Window frame replacement

Window frame replacement: The necessity, modern solutions

The need for energy conservation is becoming increasingly urgent these days, as a series of significant changes have occurred in the way we perceive the issue of construction and the built environment. The older perception that man, with the help of technology, can be independent of nature and the climatic conditions it imposes, can no longer be accepted, as it has proven to be environmentally harmful.

In recent years, a series of technological developments in the field of heating and cooling devices have made it possible to artificially regulate within buildings the desired values for a series of parameters such as indoor temperature, humidity, ventilation, lighting and air quality. Thus, man felt omnipotent, acquiring the illusion that he was capable of inhabiting the most inhospitable parts of the planet, applying the same building model, whether in low or high latitudes, without caring about the consequences that this attitude would have on the environment.

Today, reasons such as the increase in fuel consumption internationally, resulting in the increase in the prices of primary and secondary energy spent on heating and cooling buildings, and the continuous environmental degradation with climate changes 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 humanity was based in the previous period. In fact, the adoption of measures by states with stricter legislation, in order to optimize the energy performance of building projects, was inevitable.

The direction of evolution must now be increasingly focused on the formation of a better human-made environment from all aspects. One of the most important areas of action for scientists is that of the built environment, where new techniques, new materials, systems and building philosophies promise encouraging results in the direction of energy saving initially, but also subsequently, in the production of the energy required for each building in a more economical and environmentally friendly way.

As is known, the greatest heat losses occur through the openings of buildings. Therefore, the factor that significantly affects the energy performance of a building is the type of frames that are to be selected to cover its openings. In all cases, thermally insulating aluminum frames, opening or sliding, should be installed, which will be combined with thermally insulating glass panels with low thermal radiation emission (Low-e). The benefits of installing thermally insulating aluminum systems are the energy savings achieved for heating and cooling and the provision of a healthier environment.

Energy Efficiency of Buildings Regulation (ENEB)

Newly constructed buildings, as well as existing ones, will be subject to inspection by specialized energy inspectors in accordance with the provisions of the Regulation on the Energy Efficiency of Buildings (KENAK) in order to certify their energy efficiency. Based on the latter, they will be classified into individual energy categories and the corresponding energy identity card will be completed, which will constitute an integral element of the building permit and will become necessary in all legal transactions that will be drawn up for the property.

KENAK aims to:

– Saving energy for heating, cooling, lighting, and ventilation of buildings by limiting energy requirements.

– Ensuring hygienic and comfortable living conditions for building users by maintaining appropriate levels of thermal and visual comfort.

– The implementation of the principles of bioclimatic design accompanied by the increase in the use of those devices that contribute to the exploitation of renewable energy sources (photovoltaics, wind turbines, passive heating-cooling systems, etc.).

The building's heat losses

Regarding the mechanism of heat loss from buildings, it can be noted that they lose heat in three main ways:

  1. by conduction, through walls, roofs, floors, glass openings.
  2. by transfer with the movement of air, through open windows or through the joints of the frames.
  3. by radiation, from the building shell, when external temperatures are lower.

Energy saving by using aluminum thermal insulation systems

Ensuring thermal comfort conditions inside buildings, with the minimum possible energy consumption, requires limiting heat losses from the surface of the frames to the external environment during the winter period and reducing unwanted heat gains during the summer. The flow of heat depends on the temperature difference between the internal and external environment, as well as on the thermal resistance of the materials that make up the frame.

Specifically in aluminum frames, the most common method to limit the flow of thermal energy is to add thermal insulation, i.e. materials with high thermal resistance between the aluminum profiles. The thermal losses of a frame come from its transparent and opaque elements and depend on the average thermal transmittance coefficient of its total surface (glass pane and aluminum profile).

The purpose of thermal insulation in aluminum systems is also to avoid thermal bridges, that is, the creation of water vapor and humidity inside the frames, which increase heat losses and create different thermal stresses in the individual materials that make up the structure.

Overall, replacing a building's old frames with thermally insulated aluminum frames results in:

  • Increasing thermal comfort in indoor spaces.
  • Reducing the possibility of water vapor formation on the surface of aluminum profiles.
  • The significant reduction in operating costs for heating and cooling due to energy savings, a reduction which, taking into account specific factors, can even reach a percentage of 30 – 40%.
  • Improving the thermal insulation performance of buildings, by maintaining the desired solar gains for a longer period of time within the building.
  • The protection of the environment through the reduced requirement for energy use, thereby avoiding the release of greenhouse gases into the atmosphere that contribute to the intensification of the climate change phenomenon. Also, the choice of aluminum systems is the most environmentally appropriate solution for another reason, as it is a recyclable material.
  • In the energy upgrade of buildings, and therefore in the increase in their commercial value, according to the new data set by KENAK.
A key issue in the field of achieving better thermal insulation in the building as a whole is the position of the frame in the masonry. A thermally broken frame must be placed in the same line as the thermal insulation line of the masonry, in order to avoid the creation 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 curves of the frame - masonry are on the same line. In the case where there is no insulated wall, the position of the frame does not play a significant role in thermal insulation.

Finally, an important environmental issue that arises is that of the management of old window frames. Old window frames are treated as "waste" and as such, there must be a specific policy for their collection and disposal. The categorization of old window frames according to their construction material (iron, wood or aluminum) and their possible recycling is an issue that must concern solid waste management bodies.

“Aluminium Magazine”