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Frames replacement: The necessity, modern solutions

The need for energy savings is becoming more urgent nowadays, as a number of major changes have taken place at the way in which we see constructions and the built environment. The older notion that man with the help of technology can be independent of nature and the climate conditions it imposes, can no longer be acceptable, as it has been shown to be environmentally damaging.

Over the last years a series of technological developments in the fields of heating and cooling devices, gave the possibility of adjusting within the buildings, with technical ways, of the desired values ​​in a number of parameters, like the temperature of the internal rooms, humidity, ventilation, illumination and air quality. So man felt omnipotent, acquiring the illusion that he is capable of inhabiting the most inhospitable parts of the planet, applying the same construction model, whether they are small or large latitudes, disregarding the consequences of this attitude to the environment.
 
Today, reasons like the increasing fuel consumption internationally resulting in an increase in primary and secondary energy prices, which is spent on heating and cooling buildings and ongoing environmental degradation with climate change caused by the release of greenhouse gases into the atmosphere during the combustion of fossil fuels, indicate the wrong path on which the development of the economy and man was based in the previous period. As a result the need of the states to take more stringent legislation, in order to optimize the energy behavior of building constructions, was inevitable.
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The orientation of evolution must now be more and more focused on shaping a better anthropogenic environment in all respects. One of the most important areas of action for scientists is that of the built environment, where new techniques, new materials, systems and construction philosophies promise encouraging results in the direction of saving energy initially, but also afterwards, in producing the energy required for each building in a more economical and environmentally friendly way.
 

As is well known, the greatest heat losses are caused by the openings of buildings. Therefore the factor that significantly affects the energy behavior of a building is also the type of frames to be selected in order to cover its openings. In every case, thermal-brake aluminium systems must be installed, opening or sliding systems, which will be combined with thermal insulation Low-E glazing. The benefits of installing thermal-brake aluminium systems, is saving energy that is used for heating and cooling and also providing a healthier environment.
Energy Efficiency Regulation of Buildings (KENAK)
 
Newly built buildings, as well as existing ones, will be subject to scrutiny by specialized energy inspectors in accordance with the provisions of the Rules of Procedure for the Energy Efficiency of the buildings (KENAK) in order to certify their energy efficiency. According to the latter they will fall into individual energy categories and the corresponding Energy Identity Card will be completed, which will form an integral part of the building permit and it will be necessary in all dealings drawn up for the property.
 
 
The KENAK aims to:
 
  • Saving energy for heating, cooling, lighting, ventilation of buildings, by limiting energy requirements
  • In ensuring hygienic conditions and comfortable living for the users of the buildings maintaining the appropriate levels of thermal and optical comfort
  • In applying the principles of bioclimatic design accompanied by an increase in the use of those provisions which contribute to the exploitation of renewable energy sources (photovoltaics, wind turbines, passive heating-cooling systems)
 
The thermal losses of the building
 
About the mechanism of heat loss from buildings it can be noted that they lose heat in three main ways:
 
  1. conductive, through walls, roofs - roofs, floors, glass openings
  2. by transport with the movement of air, through the open windows or from the joints of the frames
  3. irradiated from the shell of the building when the outside temperatures are lower
 
Saving energy with the use of thermal-brake aluminium systems
 
The assurance of thermal comfort conditions inside the buildings, consuming as little energy as possible, presupposes the limitation of thermal loss from the surface of the windows to the outside environment during the winter season, and reducing unwanted thermal gains during the summer season. The heat flow depends on the temperature difference between the indoor and outdoor environment, as well as the thermal resistance of the materials that synthesize the frames.
 
 Specifically in aluminum frames, the most common method to limit the flow of thermal energy is the addition of thermal insulation that is, materials with high thermal resistance between aluminium profiles.
 
The thermal losses of a frame come from its transparent and opaque elements and depend on the average heat permeability coefficient of its total surface area (glazing and aluminium profile). The purpose of thermal-brake in aluminium systems is additionally the avoidance of thermal bridges, that is, the creation of vapor and moisture in the internal surface of the aluminium frames, that increases the thermal loses and creates different thermal stresses in the individual materials that compose the construction.
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Overall, the replacement of the old frames of a building with thermal-brake aluminum frames results:

 

  • Increasing thermal comfort indoors.
  • Reducing the possibility of water vapor formation on the surface of the aluminium profiles.
  • Significant reduction in operating costs for heating and cooling thanks to energy savings, reduction which, taking into account specific factors, can even reach a percentage of 30-40%.

 

  • Improving the thermal insulation behavior of buildings, by maintaining the desired solar gains for a longer period of time inside the building.
  • Protecting the environment through the reduced demand for energy thus avoiding the emission of greenhouse gases into the atmosphere, that contribute to exacerbating the phenomenon of climate change. Furthermore the choice of aluminium systems is the most appropriate environmental solution for one more reason, as it is a recyclable material.
  • The energy upgrading of buildings, thus increasing their commercial value according to the new data set by KENAK.

 

Key issue in achieving better thermal insulation in the building generally, is the position of the frame in the masonry. A thermal-brake aluminium system must be installed in the same straight line as the thermal insulation line of the masonry, to avoid the formation of thermal bridges but also to have a substantial effect on the thermal break of the frame. Better thermal insulation is achieved overall as the isothermal aluminium frame-masonry curves are in the same straight line. In case there is no insulated wall, the position of the aluminium frame does not play an essential role in insulation.

 

Finally, an important environmental issue arises is also the management of the old frames. Old frames are treated as 'waste' and as such it needs to have a specific collection and disposal policy. The categorization of old frames according to their construction material (iron, wood or aluminium) and their possible recycling is an issue that has to concern solid waste management bodies.