Windows, ventilation, moistness and frost
Windows are the main waster of heat, on the one hand because of the good conductivity of glass, on the other hand because of the leak around the frame. If you have old windows somewhere, just put the hand around it, particularly if there is wind.
The conductivity of a pane of 4 mm of thickness is 1/0,004=250. That is to say that 1 m2 of window wastes as much heat as 125 m2 of a breeze blocks wall, without any insulation. This windows protects only from the draughts and from the wind. That is why, in northern countries, has been invented the double-glazing window.
All this time before inventing it. It is true that coal was not expensive and the mine were the power of the nation.
The idea behind the double-glazing window, it is to enclose air inside it, because we said that the best insulating after vacuum is calm and dry air. The double window, which is expensive and bulky, has been replace by the double-glazing window which enclose a dry gas. Why is there no vacuum, the insulation power is much better ? Because, under the effect of atmospheric pressure, the two windows would implode one against each other (The same problem goes for cathodic screens). It is the space between both window that determines the quality of insulation of a double-glazed window.
For instance, with e=8mm, this leads to a conductivity g=λair/e=0,025/0,008=8,33, if e=16 this gives g=1,56.
Here is the miracle : we got from 250 to 1.56. As a piece of evidence, in the past, on single-glazed windows, there often was condensation. Now, with double-glazed window, you do not see condensation anymore, or very scarcely. Why ? It is the principle of the cold side : when the hot and humid air of the soup which is boiling comes close to a cold surface, it cools and the steam that it contains condense into fine drop, because the temperature of the air is under its dew point.
If the air (or nitrogen) of the double-glazed window is replaed by argon, rare gas that exist in the atmosphere, which has the advantage of having a λ smaller, but a price of useing higher, this leads to g=0,020/0,016=1,25.
But warning, a breeze block wall of 20cm covered with 10cm of polystyren has a conductivity of 0,33, and 1 m2 of this excellent double-glazed window has the same deperdition as 4 m2 of insulated wall. That is to say that if you have large picture window that cover the 3/4 of your façade, then no need to insulate the wall !!!
It is pleansant to have large picture windows with a panoramic view on the landscape, this cost some calories in winter. But in summer, the sun penetrates and heat the tiled floor or the marble, the terrace reflects the infrared rays toward the ceiling and you living-room becomes an oven. It only remains for you to look for the shadow of big trees. If you are lucky enough to be close from a river, you will feel its coolness, because the water represents a cool face and good conductorof heat which absorbs your radiated energie., and furthermore, because of the evaporation, the air is more humid and hence better conductor and absorbs more easily you heat, and lastly the evaporation absorbs the energy and thus creates coolness : that is why one sweat when being too much hot.
At night, the heat accumulated spread in the house, and it is hot everywhere
If the large windows are suppressed, when it is cloudy, it is dark in every room. There is no ideal solution. Blinds in summer and glass wall in winter, no terrace on the south side, especially in hot areas.
The second cause of loss of the windows are the leak of air between the fix frame and the mobile leaves, leak which depends also on the wind pressure. Modern windows are very studied, with gasket, and absorption grooves and imprisonment of air to insulate according to the navy principles. The strenght of the water or of the wind is smashed, a volume is left to make the pressure decrease and then a joint which does not undergo any movements of the fluid look after watertightness.
Windows had also to ensure the renewal of the air in the rooms for breathing, extracting humidité from the kitchen and the breathing, the chink under the doors giving to outside brought the air for the stove or the chimney.
Now that the doors and windows are perfectly airtight, you are todl to add chinks in the chassis, or in the panes, in order to ensure this renewal of the air, which is cold air because it comes directly from outside. Then on one hand, you are sold airtights windows in order to make energy savings, and on the other and, they are made non-airtight by adding big chinks for the ventilation.
That's contradictory !!
The solution is to replace these chinks by a mechnical ventilation double-flux. Because the cold air that enters the house replace somehow hot air that goes out.
This installation consist of aspirate hot air from the technical room, the kitchen, the toilets and the bathroom and throw it outside after it be passed through a heat interchange in which new cold air from outside goes in opposite direction. This cold air, heated in the interchange, is then insufflated into the comfort rooms, such as the living room and the bedrooms.
60% of the air extracted is thus recuperated, which means that, because the extracted air is at about 25°C, if it is 0°C outside, the air which is insufflated is at 15°C, instead of being at 0°C when it comes in through the chinks of the windows.
This permanent renvewal, regular, of the air, allow also, by extracting hot air which is humid because it contains all the mist produced in the house, to maintain the house in a hygrometric state close to the one of the outer air and thus avoid the deposit of moistness in the house, particularly at the level of the thermal bridges.
Indeed at the level of the thermal bridges, the cold wall is in contact with the hot and humid air of the house. That air cooling, the mist which it contains set itself down under the form of tiny drops like dew or fog. The wall becoming humid, it becomes more heat conductor, and the thermal bridge effect is thus more accentuated, which accentuates the condensation and henceforth. Hence the tapestry which comes unstuck, the humidity spots, and even the water oozes at the bottom of the walls.
The house becoming more humid becomes more difficult to heat. Because humid air is more heat-conductore, it takes you more heat, and hence you feels colder.
And warning : when freeze falls on the walls impregnated with water, the water changes into ice and, the same way as the bottles which breaks under the volume increment of the ice, the wall fissures. It is the same phenomenon than the rocks which fall on the roads in mountain in winter.
With outside insulation, the wall are well wrapped, in the warmth, no thermal bridges, no condensation, no heat loss increase, no freeze, no fissure.
About the shutters : if they are relatively airtight, the create a volume of still air which ensures a complementary insulation between the windows and outside, thus reducing the loss by convection of the windows, especially when there is wind. One celsius degree can be won.