Air Conditioning: Cooling AND Humidity Control!
May 28, 2013
After our first real blast of warmth this spring, it was interesting to note how many air conditioning inquiries we had. While peoples’ houses were no doubt uncomfortable – it is sometimes misunderstood what is needed. While some cooling would have no doubt helped their comfort level, a reduction in humidity was really what people were looking for. Sometimes it takes situations like this to realize how clever the pioneers of this field were – they didn’t call their new equipment house coolers (vs a heater); they named it air conditioning. That’s because the process “conditions” the “air” to make it more comfortable. Sometimes, it is predominantly cooling, others, it is a dehumidification.
When heating and cooling professionals size the equipment required to keep a house comfortable they perform a heating and cooling load calculation. On the cooling side, it calculates how much cooling capacity is required to keep a house at slightly under 24⁰ C (75 ⁰F) on one of the hottest days of the year. When you break down the number of hours we actually expect this to happen (based on historical weather statistics) it is actually less than 50 full days a year (in southern Ontario). We know from experience that most houses use their air conditioner much more than that. Why?
Its because of the other capability of an air conditioner – the reduction of humidity. In Southern Ontario, we happened to have fairly humid summers which can make it feel much warmer than it really is. Think about last week. How many hours was it actually above the level that needs cooling (24⁰ C/ 75⁰F)? Now think about your house – unless you have a lot of windows that face south or west (afternoon sun), your house was probably cooler than it was outside. Yet, there is no doubt, it was not comfortable late in the day until we went to bed. Why? Humidity. Think about early evening in the fall. The temperature has likely gone down well below 24 / 75. Yet we still need air conditioning. The warm air holds quite a bit of moisture which can make it seem much warmer than it is.
What’s the solution? Two-stage cooling equipment. It works magic when you don’t want the house to necessarily be cooler, just more comfortable. How does it work? Like the name suggests, the cooling function can perform at 2 levels. The A/C comes on at a reduced level to dehumidify and lightly cool. If, after a certain (short) period of time, the thermostat isn’t satisfied, the Air Conditioner goes into the second stage which cools (and dehumidifies) more aggressively.
Two stage Air Conditioners do cost more, but if the objective of installing an Air Conditioner is to ensure everyone is comfortable, you can not make a better choice – especially when it’s the humidity that’s making you feel uncomfortable!
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