Carbon dioxide indoors
Every exhale adds CO₂ to a room. Rising readings can help you spot when ventilation is falling behind occupancy; they do not diagnose symptoms or concentration problems.
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13–13 of 13 guides
Bedroom overnight: the CO₂ climb you sleep through
Two adults in a closed bedroom can push CO₂ past 2,000 ppm by 4 AM. The math is unforgiving.
ASHRAE ventilation rates: the math behind "open a window"
ASHRAE 62.1 covers commercial; 62.2 covers homes. Both give you a number in CFM per person.
Wind and infiltration: how the outdoors gets in
Outdoor wind drives air through small cracks and gaps in your building. Higher wind = more outdoor air entering, whether you want it or not.
Open vs. closed windows
The single most consequential daily decision the dashboard helps you make. Six outdoor signals, three indoor signals, one answer.
Demand-controlled ventilation
Run the HVAC harder when people are in the room, less when they aren't. CO₂ sensors are how it knows.
Building type priors
Apartments, townhomes, detached single-family, and commercial buildings each have characteristic air-quality patterns. Knowing yours helps you read the numbers.
Ventilation approaches, compared
Open windows, range hood, HRV/ERV, demand-controlled ventilation. Different ways to bring fresh air in and stale air out.
Reducing CO₂ indoors: the ventilation ladder
CO₂ is what people exhale. The only durable answer is moving more outside air in. First find out why it stays high, then work the cost-ordered ladder, from free to capital project.
Spot ventilation: kitchen and bath exhaust done right
Task-specific exhaust handles the worst pollutant sources at their origin. Sized correctly and ducted to outdoors, it does more than whole-house ventilation can.
Office IAQ: the 4 p.m. conference-room problem
A typical office starts the day near the outdoor CO₂ level and ends it well above 1,000 ppm in the meeting rooms, plus VOCs from cleaning and new furniture and whatever the outdoor air brings in.
IAQ tradeoffs with energy: ventilation has a heating bill
Every cubic foot of outside air you bring in is air you have to heat or cool. In some climates "just open windows" is correct; in others it is the most expensive intervention you can pick.
CO₂ sensor accuracy and ventilation
CO₂ is the clearest occupancy and ventilation signal in most rooms, but placement, calibration assumptions, and recovery time still shape the interpretation.
