How Double-hung Windows provide Natural Ventilation

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You must have always heard that the most effective method to increase ventilation in your house, especially in a small to medium sized house, is to use double hung windows. In this article, we will give you insights on how these double hung windows provide this kind of ventilation.

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The phenomenon of passive movement of air through a building from differences in upward pressure due to thermal buoyancy makes the foundation of stack ventilation. When the air inside a building is warmer than the outside air, the warmer, the less dense air will rise. Stack ventilation takes advantage of this effect by constructing openings in the building envelope high at a substantial height, allowing the warm air to escape. The negative pressure at the top of the building draws in colder, denser outside air through openings low in the building. Naturally, this effect is relatively weak, but it can be concentrated through the use of a stack. Longer stacks will typically increase airflow.

Dedicated stack air exchange systems will typically feature a series of hot air vents at roof level and cold air inlets along with the lower parts of the exterior walls. The hot air outlet vents should ideally be located as high as possible; the stack effect becomes more pronounced when the distance between inlet and outlet points increases. Larger, multi-floor buildings usually have a central hot air duct which leads to the roof of the structure with warm air vents at ceiling level on each floor. The cool air inlets are then usually fed by air which is drawn up a separate cool air duct by fans. This duct will have a set of intake vents at ground level.

A double-hung window features two overlapping sashes. It can be opened at both ends- top and bottom. An average sized double-hung window has openings that are at far apart from each other so to as create a perfect airflow. These windows are based on the concept of stack ventilation. When the warm air inside your house rises, the top half of the window vents warm air from the room. The pressure difference then created causes the lower half of the window to pull the fresh air in, resulting in proper ventilation.

Advantages of using a double hung window for natural ventilation

As mentioned earlier, double hung replacement windows are ideal for small and medium-sized rooms and areas that have only enough wall space to fit a small window.

  1. Keeps pollutants away

Allowing ventilation for a minimum of fifteen minutes a day can bring about a massive change in the level of contaminants in your house. Indoor air pollutants include emissions from household items such as paint, plastics, and aerosol products. Similarly, cooking and smoking can also cause a rise in the level of indoor pollutants.

  1. Flexibility in vent placement

Due to the relatively small size of such windows, double hung windows offer great flexibility to you. They can be placed on a small wall in the room, basement, and attic and also in the stairwell of your house.

  1. Regulates indoor humidity level effectively

Double hung windows have time and again proven to be the most effective ways to ventilate your room or house naturally. It helps regulate indoor humidity as well. Condensation on the window is indicative of moisture and can be removed with regular ventilation. Natural ventilation prevents the growth of mold and mildew which if left untreated can cause allergies and other respiratory ailments. Like other styles of windows, a double hung window provides ample ventilation, with just one window.

  1. Non-reliance on wind patterns

The operation of double hung windows does not really depend on the wind patterns unlike many other forms of ventilation. It works on the principle of Bernoulli’s principle, wherein a pressure difference is created which facilitates ventilation.

  1. Stable flow

Double hung windows provide constant and steady natural ventilation. You need not even open the window entirely for the whole day, fifteen to twenty minutes each day provides enough ventilation for the day.

Numerous are the benefits of having a double hung window installed at your place. You must hire an expert now and you yourself will be able to experience the difference.