Why Your Home Feels Stuffy (and What a CO2 Reading Can Tell You)
Ever walk into a home and notice the air feels heavy or stale, even though the place is spotless? Nothing looks wrong. The AC is running. But something about the air just feels used.
It is not necessarily a sign that something is broken. Often, it comes down to how much fresh air the home gets.
What is going on in there
Many modern homes are built fairly tight to keep the heat and humidity out. That is good for your energy bills. A standard air conditioning system cools and recirculates the air already inside the house. It does not bring fresh air in from outside on purpose.
Add windows that stay shut most of the year, and the air you breathe out has nowhere to go. Throughout the day, it can slowly build up. The gas we are talking about is carbon dioxide, or CO2. Every person in the house breathes it out.
What we see in the field
When we do mold inspections, we measure the air in the home, including CO2. Outdoors, it sits at a little over 400 parts per million (ppm). Inside the homes we inspect, during the day, we often see readings from about 1,400 up to nearly 1,900 ppm.
In one recent mold inspection, our meter showed 1,854 ppm of CO2, while a second meter showed almost no fine dust particles in the air. In other words, the air was clean, but it was stale.
To keep that in perspective: the workplace safety limit set by OSHA is 5,000 ppm, so these readings are well under it. This is not an emergency. These are also homes where someone asked us to look closely at the air, so it is not a survey of every home.
Why it matters
In a small 2012 study from Lawrence Berkeley National Laboratory and SUNY Upstate Medical University, 22 people took decision-making tests in a room set to different CO2 levels. At 1,000 ppm, their scores dipped moderately on six of nine measures compared with a fresher room. The researchers said more studies were needed, so this is not settled science. It is still a good reason to pay attention to fresh air.
A home that is not bringing in much fresh air is also not diluting anything else that builds up indoors.
What you can do about it
Here are some simple steps, starting with the easiest:
Open windows briefly on mild, dry days to let fresh air in.
Run your bathroom fans on a timer so stale air has a way out.
Ask an HVAC contractor about fresh-air ventilation. One option is an energy recovery ventilator, or ERV. It brings fresh outdoor air in while limiting how much humidity comes with it, which matters a lot in Florida.
Concerned about the air in your home?
If you are worried about moisture, mold, or just air that never feels fresh, a mold inspection from Hanna Home Services looks closely at what is going on in the air and in the home. We are a licensed mold inspector, and we do not do remediation, so we have no reason to sell you cleanup. Learn about our mold inspections
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