Natural ventilation: Uncontrolled air movement into a home through cracks, small holes, and vents, such as windows and doors. Not recommended for tightly sealed homes.
Whole-house ventilation: Controlled air movement using one or more fans and duct systems.
Spot ventilation: Controlled air movement using localized exhaust fans to quickly remove pollutants and moisture at their source. Typically used in conjunction with one of the other strategies.
Natural ventilation can be a key element of cooling strategies in many climates. Mechanical ventilation can also be part of cooling strategies (that's the case of the ceiling fans), but it involves also other goals: remove stale and polluted air, distribute fresh air, etc.
Natural ventilation
Natural ventilation is the process of supplying and removing air by means of purpose-provided aperture (such as openable windows, ventilators and shafts) and the natural forces of wind and temperature-difference pressures.
Natural ventilation may be divided into two categories:
Controlled natural ventilation is intentional displacement of air through specified openings such as windows, doors, and ventilations by using naturalforces (usually by pressures from wind and/or indoor-outdoor temperature differences). It is usually controlled to some extent by the occupant.
Infiltration is the uncontrolled random flow of air through unintentional openings driven by wind, temperature-difference pressures and/or appliance-induced pressures across the building envelope. In contrast to controlled natural ventilation, infiltration cannot be so controlled and is less desirable than other ventilation strategies, but it is a main source of ventilation in envelope-dominated buildings
The simplest version of natural ventilation is opening windows and doors, to benefit from breezes. But natural ventilation - cross and stack ventilation - can be part of a more elaborate approach for cooling homes, involving features like home design, landscape, placement and size of openings, etc.
Cross ventilation
When windows are open in opposite sides of the house to cool the indoor temperatures, it is cross ventilation.
Stack Ventilation: the Chimney Effect
Natural stack ventilation (also called convective ventilation) uses a physics natural law: the chimney effect or air buoyancy. In natural stack ventilation, the warmer indoor air rises up from lower living areas and escapes through the upper openings of the building, causing cold air infiltration through windows or other lower openings.
Simple roof level ventilators, can be an effective way of achieving the objective of ventilation such as
Low maintenance
Easy control interface
Reduces the ‘carbon footprint’
Saves money on energy consumption
Reduces forms of smells, musty odors, conditions fostering mold, excess humidity, tobacco smoke, cooking odors and out-gassing from chemicals, carpets, and construction materials
Climates and natural ventilation
Natural ventilation loses much of its power in cold climates or even in hot-humid climates. Unlike mechanical air-conditioning, natural ventilation doesn’t reduce the humidity of incoming air, making the cooling process rather ineffective during periods of high humidity (in hot-humid conditions). Higher humidity conditions require greater air-speeds and greater ventilation to provide comfort. And the breezes and shaded spots associated with natural ventilation may not provide those pre-conditions
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