to say, when we continue, that urban form is clearly dependent on climate, and on context, and that the response to climate-- and I'm speaking not of climate change, but of climate in general--- that the responses should be different if one is in a tropical, humid climate, or a continental dry one. So for each type of climate there are different responses, which makes it so that for each climate zone one should have different planning. What we will soon see, is how our planning should respond to this context, to this particular context, and how it should respond specifically to the context of climate. We have lost this idea of an architecture, a bioclimatic urbanism decades ago, abandoned in the name of modernity, in the name of aseptic air in commercial centers, air-conditioned, regulated, but today we must question this model, which they try to place everywhere, versus a model which will be contextualized, with a planning that will not be made except in a precise context with its own specifics. In the end, while we're speaking of, and we'll conclude here, climate change, it is impossible to view it from a local perspective. It must be seen from a global perspective. And this without a doubt poses a challenge to a certain number of types, democratic and participative steps,
