Bioclimatic architecture

Bioclimatic architecture consists of the design of buildings taking into account climatic conditions, taking advantage of available resources (sun, vegetation, rain, wind) to reduce environmental impacts, trying to reduce energy consumption. energy. Bioclimatic architecture is closely linked to ecological construction, which refers to structures or construction processes that are responsible with the environment and use resources efficiently throughout the life of a construction. It also has an impact on the healthiness of buildings through better thermal comfort, control of CO₂ levels indoors, more lighting and the use of certified non-toxic construction materials. by environmental declarations.

A bioclimatic home can achieve great savings and even become fully sustainable. Although the construction cost of a building of this type may be higher, it can be profitable, since the increase in the initial cost can be amortized over time by reducing operating costs.

Rural house in Galicia, recently converted into urban housing

Contemporary bioclimatic Architecture, Coco Island Monitoring and Control Center, Costa Rica by Ibo Bonilla

Background

to the climate, needing as little energy support as possible and, by trying to change small details, they have been finding appropriate solutions to the general problem of the climate; Examples of this are the whitewashed houses in Andalusia against the houses with the natural color of the material from the northern plateau of the peninsula, or the south-facing facades in the Northern hemisphere, in order to take advantage of the sunlight. Also the example of the chalets in the Alps or rural houses in many parts of the world, as can be seen in the image, can be considered as excellent adaptations of rural life to the climate with thermal stations throughout the world. In these two types of dwellings indicated, the stable on the lower floor served as a heater in winter (due to the heat given off with the fermentation of the straw and manure or compost) and the animals were taken out in summer to graze, then serving as moderate thermal insulation.. In addition, the second floor or attic originally served as a haystack or hayloft during the winter, which insulates the living area on the first floor from the outside cold. And in Galician rural houses, the exterior access to the first floor where the rooms are located is traditionally designed to avoid frequent passage through the stable.

In the same way that a bioclimatic building seeks to adapt to the climate of the place, users must also have an adaptive behavior. It implies that there is a double adaptation, climate and culture, which leads to a change in the behavior of individuals and over time in cultural habits. Given that contemporary society has adapted to a technology that simplifies the operation of buildings, a bioclimatic building is not always appropriated by its inhabitants.

A triple resistance appears: developers who do not wish to spend more, users who do not understand the bioclimatic concept to operate their building, and architecture professionals and schools that privilege formalism over adaptation to the climate.

General information

• Bioclimatic architecture is a type of architecture where balance and harmony with the environment are a constant. It seeks to achieve a certain level of thermal comfort, taking into account the climate and conditions of the environment to help achieve the interior thermal comfort by adapting the design, geometry, orientation and construction of the building adapted to the climatic conditions of its environment. It plays exclusively with the local characteristics of the medium (relieve, climate, natural vegetation, direction of the dominant winds, insolation, etc.), as well as design and architectural elements, without using mechanical systems, which are rather considered as support systems. We should not forget that a large part of the traditional architecture already worked according to the bioclimatic principles: south-facing windows in the cold climate regions of the northern hemisphere, the use of certain materials with certain thermal properties, such as wood, stone or adobe, the floor coat, the stall in the Mediterranean houses to keep the interior fresh in summer, the location of the villages, etc. The bioclimatic architecture is, in short, an architecture adapted to the environment, sensitive to the impact it causes in nature, and that tries to minimize energy consumption and with it, environmental pollution.
• A bioclimatic house does not have to be more expensive than a conventional one, but those built in temperate climates have shown an overrun of 5 to 15%. It does not need the purchase or installation of mechanical air conditioning systems, but it plays with the architectural elements always to increase energy performance and achieve comfort naturally. To this end, bioclimatic design represents a set of restrictions, but there are still degrees of freedom for design according to the taste of each one. The bioclimatic architecture takes into account the conditions of the terrain, the tour of the Sun, the air currents, etc., applying these aspects to the distribution of the spaces, the opening and orientation of the windows, etc., in order to achieve an energy efficiency. It is not to invent strange things but to design with existing ones and to know how to make the most of the natural resources provided by the environment. However, this does not have to condition the appearance of the construction, which is completely variable and perfectly consistent with the trends and design of a good architecture.
• Bioclimatic design is based on the climate analysis of the study site, for this it is necessary to process the main weather data (temperature, humidity, rainfall, wind, radiation, among others) using graphics, maps, or typical projections of solar geometry. It is also important to take advantage of the various tools developed by the main researchers of the topic (Baruch Givoni, Viktor Olgyay, Mahoney, etc.). These tools such as the bioclimatic letter or psycrometric, allow to evaluate climate data with the temperature considered as "confort" and obtain design recommendations, such as ventilation, use of thermal mass, use of evaporative cooling, etc.

Adaptation to temperature

The galleries (balconies and glazed windows) of La Coruña, a typical example of the use of insolation for the natural heating of the houses in winter

It is perhaps at this point where it is most common to influence when talking about bioclimatic architecture. The most usual thing is to make the most of the thermal energy of the sun when the weather is cold, for example for heating and domestic hot water. Take advantage of the greenhouse effect of crystals. Have minimal heat loss (good thermal insulation) if there is a heating element.

When the weather is warm, the traditional thing is to make wider walls, and have the roof and the facade of the house with light colors. Putting awnings and special glass such as double glazing and having good ventilation are other solutions. In the case of using a refrigeration system, isolate the house. Having a large deciduous tree in front of a house that blocks the sun in summer and allows it in winter would also be a solution.

Orientation

• With a orientation of the glazed windows to the south in the Northern Hemisphere, or to the north in the Southern Hemisphere, more solar radiation is captured in winter and less in summer, although for the warmest areas (with average temperatures above the 25 °C) it is substantially more convenient to place the glazings in the opposite sense, that is, giving the back to the equator; of this way in the summer only

Sunlight and sun protection

• The windows with adequate sunscreen, lengthened vertically and placed on the inner face of the wall, let less solar radiation enter in summer, avoiding overheating of sunny premises.
• On the contrary, this effect is not beneficial in cold places or during the winter, so, traditionally, in cold places the windows are larger than in the warm ones, they are located on the outside face of the wall and tend to have glazed viewers, to enhance the beneficial capture of solar radiation.

• Solar protection devices:
  • the alero: is the horizontal plane of sun protection, on the north facade (south hemisphere) or south facade (north hemisphere) allows co
  • oblique vertical parasols to the facade: in western facade or east facade. In these directions, the solar incidence is at low altitude, so the aleros are not effective. The placement of these screens at 45o allows solar penetration in winter and the incidence of the sun can be controlled in summer.
  • exterior blinds to the window; the most effective shade is achieved with these devices, in warm weather it is very important that the sun does not transcend the glass, so it should always be protected outside, because otherwise the window will work as a flat solar collector, leaving the heat inside the place. On the previous ones they have the inconvenience that they are not passive, you have to close at the time the sun gives in the window and open when it does not give, especially at night to allow cooling by ventilation with cooler night air.

Port of Willemstadt, on the island of Curacao

• The port of Willemstadt shown in the image, on the island of Curacao, is an example that opposes the bioclimatic architecture. The roofs tilted to avoid the accumulation of typical Dutch snow and the relatively small and closed windows contrast with the warm climate of the intertropical zone, where it is essential to study ventilation through windows directed mainly towards the east and northeast, to take advantage of the smooth winds that blow throughout the year (this idea refers to the Northern Hemisphere; it would be different in the southern hemisphere). However, this apparent problem is justified on tourist grounds and is controlled by the use of air conditioning, very important and even necessary by the enormous amount of tourists and the fundamental use of buildings for commercial purposes.
• One of the main objectives of bioclimatic architecture is to offer optimal air conditioning and ventilation from proper management and regulation of solar radiation as well as natural air circulation. This type of architecture is an upward trend supported by increased environmental awareness, also in the exterior spaces of the houses. It is known as the bioclimatic pergola that solar protection system capable of naturally regulating the temperature of the area it covers and the solar radiation it receives, while providing protection against the rain, the wind and any other weather inclemence.

Thermal insulation

• The thick walls slow the temperature variations, due to their thermal inertia.
• The buried or semi buried buildings take advantage of the thermal inertia of the surrounding land, stabilizing the thermal oscillation, for example, the thermal variation that occurs between cold mornings and hot afternoons.
• A good thermal insulation avoids, in the winter, the loss of heat due to its protection with the outside, and in summer the inlet of heat.
• One of the materials with better insulating properties is air. Due to its low thermal conductivity values, the use of air chambers is used to interrupt the thermal flow between the interior or the exterior. However, these air chambers are more effective when they have small dimensions, because they limit the convective air movement that can transfer heat from one face to another. A good example of these reduced cameras is the EPS (polystyrene) which contains small air bubbles trapped.
• In the houses with tilted roof or two waters of the temperate zones, a ceiling can be built that encloses a superior chamber in order to isolate the house from the excessive heat of solar radiation in summer and the cold of winter. It is the case of Swiss chalets whose façade is heading south to take advantage of solar radiation during the winter and has a top floor serving as a barn or hay store that has good insulation properties during the winter. Having the rooms of the house on the first floor and the stable on the ground floor, the villa works as an admirable example of bioclimatic housing as the stable produces a kind of natural heating that serves to heat the house on the first floor. In the time of heat, the livestock is taken to pasture in the meadows and when leaving the stable free, it allows a ventilation of the same that serves to refresh the house. Neither the attic or barn has straw or hay during the summer, so it protects the housing from excessive solar heat. The exterior staircase of access to the house (typical in the Galician farms and farm houses and many other parts) aims to access the house without disturbing the livestock and other pets.
• Infiltration is the entrance of air from outside by phenomena or uses in principle not controlled, but which affect or are assumed for ventilation, for example, gates or diffusion through certain surfaces.

Cross ventilation

• The temperature and pressure difference between two rooms with opposite orientations generates an air current that facilitates ventilation.
• A good ventilation or quality of the interior air is very useful in wet warm climates, without mechanical cooling, to maintain an adequate hygrothermal comfort.
• To properly design the ventilation in living spaces, you need to know the direction, speed and temperature of this. For this the climate data of each study site are used, these can be annual, monthly and even timetables. It is important that these data be standardized, i.e. the average data collected for several years (at least 10).
• Ventilation can also be used not only to cool a space as if used in combination with water bodies (sources, ponds) it is possible to increase the humidity of the air, being this technique highly appreciated in dry warm climates.

Integration of renewable energies

By integrating renewable energy sources, it is possible that all consumption is self-generated and non-polluting. In this case, we are talking about buildings with 0 emissions. It can even generate more energy than consumed —which could be sold to the grid—, in which case we are talking about energy plus buildings.

The most used sources of renewable energy are wind energy, photovoltaic solar energy, solar thermal energy and even geothermal energy.

Inadequate architecture from ecological or bioclimatic points of view

Buildings built with government funding to be inhabited by civilians as a subsidy program in Playa Grande, state Vargas, Venezuela.

Throughout today's society, there are numerous examples of incorrect or contrary use of these architectural principles, both in design and construction. In Venezuela, a social subsidy program financed by the government, in which structures are built to be inhabited by low-income families (the image shows a set of structures built in 2011 in the State of Vargas) gives us an example. Taking into account that it is located in an area with a high population density, a very limited urban area, a climate of high temperatures, immediate proximity to the sea and little arboreal vegetation, in addition to a soil characteristic of coastal areas with arid characteristics and with materials of high thermal conductivity (See metal downspouts for garbage and small rooms for the same), can cause serious problems of thermal comfort inside said homes.

We can see that the buildings have a very small number of windows with little surface area, without balconies or other types of ventilation doors; In addition to this, they are relatively small, and are located in the most superficial part of the walls, so they receive a large amount of solar radiation during daylight hours and at the same time do not allow sufficient air access to ventilate and dissipate the sensation of high temperatures; Although the color of the structure is apt to somewhat limit the absorption of solar radiation, it is still too dark and a suitable construction material must also be used. The lack of vegetation, especially the lack of tree vegetation in the pedestrian movement area, causes discomfort and fatigue due to exposure to the sun; The fact that there is no vegetation at all produces a hostile environment sensation and the wind in any direction can generate clouds of dust and earth that penetrate the apartments closest to the ground.

In addition, the proximity of the buildings increases the sensation of heat and generates a source of high temperatures; the use of asphalt for vehicle transit areas absorbs solar radiation and immediately emits infrared radiation that greatly heats the air at ground level.

Among the imprudence in relation to bioclimatic architecture, the following can be highlighted:

• Climate incompatibility. This may be due to negligence in the forecasting of climate factors obtained through the previous climate study. This directly affects the type of materials used and the design of the structure.
• Lack of ecological design and use of space: The fact that there is no vegetation as a building element is incompatible with a sustainable environment, in addition to inadequate use of space, which could be distributed optimally and equally.
• Lack of urbanism suitable to be inhabited by human beings: The construction of a concentration of structures of this type, through a similar design and bypassing so many aspects in relation to the environment, makes it a practically hostile area to be inhabited in the long term by any family.