Energy Consumption in Commercial HVAC Systems
Updated: May 12, 2022
In the United States commercial sector, there are 6 million buildings that account for 97 billion square feet of floor space. Considering how much time people spend in buildings for work, education, healthcare, or retail, it is paramount to ensure that occupants are healthy and comfortable indoors. Over 90 percent of total commercial floor space uses some form of a mechanical heating and cooling system, so it is not surprising to see that heating, cooling, and ventilation is, on the national average, the single greatest contributor to total energy needs for commercial buildings. Thirty-five percent of energy usage goes toward heating and cooling efforts, and ventilation accounts for another sixteen percent. Heating, ventilation, and air conditioning (HVAC) systems are deployed in buildings to provide adequate levels of indoor ventilation while providing thermal comfort for occupants, and as a result, the average-size American commercial building spends over $15,000 on HVAC-related costs. This number varies greatly with building size and HVAC use.
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Air Changes and Efficiency
Because commercial buildings require so much energy to keep temperature, humidity, outside air, and occupant comfort in check, there is much interest in potential ways to conserve energy in these processes. In general, there are two ways to conserve energy in a commercial building. One is to reduce the amount of air changes per hour, and the other is to increase energy efficiency, either by limiting unnecessary usage of certain equipment or various other means. The rate of air changes per hour is the average measure of how many times the air in a system is exhausted and replenished.
Air changes can be an efficient way of decreasing the amount of unwanted pollutants in the air, whether it be CO2 or any airborne contaminant. For example, if there are two air changes per hour in a commercial building, it would take over two hours to remove some fixed amount of contaminants from a building at a 99% efficiency. If the rate of air changes is raised to six per hour at the same efficiency, that time would be cut down to just 46 minutes. This system works by dilution, as outside air volumes can be added to lessen the amount of undesirable particles in the air. If there was some assembly or gathering of people in a school auditorium, the increased amount of people in one place would likely result in an increase of the amount of CO2 in the air. The HVAC system would then have to increase the amount of outside air in the system to lessen the amount of CO2. Increasing the amount of air changes could even lessen the chance for airborne disease transmission in commercial buildings. However, large increases in air volume and changes require a great amount of energy, causing energy bills and carbon footprints to rise.
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What if there was a different way to conserve energy in a building without sacrificing the health benefits that come with replenishment of air in a system?
Reducing Indoor CO2 Levels with Carbon Reform
Capturing CO2 from indoor air poses major benefits, both from energy use and health perspectives. The risks of high CO2 levels in buildings are abundant, including sick building syndrome, and high CO2 levels can indicate alarming levels of other materials that can accumulate like viruses or toxic particulate matter. If meaningful levels of CO2 can be reduced in commercial buildings, economic benefits directly related to occupant health improvements could be seen in excess of nine billion dollars across the sector. The economic value of addressing sick building syndrome in commercial buildings includes 10 million avoided sick days and increased overall productivity in the workplace from a lowered risk of sick building syndrome.
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In addition to health and work benefits, there is also an economic benefit to capturing CO2 in commercial buildings. Many HVAC systems work as recirculating air pumps, taking air from the outside, heating or cooling it in some way, and then pushing it throughout the building. It is important that fresh, outside air is present within the intake for the system. Air also needs to be cycled out of the building, for it quickly can become saturated with CO2 and other pollutants that can affect air quality within the building. If CO2 can be collected during air circulation, less air changes per hour may be needed, and about half of a building’s HVAC-related costs can be cut, saving 38 billion dollars across the country.
Removing CO2 from commercial ventilation systems will deliver massive energy savings while also providing health benefits for building occupants. Carbon Reform’s modular capture device, named the Carbon Capsule, works to scrub CO2 from a building’s ventilation system while being adjustable to fit any unique air handler. Our goal is to capture and remove CO2 from commercial HVAC systems in order to be converted into calcium carbonate and used in other capacities, all while running a carbon-neutral or carbon-negative process. With the Carbon Capsule, a positive cycle of health, environmental, and office productivity benefits can be achieved while captured CO2 is converted into sustainable materials that are good for the Earth.
To learn more about our mission of clean air for people and planet, visit our website: www.carbonreform.com.