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Infiltration is the unintentional or accidential introduction of outside air into a building, typically through cracks in the building envelope and through use of doors for passage. [1]. Infiltration is sometimes called air leakage. The leakage of room air out of a building, intentionally or not, is called exfiltration. Infiltration is caused by wind, and by air buoyancy forces known commonly as the stack effect. Stack effect is the ventilation in buildings and chimneys that results from thermal differences between indoor and outside temperature. ...
Infiltration measures
The infiltration rate is the volumetric flow rate of outside air into a building, typically in cubic feet per minute (CFMs) or liters per second (LPSs). The air exchange rate, (I), is the number of interior volume air changes that occur per hour, and has units of 1/h. The air exchange rate is also known as air changes per hour (ACHs).
Infiltration as ventilation air In many smaller buildings, 'forced' or 'mechanical' ventilation is not used to introduce ventilation air. Instead, natural ventilation, via operable windows and other openings, exhaust fans, and infiltration are used to provide ventilation air. Typically, at least one-third air change per hour is considered the minimum. Recently, ASHRAE Standard 62.2 has been adopted (2004); it clarifies ventilation air requirements for low-rise residences. The Standard specifies when, for example, forced ventilation is required in houses. Return inlet (left)Supply outlet (right). ...
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) is an international voluntary organization for people involved in heating, ventilation, air conditioning, or refrigeration (HVAC&R). ...
Controlling infiltration Because infiltration is uncontrolled, and admits unconditioned air, it is generally considered undesirable except for the ventilation air purpose. Typically, infiltration is minimized to reduce dust, to increase thermal comfort, and to decrease energy consumption. For all buildings, infiltration can be reduced via sealing cracks in a building's envelope, and for new construction or major renovations, by installing continuous air retarders. In buildings where forced ventilation is provided, the HVAC designers typically choose to slightly pressurize the buildings, by admiting more outside air than exhausting, so that infiltration is drammatically reduced. A vapor barrier is a material that is impermeable to vapor. ...
Energy savings In typical modern U.S. residences, about one-third of the HVAC energy consumption is due to infiltration. Another third is to ground-contact, and the remainder is to heat losses and gains through windows, walls, and other thermal loads. As such, reducing infiltration can yield significant energy savings, with rapid payback. In cold climates, with a 15 MPH wind, residences often have air exchange rates of 1.0 to 1.5 ACHs, far in excess of the ventilation air needs and are thus called loose construction. While it is possible to build a house too tightly, e.g., 0.25 ACH, it is very easy to reduce infiltration rates to less than 1.0 ACH. Smoke candles and blower-door tests can help identify less-than-obvious leaks.
See also A vapor barrier is a material that is impermeable to vapor. ...
Return inlet (left)Supply outlet (right). ...
Indoor Air Quality (IAQ) deals with the health and comfort of the air inside buildings. ...
Example of good and bad ventilation Sick building syndrome (SBS) is a combination of complaints and symptoms (a syndrome) associated with an individuals place of work (typically, but not always, an office building), though there have also been instances of SBS in residential buildings. ...
HVAC (pronounced either H-V-A-C or, occasionally, H-VAK) is an initialism/acronym that stands for heating, ventilating and air-conditioning. This is sometimes referred to as climate control. ...
Psychrometrics is the measurement of the heat and water vapor properties of air. ...
The W16 engine from a Bugatti Veyron Mechanical engineering is a very broad field of engineering that involves the application of physical principles for analysis, design, manufacturing, and maintenance of mechanical systems. ...
Architectural engineers apply the skills of many engineering disciplines to the design, construction, operation, maintenance and renovation of buildings while paying attention to their impacts on the surrounding environment. ...
To meet Wikipedias quality standards, this article may require cleanup. ...
References - ^ Fundamentals volume of the ASHRAE Handbook, Ch. 27, ASHRAE, Inc., 2005
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