The purpose of ventilation is to ensure the continuous availability of fresh air in a building. This is often done by bringing outdoor air into the indoor spaces through ventilation systems which are usually tied to the building’s heating and air conditioning system.
The use of ventilation in a building supports the health and well-being of occupants, but it can lead to some incredible energy waste. That’s because the heating and cooling systems are working hard to condition the air already in the building. If the ventilation system keeps replacing the conditioned air, those other systems must work hard to keep the room at a constant temperature.
Here are three ways building owners or facility managers can reduce ventilation system energy waste. When combined, they can increase occupant comfort while saving big bucks on the building’s energy bill.
Install Demand Sensors
There are different types of demand sensors, depending on the application, but the most common type measures the level of carbon dioxide in a room or building. Once carbon dioxide levels reach a pre-determined level, the sensor tells the ventilation system to increase air flow. The incoming air replaces existing air and decreases carbon dioxide levels.
While most ventilation systems run continuously, demand sensors allow the ventilation system to shut off when not needed. This saves energy both in running the ventilation system and in heating or cooling the replacement air.
Use Indoor Plants
Once a building has demand sensors in place, the next thing that can be done is to reduce the carbon dioxide levels in the building – naturally. Plants can be placed throughout the building to reduce carbon dioxide levels while increasing the availability of oxygen for occupants.
Kamal Meattle, in his “How to Grow Fresh Air” presentation at TED 2009, suggests that indoor plants can be used in a building to remove carbon dioxide and other toxins. He proposes that the proper use of certain plants, including the Areca Palm, can not only reduce the need for ventilation but could even provide enough oxygen that ventilation won’t be needed at all.
Install Heat Exchangers
Another way to reduce the amount of heat lost through ventilation is to install a heat exchanger on the building’s ventilation system. Heat exchangers remove heat from out-going waste air and transfer that heat to incoming fresh air.
This method of heat transfer helps reduce the demand placed on heating and cooling systems, saving even more energy.
There are two types of heat exchangers commonly available: Heat-Recovery Ventilators and Energy-Recovery Ventilators. The benefit of an Energy-Recovery Ventilator is that it helps keep humidity levels at desired levels by transferring some of the air’s moisture content along with the heat being transferred.
While each of the above suggestions will help improve indoor air quality, combining all three of them could generate huge improvements. First, ensure the building ventilation system is only on when needed. Then, use plants to reduce the amount ventilation needed. Finally, take the heat (or chill) out of outgoing air and transfer it to incoming air.
If a building or facility manager uses this combination in their building(s), they can experience drastic reductions in heating and cooling energy bills.