![]() Even though the temperature has not changed, the movement of air across our skins causes evaporative cooling. ![]() We can be quite comfortable outside until the wind picks up. ![]() With the warmth emanating from a radiant floor, we can experience the same level of comfort with the thermostat set a few degrees lower than needed in a forced air home.īlowing hot air paradoxically can cool us This is because the radiant warmth from the sun allows us to be comfortable at a lower air temperature. When we are outside on a warm, sunny day, we may be comfortable in a tee shirt even if the air is only 60 degrees. Lower air temperatures for the same comfort Or rooms facing direct sunlight become overheated while other rooms are inadequately controlled. The result is a top story that’s too hot, while downstairs remains cool. This is because forced air systems are inherently difficult and therefore, expensive to zone. In other words, they are single zone systems. Most forced air homes have a single thermostat. It is precisely because of this effect that we insulate ceilings and attics so much. In addition, when ceilings are hot and just below a cold roof, heat loss is quite high. This stratification effect becomes greater as the ceiling height increases. This hot air rapidly rises, creating a temperature zone that can often be over 10 degrees warmer than the air below. All of these parasitic losses add up in forced air systems to a 30% less efficient system.įorced air systems emit hot air at a temperature of approximately 120–140 degrees Fahrenheit. Blowers used in forced air systems on average require 9x the amount of electricity as the pumps in radiant systems. This pressure pushes the heat through weather stripping on windows. As hot air is blown through these large ducts, heat is lost through the tiny flaws in the system and escapes into unknown areas.Īdditionally, when hot air is blown into a room with a door closed, it can cause an increase in air pressure. Duct work in a forced air heating system, for example, can be difficult to permanently seal/insulate and is often located in unheated crawl spaces or basements. Parasitic loss refers to energy lost due to inherent inefficiencies of a system. * 1998 study by Kansas State University and the American Society of Heating Refrigeration and Air-Conditioning Engineers ) This savings can be further increased if using high efficiency heat sources in conjunction with the radiant heat system. A typical radiant heated home in the US can expect a 25%* energy savings over a conventional forced air home due to a variety of factors that are explained below.
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