Bioclimatic architecture

1) Introduction: what is meant by bio-architecture

La bio-architecture or bioclimatic architecture favors the use of materials and techniques that allow energy saving and that do not pollute and do not damage human health. Bioarchitecture is in fact a concept linked to the awareness that technological processes have a limit and the environment cannot be exploited endlessly, since the resources of the territory are not inexhaustible.

Bioarchitecture was born in Germany towards the end of the Seventies, after the global energy crisis of 1973. The vast world of building production, and not only, began to take into consideration some measures, used since the past and fallen into disuse, such as solutions for ventilation, shading, cooling, thermal insulation, reduction of heat loss, natural lighting, etc.

Bioarchitecture aims to design in a sustainable way, experimenting with new systems, such as the use of solar energy in homes, and using materials that tend to limit environmental impact, such as wood, stone, plaster, or in any case natural products rather than chemical ones.

When designing a bioclimatic building, some considerations must be taken into account:

• energy saving must be non-renewable, reducing the release of pollutants into the environment, greenhouse gas emissions. All this can happen with the insulation of the walls: in this way the building can acquire heat during the winter through external glass, while in the summer season it must have natural air conditioning thanks to the insulation of the building itself;
• we must try to save drinking water by creating a double water network: one fed by the city aqueduct, and one fed by rainwater, which is collected and purified;
• improve comfort inside environments by reducing pollution;
• Recyclable materials are preferable, which require little energy during production, and are ecological during processing; therefore, alternative and biocompatible construction materials should be chosen, before choosing materials that are easily available on the market.

2) Characteristics of a bioarchitecture project

Bioclimatic architecture and green architecture are architectural design methods that seek to minimize energy waste in the environment through the use of specific and particular technologies that promote human comfort.

Bioclimatic principles are the same construction methods that were used in the past, when the few energy and technological resources that were available were used. All this changed during the period of industrialization, when more modern methods began to be used; but all these changes lead to the construction of buildings of very poor quality, in order to satisfy all the housing demands, with consequent problems of conservation and maintenance of the same, thus leading to the damage of environmental pollution.
Today the issues to consider for new constructions are related to energy saving, saving on building maintenance costs, minimizing polluting resources, good levels of comfort required for a better quality of living, and increasing renewable sources.

The principles of bioclimatic architecture

Building following the principles of bioclimatic architecture means:

• use green building;
• create an ideal climatic environment inside the building;
• reduce indoor pollution;
• control the use of drinking water and avoid wasting it;
• check the air quality;
• use technologies that exploit renewable and low environmental impact energy.

Building according to green building techniques means building using ancient construction methods, while at the same time using modern techniques, using natural materials, constructing buildings that allow thermal insulation and heat conduction, which can therefore “breathe” retaining heat but avoiding humidity.
To promote a good microclimate within an environment, heating techniques must be used that allow a regular degree of radiation and low heat convection; temperatures must be kept high on the radiant surfaces and low in the environment to ensure an acceptable level of humidity.

To reduce drinking water consumption, you can use various systems:

• the use and accumulation of rainwater in special containers and deposits, which will then be purified for use in the domestic environment;
• the creation of paths such as small streams and ponds, where a naturally humidified environment can be obtained thanks to the evaporation of the water itself.

To control air quality, attention must be paid to the methods of air distribution, considering particular and specific systems, to the ventilation of large spaces, and to the thermo-hygrometric comfort of the building.
To make the most of solar radiation, buildings must be designed to ensure good orientation, with balconies and windows facing mainly south to accumulate heat, using techniques that provide for passive exploitation of solar energy.

Another key point is the use of renewable energy, namely: use of solar thermal energy, to produce domestic hot water, photovoltaic solar energy, to produce electrical energy and wind energy, which is transformed into mechanical energy through wind generators.

3) Principles for good design

3.1 Exposure and sunshine

A correct distribution of interior spaces is necessary to make the most of daytime solar energy and for the activities that are carried out daily inside buildings. Usually the living area, where you spend most of your time, is exposed to the south-east and south-west, since these are the sunniest sides; the sleeping area, on the other hand, can be oriented preferably towards the north-west and north-east, where less solar radiation reaches, as well as the passageways and corridors. To prevent rooms exposed to the east and south from overheating, you can use protections and solar screens, which can be fixed or mobile and therefore adjustable.

Facades oriented to the south-east and south-west have a small variation in solar energy intensity throughout the day, so radiation is continuous throughout the year. Facades exposed only to the south are cool in summer and warm in winter. Facades to the east and west are cold in winter and warm in summer, so they vary greatly throughout the year.

3.2 The lighting

Daylight, on which natural lighting depends, is to be considered linked to the characteristics of the light source, i.e. the celestial vault, depending on its latitude, day and time, and atmospheric conditions. Given this premise, it is not possible to predict with extreme precision the illumination inside a room at a given time of day. We refer to the “daylight factor” to measure the quality of the environment from the point of view of lighting, which provides us with the percentage of natural light inside a room, but does not actually provide us with reliable data on the real illumination; this factor does not depend on external lighting, since it refers to the atmospheric conditions of the celestial vault excluding the contribution of direct radiation. The daylight factor is used during design to calculate the dimensions of transparent openings, properties of the materials of such openings, and the reflection characteristics of floors, walls and ceilings.

Natural lighting is fundamental because it influences domestic and environmental comfort and is an essential element for bioclimatic design. In fact, an environment receives direct sunlight, light from a clear sky and diffused light. Naturally, openings must be placed in strategic points to make the most of the light flow and uniform distribution must be guaranteed, so that there is a correct proportion between light and shadow.

Artificial lighting is also very important. Three types are considered:

• direct: the light directly illuminates the objects of interest;
• live: the light is directed towards the ceiling via screens and then sent back into the room by diffusion;
• semi-direct: has characteristics in common with both direct and indirect light.

3.3 Thermal insulation

It is necessary to ensure adequate thermal comfort within an environment and this depends on the microclimatic conditions present in a natural or artificial way, therefore: - the temperature; – the hygrometric degree; – the average radiant temperature of the surfaces; – the movement of the air. These parameters must be maintained at specific levels so that a thermal equilibrium is maintained within the human body.

First of all, the building's construction elements must ensure ideal thermal comfort, through the appropriate layout and orientation, as previously mentioned. All this must be integrated with specific systems and the materials used also play a fundamental role, preferably bioclimatic and in compliance with modern green building techniques. Thanks to the continuous improvements in thermal qualities, it is also possible to have an economic advantage, with a reduction in energy consumption of up to 30% for heating and cooling. 

3.4 Sound insulation

Noise sources can be due to vehicular, air, railway traffic, external or internal systems and equipment of the building. Urban noise is the cause of considerable disturbance within the domestic walls, and must be reduced. Considering the bioclimatic point of view, the parameters of sound and noise that adopt fundamental importance are the acoustic intensity and the frequency spectrum.

A sound wave, when it encounters an obstacle, such as a wall, is partly reflected, partly absorbed and partly transmitted because it manages to overcome the obstacle; transmission can occur through the diaphragm, that is when the sound enters as a vibration of the wall itself, through diffraction of the wave through cracks in the building materials, and simply through the propagation of the wall.

4) Materials used in green building

In green building it is preferable to use low-emission materials; naturally other aspects must also be considered, including installation techniques, finishing processes and maintenance of the materials themselves. Both of these elements must be taken into consideration, since it often happens that the polluting causes are due more than anything to incorrect installation and unsuitable use of green building material.

It is also essential to evaluate the age of the building, since the older a construction is, the more biological contaminants will have to be used.
Therefore, before the intervention, the designer will have to estimate the conditions of the products before their production and request their quality certification.
Unfortunately, traditional building materials are used in construction no more than 20%, while for the rest, artificial, cheap but less sustainable products are used.

Products of mineral origin such as bricks, ceramics, stones and plaster are non-polluting and maintain their qualities over time.
Natural and recycled materials, which are available on site, are preferable, as this also limits waste and transport; furthermore, they can be recycled and therefore easily reused.

Let's try to distinguish a natural material from a sustainable one. There are materials that, even if they derive from other natural ones, end up being processed with polluting substances, thus losing their natural qualities. A sustainable material compromises the surrounding environment very little throughout its life cycle; a material is more sustainable the less energy it wastes, starting from the extraction, processing, packaging, transportation phases, up to its use, consumption and disposal.

In 1989, the European Community issued Directive No. 106, which lists the requirements for building materials so that they can circulate freely in Europe. One of the fundamental requirements is called “hygiene, health and environment”: the building must not cause any harm to health in general and must not cause toxic gases and emissions of dangerous radiation or pollution.

Materials are mainly divided into three groups: mineral, vegetable and chemical.
The first group includes siliceous materials, such as glass, sand, gravel, pebbles, granite, stoneware, clay, marble and salt rocks from which gypsum is obtained; then there are also minerals such as iron, cast iron, steel, zinc, aluminium, copper and lead.
The group of plant materials includes wood, oils and various reeds used in construction.
Chemical materials include paints, PVC, polyesters, resins and synthetic insulators.
From an ecological point of view, brick is certainly the most natural material, followed by wood and concrete.

5) Bioclimatic systems

In order for bio-architecture to contribute to the qualitative improvement of our life inside buildings, the climatic aspect of living must also be considered.
The environment we live in changes depending on the temperature, the speed of the air, the chemical composition of the air, etc.

It is necessary to find a balance between these factors to allow excellent living comfort. Systems also contribute, which allow the climate to vary inside a building.
Simple plumbing and electrical systems are preferred to minimize energy waste. As for heating systems, those that spread heat by radiation and not by conduction or convection are preferred to minimize any air movements, with polluting dust.
Let's now see which systems are used in green building constructions.

5.1 Heating system

For the heating system it is preferable to use machines with direct and induced radiation operation; this occurs through some systems:

• radiator system, with boiler and radiators, preferably running on gas fuels such as methane;
• “skirting board” system: it is the same as the radiator system, the only difference is in the bodies
• heating elements, which are ribbon-shaped and positioned in correspondence with the skirting boards. The heat is transmitted to the walls, which in turn redistribute it by radiation to the surrounding environment;
• stoves with high thermal inertia are not real heating systems, since they are made of refractory stones and work by radiation; they are usually not able to heat large rooms, but can only bring heat to some rooms;
• warm perimeter wall system has only radiant operation. The heat is diffused from inside the walls, where hot water or hot air circulates;
• central heating system consists of a heating machine, located in the center of the building, and can also be developed on several floors. The heat source is a fireplace or a sauna room located on the lowest floor of the building; from this room the heat spreads by radiation to all the other rooms.

5.2 Electrical system

The electrical system must function properly without creating electromagnetic disturbances.
In order to ensure the right conditions for correct green building design, it is recommended to:

• make open circuits;
• insulate the electrical conductors that support refrigerators and heating plants by means of a metal sheath connected to the earthing system;
• place the meter outside the building outline;
• insert special filters to eliminate disturbances caused by household appliances and external systems.

Low voltage and direct current systems are the most ecological because they do not generate pathogenic fields and because they can be powered by alternative sources (photovoltaic cells, micro hydraulic and wind power plants).

5.3 Plumbing system

The plumbing system must not cause mechanical vibrations, heat dispersion or emit dust harmful to humans, so that it is built in a sustainable manner. The system can be made suitable by placing the pipes in specific compartments away from prolonged parking areas, insulating the pipes with natural materials.
In a perfect green building context it would be ideal to use rainwater recycling systems.