Economic conditions today dictate that all of us do what we can to conserve our valuable resources and design our spaces responsibly. In an effort to continuously improve the product we design and specify we sometimes incorporate design elements that enhance the operational capability of the space. One such effort we have incorporated recently has been the CO2 sensor.
Code requires that all HVAC equipment for commercial use be designed with outside air capability so that outside air can be introduced to the space. In addition, code also requires that this minimum outside air be circulated during all business hours regardless of actual occupancy of the space. This means that for a retail space with a 5,000 sq. foot sales floor the minimum outside per ASHRAE 1999 be 0.3 CFM per sq. foot or 1,500 CFM continuous. As you can imagine this can be extremely costly if your store is in Miami where you will be required to condition 1,500 CFM of hot, humid outside air the minute your store opens until the minute it closes in summer or heat the air in Minneapolis continuously in winter.
Code allows us, and this is especially necessary in the retail environment with the highly variable occupancy loads, to incorporate a CO2 detector to keep the outside air damper closed until the CO2 levels in the store rise to a predetermined level and then only that amount of outside air is introduced to not allow the CO2 level to exceed this value. As you can see this can lead to significant savings over the life of the HVAC equipment. In fact, Carrier produced a report in 2000 that can save 25% of the operating costs of rooftop equipment per year. ASHRAE printed a report showing that a department store in Tokyo saved 40% in the cooling system and 30% in the heating season.
The manufacturers have accepted the technology so well that they have incorporated the design into all their latest models as standard equipment. All that is required is a sensor that costs between $200.00 to $300.00. This information was obtained from Carrier and Lennox.
Code requires that all HVAC equipment for commercial use be designed with outside air capability so that outside air can be introduced to the space. In addition, code also requires that this minimum outside air be circulated during all business hours regardless of actual occupancy of the space. This means that for a retail space with a 5,000 sq. foot sales floor the minimum outside per ASHRAE 1999 be 0.3 CFM per sq. foot or 1,500 CFM continuous. As you can imagine this can be extremely costly if your store is in Miami where you will be required to condition 1,500 CFM of hot, humid outside air the minute your store opens until the minute it closes in summer or heat the air in Minneapolis continuously in winter.
Code allows us, and this is especially necessary in the retail environment with the highly variable occupancy loads, to incorporate a CO2 detector to keep the outside air damper closed until the CO2 levels in the store rise to a predetermined level and then only that amount of outside air is introduced to not allow the CO2 level to exceed this value. As you can see this can lead to significant savings over the life of the HVAC equipment. In fact, Carrier produced a report in 2000 that can save 25% of the operating costs of rooftop equipment per year. ASHRAE printed a report showing that a department store in Tokyo saved 40% in the cooling system and 30% in the heating season.
The manufacturers have accepted the technology so well that they have incorporated the design into all their latest models as standard equipment. All that is required is a sensor that costs between $200.00 to $300.00. This information was obtained from Carrier and Lennox.
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