EEK! My office had high CO2 - how's your CO2?
Remember when the pandemic started? The last thing I was thinking about was my indoor air quality! As it turns out, as I worked from home, I realized my house had a stale air problem hurting my alertness and focus. This is my story of the causes, symptoms, and solutions of how we went from stale indoor air to mountain-fresh over the past year!
I noticed this past winter, after a few hours of working in my home office, I would feel fatigued… I’d open a window and let in some fresh air, and I would perk up. After a few weeks of this cycle, it got me thinking that something is happening here. I started researching what the issue could be… and the internet recommended buying a low-cost indoor air quality monitor to see what’s happening.
To my surprise, our CO2 levels would spike after working in my home office for a few hours.
C02 is a natural by-product of respiration; we take in Oxygen and exhale CO2. If you sit in a sealed box you’ll slowly consume all the Oxygen. As you use up the oxygen you’ll start to feel fatigued and groggy as the CO2 level increases. That’s what was happening in my house.
(CO2 should not be confused with carbon monoxide, CO, a combustion by-product that displaces air, and can kill you if you have a malfunctioning gas-burning appliance in your home.)
High CO2 levels are linked to poor concentration, loss of attention, impaired decision-making, and increased heart rate! A 2012 study concluded that a >1000 ppm level of CO2 had a detrimental impact on your ability to concentrate and act. Participants in this study took various computerized tests over several sessions that measured their performance at various CO2 levels. The results show that mental acuity is reduced even at relatively modest concentrations of CO2 over outdoor levels.
This chart from the 2012 study shows how performance is impacted even with gradual increases in CO2 levels. In most categories, like tasks & information usage, a 1000ppm significantly impacts cognitive skills… the kind of cognitive skills you want to use when working in your home office!
Figure: From 2012 study showing that even concentrations of 1,000 PPM of CO2 reduce your ability to execute basic tasks.
We Did This To Ourselves – Better Insulation & Air Sealing
My house is much tighter than it was the day it was built!
Over the past few years, I have significantly tightened up my house, improving insulation and air sealing every gap. First, we had our basement spray foamed, which acts as a vapor barrier, air sealer, and insulation. Second, this past August, we replaced our attic insulation, removed all of the existing insulation, spray foamed the deck [creating an air seal], and added 24 inches of cellulose insulation.
We set the stage for preventing fresh air from entering the house.
New houses built over the past few years are built very tight, and to get their certificate of occupancy, each house must have a blower door test and confirm that the house has limited air leakage with the outside. In Massachusetts’s climate zone, new construction must have no more than three air changes per hour. 3 ACHs per hour is not a lot of ventilation!
Everywhere you look, you’ll see utilities, governments, tv-shows repeating the mantra to “add insulation” and “seal up gaps” to save on heating & cooling. This is all true! You can save $ by tightening up your house and adding insulation. A tight house uses less energy with heating and cooling and is more comfortable with fewer hot & cold spots. A tight house prevents dust & allergens from sneaking into your house through small holes, like recessed lights or around outlets. And a tight house keeps insects from crawling in.
A tight house keeps fresh air from entering!
Picture: Last summer, my existing attic insulation got removed into giant vacuum cleaner bags. I air sealed and reinsulated the attic. The contractor filled 10 of these giant bags with the old attic insulation! Hot air can no longer escape through the attic during heating season. My attic has a new winter hat.
Picture: Before the attic project, I spray-foamed our basement. The concrete walls were insulated with closed-cell spray foam, and the wood-framed walls were insulated with open-cell spray foam.
Measuring the Problem
Qualitatively, I knew our air was stale in the house, and I could feel it when working in my office for a few hours. I could fix it by opening a window, and I’d feel better.
I wanted to measure the problem.
I bought the top-ranked air-quality monitor, an Airthings; it measures CO2, chemicals (VOCs), radon, temperature, and humidity. I popped in a few batteries, created an account, and started getting data. It was not good!
On a typical winter day in my office, my office’s CO2 levels spiked to 1,500 PPM.
Picture: Airthings air quality monitor I purchased for my office.
Houston, we have a problem!
Confirmed, we have high CO2… that’s why opening the windows in the middle of winter would make me feel better!
CO2 would spike two ways: it would steadily climb when I worked for several hours, and it would also spike when my family are home at night or on the weekend.
A typical workweek in my office:
Notice the elevated CO2 levels during the workday!
The irony of all this is that I solved one problem: making our house warmer and more comfortable by insulating & air sealing, But I had inadvertently created a new problem. No good deed goes unpunished!
The Solution
Now that I understood my problem and could measure it and feel it – it was time for solutions.
The answer is to install a machine that will help ventilate the house. This machine is called an Energy Recovery Ventilator, or an ERV for short.
An ERV is an air exchanger that runs 24 hours a day, taking stale, dirty air from your building and exchanging it with clean air from outside. What makes the device unique is the “energy recovery” part – the dirty air from inside the house and the clean air from outside pass each other through a plastic honeycomb – but never mix – and the two airstreams transfer their energy. You get the benefit of clean air, but the money you paid to heat or cool your indoors gets transferred to the incoming air… warming it up in the winter or cooling it down in the summer. ERVs are generally 70-80% efficient in transferring energy.
The ERV runs all the time, removing dirty air and bringing in clean air.
Picture: My new Panasonic ERV is installed in our utility room. An ERV has four connections to draw stale air out of the house and replace it with fresh outside air. A local HVAC company installed the unit and installed new ducts to draw stale air from several points within the house.
Once the ERV got installed and turned air, it felt like a new house! The air feels and smells fresh.
I feel much more alert when working in my home office, and my CO2 levels remain more reasonable at 500-800 PPM during a typical workday.
As a secondary benefit, on this multi-year air sealing and fresh-air odyssey, my house has no dust, no bugs creeping in, and my summer allergies are much better.
Fresh, Clean Air!
That’s my year-long story on how I improved the insulation & air sealing in our house. I reduced the air leakage in my house to such an extent, the indoor air would get stale, resulting in high indoor CO2 levels. By purchasing an air quality monitor and identifying the issue, I installed an ERV to improve my indoor quality.
If any of this sounds familiar, get an indoor air quality monitor and see if it tells a story… also, open a window!
About the Author: David Pabst, CPA/CITP (@datapabst), is a Director at the professional services firm Alithya and is an Oracle ACE ♠. David recently wrote the book The Nine Principles of Agile Planning: Create Nimble and Dynamic Forecasting in Your Organization, available at Amazon and other booksellers.