While “leaky” buildings ensure fresh air, they are also expensive to heat and cool. In order to reduce costs, architects design buildings to minimize this energy loss. While saving energy, this tight seal has the consequence of trapping in the mold, bacteria, and potentially harmful gasses like radon, VOCs (volatile organic compounds), and carbon dioxide. Prolonged exposure to these elements can lead to the phenomenon known as “sick building syndrome”, where occupants experience acute health and comfort effects linked to time spent in a building.
There are different methods to bring fresh air into a building. One way is to continually pump air in, which can run up high energy costs. A more energy and cost-effective method are to pump air in intermittently, only when it is needed. This can be done using CO2 sensors within the HVAC system; an example would be an Economizer with CO2 sensors.
Here’s how it works: when enough people enter a room, the CO2 level rises. The HVAC system responds by opening dampers, which allows fresh air in. When the people leave, the CO2 level drops, and the fresh air dampers are closed. Generally, 350 to 1000ppm is normal for inside an occupied building; when the level goes over 1000ppm, you can get complaints of drowsiness and poor air.
The Honeywell C7232 is a commonly used sensor and is preset at 500 to 1500 ppm and can be adjusted to a different range. When using C7232 with a Honeywell 7212 logic economizer control, there are two potentiometer adjustments: DCV set and DCV max. These two adjustments help you customize the environment to your specific needs.
The W7220, known as the Jade, also works with the C7232. The sensor has to be attached to the Jade control to be recognized; if you do not have a CO2 sensor none of the DCV parameters appear on the LCD screen. If you have a CO2 sensor, the “DCV MIN” and “DCV MAX” will appear and you can set accordingly.
The use of carbon dioxide sensors has many advantages, the most important of which is the improved air quality monitoring. Eliminate “sick building syndrome” and make your buildings healthier and more comfortable.
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