Clients call us regularly and ask, “What is the difference between a watt meter and a CO2 meter?” We can understand the confusion. Experts tell us that lowering energy use in our home results in a smaller carbon dioxide “footprint.” Since a watt meter can be used to help lower energy use, it follows that it might have something to do with also lowering CO2.
Technically, they might be right. Lowering watts does lower energy use, which does lower the need to produce energy. Less energy produced means less CO2. But that doesn’t mean a watt meter measures the same thing a CO2 meter does, nor does it mean they can be used interchangeably.
First, it helps to know what watt meters and CO2 meters actually do.
A watt meter measures the electric “power” in watts that an appliance uses in real time. You plug the watt meter into a wall outlet, then plug your appliance into the watt meter. The watt meter displays amount of power the appliance is using. This is important because some appliances continue to use power even when they are turned off.
By knowing the power every appliance in your home uses, you can make a plan to unplug wasteful appliances – or replace them – to lower the overall wattage you use each month.
So while a watt meter can tell you how much power an appliance is using, it doesn’t actually lower the wattage being used. That part is up to you.
A CO2 meter shows you the percentage of CO2 molecules in the air. Inside the meter is a carbon dioxide sensor. Inside the sensor is an infrared light. As the light passes through the air, the beam is defected by carbon dioxide molecules. The amount of deflection is proportional to the number of CO2 molecules in the air.
Like a watt meter, a CO2 meter can only tell you the current level of carbon dioxide at that moment. Lowering CO2 levels – like lowering watts used by appliances – is still up to you.
Should you have both?
You should purchase a watt meter (the Kill-a-Watt is popular) if you want to figure out how to lower your home energy costs, or as part of an overall strategy of lowering your personal carbon dioxide footprint.
CO2 meters that control your furnace or HVAC system can conserve energy. Rather than continuously “dumping” conditioned air, a carbon dioxide transmitter with relay can turn on the heat, fans, or air conditioners when people enter the room, and turn them off when they leave.
Studies have shown that CO2 - based air control can result in up to 50% energy savings.
You should also purchase a CO2 meter if you want to test CO2 levels in your home. High levels of CO2 trapped indoors can cause drowsiness or headaches. In addition, as CO2 levels rise, the quantity of volatile organic compounds (VOCs), odors and micro-organisms in the air rise too.