published on 4 November 2009 in energy
A look to the past
At present, it is more and more difficult to assure the comfort standard which our society provided herself in these last years. The current tendency to equip our buildings with air conditioning systems for warm and cold climates contradicts the most basic rules concerning energy saving and environmental pollution. During the first century B.C., Vitruvio wrote in his De Architectura, Liber I the architectural principles, showing also the structural parameters, where inner and external spaces, building system and materials create a consistent whole with the environment and the climate.
The traditional or vernacular architecture gave a lot of attention to the environment: towns were placed according to local climate, while the houses were perfectly integrated in the land, and from this land they could obtain whatever they needed. At those times, when it did not existed neither radiators nor air conditioners, when we did not have the modern aqueduct or domestic water distribution systems, the inhabitants were used to build their own houses according to the characteristics of the land and of the local climate.
For instance, in warm and dry areas, men were used to build their houses with special devices: the shape of the roof was functional to the collect of the precious rainwater, convoyed in proper cisterns , while creating just small windows, or even none, was useful to prevent heat, and the building materials were all taken from the surrounding environment. In Italy, we can admire different examples of traditional architecture: the trulli of Alberobello, the dammusi of Pantelleria, the barrel houses on the Costiera Amalfitana, the town of Matera, the South Tyrolean mountain chalets, etc.
Even if today we can’t return to the traditional architecture, we are able to notice the design and building rules of these ancient houses, learning how to respect the climate and the season change, the historical characteristics and, in the end, the needing of the modern society.
Bioarchitecture and bioclimatic
Today, we see the common tendency to confuse the bioclimatic architecture with the bioarchitecture. To tell the truth, these words mean different concepts. The bioclimatic architecture is a kind of architecture that satisfies the comfort requirements with the passive control of the microclimate of the house, minimizing the energy consumptions and maximizing the efficiency of the thermal exchanges between the building and the environment, through a correct choice of the building and structural characteristics, of the building materials and the placement of the windows. Bioarchitecture is not a modern invention: it takes inspiration from the traditional architecture that, as seen before, has always been adjusted on the local climate. The demographic growth and the consequent expansion of the building industry caused the abandon of the traditional building art, and the “globalisation” of the construction techniques. The increasing requirement of focusing on the energy saving, on the recourse to renewable sources and to the choice of ecological building systems caused the current rebirth of the bioarchitecture.
Bioarchitecture is the architecture branch that concerns the planning of buildings based only on not harmful materials, on building technologies unable to damage health and environment. Bioarchitecture, very respectful of the sustainable principles, has to integrate the buildings in the environment, satisfying the current generations needing without compromise, with an indiscriminate consumption of the existing resources, next generations’ necessities.
Here we have some of the basilar principles of the bioarchitecture
- to optimize the relationship between the building and the surrounding context;
- to privilege life quality and human psycho-physical well-being;
- to preserve ecosystem;
- to use the renewable natural resources (water, vegetation, climate)
- not to provoke harmful emissions (smokes, gas, drainages, waste)
- to use ecological materials and technologies.
Main objective of the bioarchitecture is the respect of men’s needing, together with the protection of the environment.
The heat pump
The heat pump: an useful system to save energy
Today, the improvement of living standards in the working environments and in the houses weighs a lot upon the civil energy consumptions. In Italy, the air conditioning and the heating of rooms and sanitary water, in residential and tertiary sectors, represent approximately the 20% of the total energy consumption.
The heat pump may represent a perfect solution for the heating and conditioning of the houses, as well as for the reduction of the energy consumption at home and in the offices.
The heat pump is an appliance able to transfer heat from a room with lower temperature to a second one with a higher temperature, working on the same basis of a common refrigerator.
Have you ever tried to put your hand behind a refrigerator? You will feel warm: this heat has just been subtracted from the inner of the refrigerator, to make it cold. Your refrigerator, indeed, takes heat from his inner space to release it outside. The heat pump, instead, works in a diametrically opposite way, taking heat from the environment to release it in the house heating system.
The heat pump is built on a closed-circuit, covered by a special fluid called refrigerating, which, according to the surrounding conditions of temperature and pressure, assumes a liquid or steam form.
The external mean from which the heat is taken is called “cold source”. The main cold sources are:
- the air, external from the room that hosts the heat pump, or taken from the room where the pump has been placed;
- the water: taken from the layer, from rivers or lakes, if it is present near the rooms to be heated, and in small depth.
To know how efficient could be a heat pump, it is sufficient to calculate the ratio between supplied energy, that means the heat given to the place to warm, and the consumption of electric energy. This value, called performance coefficient “C.O.P.”, depends from the kind of heat pump and also from its operation conditions and normally shows amounts near 3: this means that for 1 kWh of used electric energy, the heat pump will give 3 kWh of heat to the place to warm. The lower is the temperature to which the heat is given and the higher is the temperature of the source from which it is taken, the higher will be the C.O.P. Under a temperature from -2°C to 2°C the heat pump de-activate itself, because its performances would significantly decrease.
The advantage of this pump derives from its ability to grant more energy (in the form of heat) than the electric one employed for its functioning, because it takes heat from the external environment. The application of this system to air-condition the residential and tertiary sectors rooms represents a valid alternative to the conventional systems, based on refrigerator and boiler. The same machine, as a matter of fact, is able, thanks to a single valve, to invert its functioning, giving heat in winter and cold in summer (Invertible heat pump). The heat pump, moreover, is a really versatile system that allows a lot of applications in the tertiary and industrial sectors, like swimming pool air-conditioning, dehydration and all low temperature technological processes in food farming, etc.
We should not forget that the heat pump could be also applied in previously existing buildings, not only in the new ones: in this case the integration of the heat pump to provide the winter and summer rooms air-conditioning will require a renovation of the whole thermal and electric system, with a consequent cost increase.
Geothermic heat pumps
Geothermal systems are able to exploit the physical capability of the soil to be a good thermal accumulator. Unless special phenomena, it takes just few meters of depth to preserve a constant temperature for the whole year (from 10° to 14 °C): every place on Earth shares this same feature, which is tightly linked to the capability of the soil to keep and store the solar radiation, in the form of clean and renewable energy. You know, a lot of animals survive thanks to this characteristic of the ground: creatures like the desert Fennec or the Badger, in effect, find a shelter and protection underground to resist to the adverse climatic conditions (high or low temperature).
The constancy of the soil temperature involves a double beneficial effect: during the winter period, the ground has temperatures warmer than the external air, while, during the summer time, the temperature is lower than the air ones. In winter, the heat pump will absorb heat from the soil, rather than from the external colder air, while in summer the land could be used to disperse the heat.
A geothermal heat pump is an excellent example of energy obtained in an efficient way: to produce the 100% of heating energy, it only takes the 25% of consumed energy, while the remaining 75% comes from the solar energy, stored in the soil.
The energy certification
Class A buildings
From the 1st January, 2007, in Italy it is compulsory the energy certification. The enactment of the Directive 2002/91/CE, in fact, has been realized with the D. Lgs. n. 192 on 19th August 2005, recently revised and integrated from D. Lgs. n. 311, published the 29th December 2006.
The energy certification for a building is required to value its energy efficiency, as well as to foresee its administration costs about the energy consumption. The energy certification immediately underlines the total amount of the energy requirement for every building, thanks to two energy classifications: the first one concerns the class of thermal isolation of this house, the second one mainly concerns the quality of its plant design. Using a table divided in coloured boxes, from green (low energetic needs) to red (high needs), whoever could easily understand how much energy is utilized by a building. This is the same process used to classify the household appliances, on the basis of the energy efficiency.
Thermography is one of the most recent technologies allowing to make an accurate analysis of the single building, locating the critical points where it is necessary to intervene, to reduce the energy consumptions. Thermography is a useful instrument to make a correct energy certification of buildings.
Thermography is an approach that utilizes the physical principle, in accordance with each body with a temperature higher than absolute zero (-273,14°C) emits energy, in the form of infrared radiation. The instrument that converts the energy emitted from a body or a house in a digital signal is called thermo camera. This instrument detects a “vision of the energy” represented by an image, that is the thermal map of the house, where every colour represents a precise temperature. The thermography t research shows with precision the energy critical zones (with great thermal exchanges), for instance the coldest and dampest walls, the areas with larger heat dispersion, and so on.
Therefore, the energy certification is an important instrument to achieve the targets of improvement of the energy performances, of energy consumption and pollution reduction.
Reduce the pollution, too
Paintings and varnishes
Paints and water enamels, often described as ecological ones, are not.
They have to be preferred to the oil paintings or solvent varnishes, but however they contain about 15% of solvents and other harmful substances.
There are ecological paints, made with natural ingredients (vegetable and mineral ones), good for every quality of finish: from the tinting of external or inner walls to the enamel painting, till the treatment of wood and baked clay.
The casein is a compound of milk proteins, obtained with curdled milk. Casein, in the form of powder, is mixed together with the marble powder and borax, creating a perfect binder. Some ancient works created in this way are still exposed in churches and museums, proving the high quality of the casein painting.
To paint with spices and flowers
Spices like curry, turmeric, sandalwood and saffron, and some dyer flowers, conveniently grinded and pulverized, are perfect natural pigments. They offer us a lively and pulsing colour, but they are also able to stimulate the sensory perception continuing, for some time, to give their scents off.
Cork, wood or coconut fibres, expanded clay are perfect materials to avoid heat dispersion. And they are good acoustic insulators, too!
Recycled Pieces of funitures and building materials
The glass gravel made with 100% recycled glass is used to drain and thermal isolating the foundations and buried walls, while thermal and acoustic insulators made with polyester fibre derive from the recycle of PET bottles.
Ecological pieces of furniture are made with renewable materials, recyclable and diffused on the territory. Moreover, it is very important to have a short distance from the source of these materials and the working place, to limit the CO2 emissions during the transportation. The ecological pieces of furniture are easily recyclable at the end of their operative life, and they are made with a low environmental impact process.
With 67 plastic bottles we can produce the stuffing of a double eiderdown, it takes just four wooden pallets to build a desk, while with 11 milk boxes we can create a watering can.
These are just few concrete examples of recycle. The use, the recycle and the new use of some materials, like aluminium, glass, steel and cardboard allow the creation of complementary pieces of furniture, always more innovative and ecological. Recycled glass and aluminium are often used to create floors, while tables, chairs and armchairs could be manufactured using cardboard, wood, steel or recycled aluminium.
written by Benedetta Palazzo