Increasing the energy efficiency of buildings can reduce heating and electricity bills by about 40%. However, to avoid annoying condensation formation on windows during winter, such a change needs to be carefully planned and designed.
Two key factors contribute to condensation formation in cold weather: improper windows and high humidity indoors. Condensation occurs when moisture from the air meets a cold surface. If the interior is warm and the window is cold, the moisture from the warm room will naturally "stick" to the cold glass. In other words, preventing condensation comes down to preventing the meeting of moisture and a cold surface.
The critical choice of the "right" window plays a significant role in avoiding condensation. The insulated glass unit (IGU) is crucial. A standard IGU with two layers of clear glass cannot prevent the transfer of cold between surfaces in low-temperature weather conditions. The situation becomes more complicated if the window, for example, faces north and receives minimal sunlight exposure during most of the day or is located on a facade frequently exposed to cold winds.
Three important steps should be considered when determining the IGU:
The glass should be low-emissivity (low-e).
The IGU should be constructed with a warm-edge spacer instead of an aluminum spacer.
It is desirable for the IGU to be filled with an inert gas like argon.
The window frame also plays a secondary but crucial role. If the window is exposed to harsh winter conditions, it is preferable for the frame to have excellent insulation properties. Wooden and PVC windows provide such insulation naturally due to the properties of the materials they are made from (wood or polyvinyl chloride).
Significant insulation can also be achieved with aluminum profiles, but the balance between the achieved effect and the cost complicates this solution. It would be justified only when architectural features and building design require a specific appearance that cannot be achieved with vinyl or wooden window systems.
There is no universal formula for the "right" window. Determining its parameters correctly is possible on-site by a specialist who takes into account the size, energy efficiency of the building, construction materials, heating and ventilation systems in the building, facade orientation, wind load, and various other factors.
Eliminating humidity from the interior is also essential.
Reducing sources of moisture in the interior is the second important step in preventing condensation. It is crucial because with a properly selected high-insulating window, the moisture in the space will seek another cold surface to condense on, which is likely to be a cold wall, for example, making the moisture a precondition for mold development and even more dangerous.
What can be done?
-Limit air exchange with rooms with high humidity such as the bathroom, kitchen, and laundry room. These traditionally humid spaces should be equipped with adequate ventilation systems (fans, exhaust hoods) to remove the steam outside the interior. However, it is also good to keep their doors closed, as humid air tends to escape the boundaries of the rooms and infiltrate the rest of the interior.
-Dry laundry outdoors.
-Limit greenery indoors. While vegetation is generally desired in homes and offices, watering them inevitably leads to water evaporation.
-Ensure proper ventilation: brief airing of the house in the morning and evening can prevent the accumulation of excessive moisture in the air. Ventilation is particularly important when using gas (propane) heaters, as the burning process releases a significant amount of fine vapor into the air. Additionally, spaces such as the bathroom, kitchen, and laundry room should be ventilated more intensively.
-Position heating devices: It is not a coincidence that radiators in panel buildings are located precisely under the windows. This solution by engineers is related to the so-called convection or "chimney effect" - a process in which heated air rises. Placing heating devices near windows heats the coldest layer of air located next to the inner "face" of the window. This provokes significant air circulation that prevents condensation of moisture from the air on the windows.
-Avoid thick curtains and placing furniture in front of windows, which can cause stagnant air around the windows.
-In case of excessive humidity concentration, the use of a dehumidifier may be necessary. When the above principles are followed, this should not be necessary, but there are situations where moisture comes from other sources, such as in a newly constructed building where construction materials may still be drying. This is a process that takes about a year and a half, and even when the above principles are followed, there may be excessive moisture during that period.
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