Windows and Doors are elements of fundamental importance in DomusGaia projects.
Positioning of doors and windows is studied in the first phase of the project using bio-climatic architecture methods that permit to gain the maximum solar gain during the winter , and, on the other hand, architectural projections and shadings are provided to avoid overheating inside during summertime.
Windows and Door have triple Low-E insulating glass units and they an be made of wood, pvc, wood/aluminium, pvc/aluminium or thermal cut aluminiun if the windows are very big.
Transmittance (Uw value) is the thermal performance classification given to a window. It measures the rate of heat transfer through its surface. The higher the Uw rate of the window, the higher the heat passing through it. So a good window will have low Uw values.
WINDOW AND DOOR COMPONENTS
The performance of a window/door system in terms of thermal insulation depends on its components, which means glass transmittance (Ug), frame transmittance (Uf) and the transmission of heat through the contact point between glass and frame (psi). So the better the thermal quality of its components, glass, frame, edgings, the easier it will be to achieve a good final result. The same goes for the edging which separates glasses, called “warm edge” , thanks to the fact that it is made of high mechanical resistance materials which do not conduct and loose heat. This permits to limit dispersal of energy to 10% compared to a window with a traditional edging and it avoids the unpleasant phenomenon of condensation forming between glass panes and over the edges which is typical of edge trims.
With Mediterranean Climates, however, it is important not only to avoid heat to escape from inside to outside during the cold months, but also to avoid heat to penetrate inside during the warmest months. The parameter that helps you assess the quality of an insulating glass is the “solar factor” (g value), which is the ratio between the solar energy transmittance on the glass and heat transfer through the pane. Typical values of solar factor are 62% for double glazing and 52% for triple glazing, which means that these glass let respectively a percentage of 62 and 52 of the solar energy that hits them, come in.
This aspect is of great help at the point where, for various reasons, it seems impossible to provide adeguate shade over building openings; and you must keep in mind that national regulations indicate that shadings are the principal and most effective strategy used to prevent summer overheating, and the same thing is prescribed by bioclimatic architecture principles. So much that the norms state that without proper shadings, glass slar factor must be less than 50%, A factor which is usually underestimated when evaluating the quality of a window or door, is the position of the window/door based on its flush to wall, whether outside, inside or “mazzetta” and this could affect up to 100% the thermal transmittance of the windows and doors installed.
QUALITY OF INSTALLATION
Also important is the quality of installation in the building phase, which has be realized by trained personnel, choosing materials suitable to assure airtight windows and doors. Draughts are not only uncomfortable to whom are exposed to them, but they also cause heat dispersion in relation with the entire wall. In addition, the uncontrolled passage of air and vapor through small gaps may cause serious damage to the back structures (plastering , coating, shoulders) in just a few years, nullifying expenses and efforts incurred to have a warmer and more efficient home.