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Best Practice Guide |
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Local Governments |
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Central HVAC SystemNatural Ventilation and Air InfiltrationAll buildings need some sort of natural or artificial ventilation. Not only does proper ventilation prevent the buildup of harmful indoor air contaminants like mold, mildew, and soot, it also plays a big role in controlling indoor temperatures. Otfen, the best cooling is still as simple as opening a window. Large bay doors, clerestories, and/or windows are easily manipulated to allow outside breezes to push air into a building, forcing hot air upwards and out. In new construction or with major renovations, architects and engineers can model these airflow patterns and purposefully design apertures that maximize natural ventilation. Wind-driven ventilators can also be used. These use no energy, unlike their mechanical counterparts that use electricity to power a small motor. Wind-driven ventilators provide natural ventilation and help exhaust indoor air to the outside. With either natural or mechanical ventilation systems, free night cooling during warm summer months is an excellent no-cost way to lower energy use and stay cool. Open all air vents when nighttime temperatures drop so that the cool air can circulate and lower indoor temperatures. This technique is particularly suited to buildings with high thermal mass, such as those with concrete walls, since these buildings are slower to cool down, but slower, too, to heat up. Free cooling helps keep indoor temperatures comfortable even as outdoor temperatures rise. Air infiltration - basically, uncontrolled air leaks - is the opposite of natural ventilation. In the summer, hot outdoor air enters inside while cool, conditioned air escapes outside. In the winters, cold air enters and warm air escapes. Besides adding to HVAC loads, air infiltration causes uncomfortable drafts and may lead to the buildup of humidity. To avoid air infiltration, insulate carefully around all doors and windows and install weather stripping. Also check curtains and doorways around cold storage, process freezing, and other refrigerated areas. |