UNDERSTANDING THE STACK EFFECT
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THE STACK EFFECT The Stack effect also called the chimney effect, is the movement of air into and out of buildings and through areas such as chimneys. This effect results in buoyancy that occurs due to a difference in indoor-tooutdoor air density. Air density depends on thermal and structural variations. For this reason, the greater the buoyancy force, the greater the stack effect.
Under the stack effect, warm air inside a building rises on cold days. This phenomenon pressurizes the top of the house or building and pushes hot air out while cold air is sucked to the bottom. In summer days, the stack effect works in reverse. When buildings and houses are not adequately sealed, the stack effect causes air leakage. For this reason, warm indoor air escapes at the top through any opening during the winter season.
COLD DAYS During winter, the stack effect can be a problem because people on the upper floors are overheated, and when they open the windows, they relieve pressure at the top and draw cold air in at the bottom, making people on lower floors feel uncomfortable because of low temperatures. Hence, the stack effect is more problematic within multifamily buildings that have poor insulation.
CONDENSATION When a building experiences a large flow of air between the interior and exterior, moisture tends to condense on cold surfaces. The most typical symptoms can be noticeable in brick buildings, where the action of the stack effect causes staining and efflorescence.
THE DISADVANTAGES OF NATURAL VENTILATION Natural ventilation is suitable for some buildings located in mild or moderate climates. In this sense, natural ventilation can be an inexpensive option compared to the use of mechanical and electric systems. However, natural ventilation usually leads to inadequate control over ventilation and excessive heat loss. In the same way, natural ventilation is not suitable for polluted and noisy areas.
When the stack effect causes energy loss, unconditioned air requires more energy to heat or cool a space. Therefore, the best solution is to choose a durable and professional method to insulate your crawl space.
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