Keys to choose windows that save up to 30% of energy in the house
December 21, 2017
Most of the time, when we think of comfort at home, we immediately associate that idea with a soft sofa, large comfortable beds, spacious rooms, a well-equipped kitchen, etc. But almost never comes to mind in that comfort an element that goes unnoticed, but that is essential to achieve the desired well-being at home: the windows.
Because windows consume 13% of the energy in single-family homes, that is, 13% of the heat of our home escapes through them. A percentage that can reach up to 23% in the case of housing blocks, according to OnVentanas. Precisely, the construction elements that separate the house from the outside are one of the weak points to achieve thermal comfort at home, and the windows are one of the weakest links, as they not only provide thermal insulation, but also acoustic (they protect from noise) and provide light, ventilation and security.
Therefore, it is essential that our windows have a series of features to fulfill that function for which they were designed. Now, with autumn knocking on the door, it is a good time for renovation and even renovation so that when winter arrives our house is well protected and we do not waste energy, as much as we raise the heating, if the windows are poorly insulated, it will not help. More than to empty your pocket.
The essentials that should not be missing in your window
First of all, we must be clear that the quality of the windows is directly proportional to the materials from which they are made. That is to say, the quality of manufacture of the joints, the material of the frame, the fittings, the glass or the whole of the blind will define the performance of the window. Although it must be borne in mind that the necessary characteristics of each window will depend on its location, since according to this, it will be necessary to bet more for one or the other.
For example, in the case of glass, which generally occupies between 60% and 65% of the total area of a window in Spain, it has a decisive influence on the comfort of our home. However, few know that according to the orientation of the window the glass should be of one type or another:
Practically exposed to solar radiation, only in the early hours of the morning. For this reason, there is not much sun through the windows, so it is recommended that the glass be large, that is, that the window has more prominence in the glass than the frame to let as much light as possible pass without excessive heat losses. For this it is also important that the glasses are low emissive, that is to say, that they have the capacity to reduce the heat losses by the reflection that they make of the energy radiated by the heating devices. In this way, these crystals act as a shelter that maintains the heat of the heating in the rooms thanks to its 'rebound effect'. In addition, in this case, to the north, the glass does not need solar protection.
South orientation: in this case, and contrary to what you may think, solar radiation is higher in winter than in summer, therefore, they are recommended crystals also with the ability to maintain heat (low emissivity) and a medium solar factor to protect the house in summer and avoid overheating and to collect part of the free energy of the sun in winter. To reinforce this sun protection it is recommended to install cantilevers, setbacks, awnings, blinds or curtains.
Orientation east and west: in this case, the solar radiation is direct, so it is convenient to equate the windows of the exterior with the adequate solar protection that is able to reduce the heating of the interior spaces and glare. Therefore, the best option is to use glass also with the ability to reflect energy and a high solar factor, that is, not to let the sun's energy pass through.
The exception will come in the windows where there is a solar protection independent of the window, such as awnings. In these cases the glass may have a low sun protection, so that in winter it lets the sun's energy pass.
There is also the option of double glazing -also called glass with a camera-, which are formed by two or more sheets of simple crystals separated from each other by one or more spacers. In fact, in Spain most windows have double glazing. If these glasses are also low emissive and reduce heat losses can generate energy savings of between 2% and 13%.
But when it comes to preventing the heat from going away, not only glass intervenes; The work of the carpentry frame and its installation is also important. It must be clear that all types of carpentry require cleaning and lubrication of fittings and, in the case of woodwork, should be taken into account especially the protection of the finish (paints or varnishes) and biocidal treatment (which prevents the external agents spoil the window).
The frames are usually made of wood, metal or PVC but, generally, slits are produced that allow air to pass through. This property is known as permeability and, as a consequence of it, air filtrations are generated that produce heat and cold losses in winter or summer, respectively. However, wood and PVC are insulating materials, so in carpentry made with these materials there are no thermal bridges if they are installed correctly and, as a result, no air is filtered. On the other hand, metals, due to their high conductivity, are not insulating materials, so, to improve their performance, plastic pieces and air chambers must be interposed, which are called carpentry with thermal bridge breakage.
Finally, for the saving of energy and for protection against noise, the fixation of the frames of the carpentry and that of the shutter boxes must be done in such a way as to ensure a watertightness to the permeability of the air. With all these measures, energy savings can range between 5% and 30%.
And as a final shot...
In the end, there are other allies that reinforce this protection against solar radiation and energy leaks. It is the mobile elements, well known by all, because we speak of awnings, blinds and adjustable slats. As for the first, it is advisable to carry out a regular maintenance of the whole system, with special emphasis on the tarpaulin, since it is the element that gives shade. In summer, it is advisable to unfold the awning before direct light enters the house, while when it is windy it is necessary to collect it so that it does not come off. If it rains, you have to wait for it to dry to roll it up so as not to damage the canvas.
The blinds should be closed in summer during sunny hours and up at night, while opening the windows of opposite facades to be able to cause cross ventilation and to renew the air of all rooms of the house getting the quality of proper air. It is important to take care of the winding tape or crank, avoiding its sudden action or letting them fall suddenly. In addition, during prolonged absences (such as vacations) we must not close them completely, since exposure to the sun produces a high concentration of heat that can damage the slats.
Finally, we must not forget that the window must also protect us from any type of intrusion from outside, especially in vulnerable areas, such as holes in the lower floors, attics, etc. For this it is advisable to place 'defense' systems as folding, extensible, rolling and even fixed closures.
With all these recommendations, the reform of the windows will be a success that will be noticed in the bill of light / gas this winter.
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