The amount of time the pressure is present.The magnitude of pressure across the hole.
The amount of air that flows through a hole is limited by three factors:
Limiting Factors to Air Flowįlow Determinants. Leaks in a building’s air-distribution system are also uncontrolled air flow. This can be caused either by wind, by the force of heated air rising within the building, or by out-of-control fans. Uncontrolled air flow is any non-designed movement of air into, out of, or within a building. Ventilation systems, fans, spot ventilators, make-up air, and heating and air conditioning system flow are typical sources of controlled air flow. Controlled Versus Uncontrolled Air Flow Controlled Air FlowĬontrolled air flow is generated by a mechanical device and is designed to help ventilate a building and/or distribute conditioned air throughout a building. In either case, the actual flow of air is determined by several factors, including hole size, resistance to flow, and pressure effects. Air flows within buildings are either controlled or uncontrolled. In order for air to flow into, out of, or within a building, two requirements must be met: a hole or path must exist for the air to flow through, and there must be a driving force. This section examines the forces and conditions that allow air to flow into, out of, or within a building, including: Many different factors control how air flow affects a house. In simplest terms, air needs an opening or hole to flow through and a driving force to move it. This introduction defines many of the theories behind the ENERGY STAR New Homes requirements. This introduction focuses on three particular areas:įor each of these issues, the introduction explores causes, control measures, and effects on both buildings and occupants. Many aspects of building design, construction, and operation can affect the health and comfort of the people in the building.
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