Enter readings from your IAQ monitor or sensors. Leave any field blank to exclude it from the composite score. The score is calculated from the parameters you provide.
Parameter Breakdown
Full Results Table
| Parameter | Reading | Guideline | Score | Status |
|---|
How to Use This Calculator
Enter values from a multi-parameter IAQ monitor, individual sensors, or lab test results. You can enter as few as one parameter, and the calculator scores only the parameters you provide. Partial scores are still useful for identifying the worst-performing indicator.
Space type sets the per-person ventilation benchmark from ASHRAE 62.1-2022 Table 6-1 (residential uses the ASHRAE 62.2 per-person rate). If you enter a measured ventilation rate per person, the calculator flags whether it meets that rate. The floor-area part of the requirement is not included, so treat it as a screening check.
The composite score is the average of individual parameter scores, weighted so that PM2.5 and CO2 carry more influence given their broad health impacts. Each parameter scores 0 to 100 based on how the reading compares to its guideline threshold.
The parameter breakdown shows which indicator is dragging the composite score down most. This tells you where to focus improvement efforts, whether that's ventilation upgrades for CO2, filtration for PM2.5, or source control and ventilation for VOCs.
Composite IAQ Scoring: Putting the Full Picture Together
No single pollutant tells the complete story of indoor air quality. A space with excellent CO2 levels and poor PM2.5 filtration is still unhealthy. A space with clean air but excessive humidity is heading toward mold problems. Composite IAQ scoring aggregates multiple parameters into a single index that makes it easier to communicate overall air quality status, set priorities for improvement, and track progress over time.
Why CO2 Alone Isn't Enough
CO2 is the most popular IAQ indicator in Canadian buildings because it's cheap to measure continuously, correlates well with ventilation adequacy for occupancy loads, and responds quickly enough to be useful for demand-controlled ventilation. But CO2 only captures the occupancy-driven component of IAQ. A vacant building over a weekend can have excellent CO2 levels while accumulating formaldehyde from new materials, moisture from a plumbing leak, or PM2.5 infiltration during a wildfire event. CO2 monitoring is necessary but not sufficient for a full IAQ picture. The CO2 level calculator covers CO2-specific ventilation sizing in detail, and the demand-controlled ventilation calculator covers how ventilation can be modulated from a CO2 signal.
PM2.5: The Parameter with the Broadest Health Evidence
Fine particulate matter has the strongest and most consistent epidemiological evidence linking exposure to cardiovascular disease, respiratory disease, lung cancer, and premature mortality. Health Canada's guidance on PM2.5 in residential indoor air sets no numerical indoor limit. It says no threshold for health effects has been identified, so indoor levels should be kept as low as possible and at least lower than outdoors. This calculator scores PM2.5 against the WHO 2021 24-hour guideline of 15 µg/m³ as a practical yardstick. During wildfire smoke events, indoor PM2.5 rises with outdoor levels, and a building without good filtration will see its score fall quickly. PM2.5 monitoring is an important addition to any basic CO2-only IAQ monitoring setup. The PM2.5 calculator models indoor concentration from outdoor levels and filtration.
TVOC and Formaldehyde in New Canadian Construction
Total VOC and formaldehyde scores are most relevant in the months after construction, renovation, or significant furnishing. New MDF cabinetry, laminate flooring, and pressed-wood furniture emit formaldehyde that can push it above Health Canada's 50 µg/m³ long-term guideline, and TVOC from adhesives, paints, and flooring can run far higher in the first weeks of occupancy, as the New Construction example shows at 2,200 µg/m³. Health Canada sets no TVOC guideline, so the 500 µg/m³ used here is a screening value. Programs such as LEED include pre-occupancy flush-out or air testing options for this reason. The formaldehyde calculator and VOC calculator size the ventilation needed to manage these sources.
Humidity as an IAQ Parameter
Relative humidity affects multiple IAQ outcomes simultaneously: mold growth risk on surfaces, dust mite populations, respiratory comfort, and formaldehyde emission rates from building materials, which increase with temperature and humidity. Both too-low and too-high humidity reduce IAQ composite scores, and this calculator scores RH against a 30 to 50% range. Health Canada recommends 30 to 35% in winter and below 50% in summer, and both winter under-humidification and summer over-humidification are common in the same Canadian building across the year. The humidity comfort calculator and mold risk calculator cover humidity-specific assessments in more depth, and the dew point calculator shows the surface temperature below which condensation forms at a given RH.
Ventilation Rate as an IAQ Parameter
Measured ventilation rate per person directly determines the dilution capacity available for all occupancy-generated pollutants. A space scoring well on all pollutant measurements but at a ventilation rate below the minimum for its occupancy type is at risk of degrading quickly under full design occupancy. Including ventilation rate in the composite score provides an early warning before pollutant levels actually exceed guidelines. The calculator compares the measured rate with the per-person rate in ASHRAE Standards 62.1 and 62.2: 2.5 L/s for office space, 5 L/s for classrooms, 3.8 L/s for retail, 10 L/s for health club and aerobics rooms, and 3.5 L/s per person for homes. Full 62.1 compliance also adds an area component and applies zone effectiveness, so treat this as a screening check. The National Building Code of Canada refers to ASHRAE 62.1 in Part 6 for ventilation.
Frequently Asked Questions
IAQ scores vary by the rating system used. As a practical benchmark, a space with CO2 below 1,000 ppm, PM2.5 within WHO's 24-hour guideline of 15 micrograms per cubic metre, relative humidity between 30 and 50 percent, and no significant VOC or formaldehyde sources would score in the Excellent or Good range on this calculator's composite index. For reference, Health Canada's long-term formaldehyde guideline is 50 micrograms per cubic metre and its CO2 limit for homes is 1,000 ppm as a 24-hour average, and it advises keeping indoor PM2.5 as low as possible. The bands used here are 90 to 100 Excellent, 75 to 89 Good, 60 to 74 Acceptable, 40 to 59 Poor, and below 40 Very Poor.
Fine particulate matter PM2.5 is generally considered the most broadly harmful indoor air pollutant because it penetrates deep into the lungs and can enter the bloodstream, contributing to cardiovascular disease, respiratory disease, and cancer with long-term exposure. Carbon monoxide is the most acutely dangerous at high concentrations, capable of being fatal within hours. For cognitive performance and productivity, some controlled studies report effects from CO2 at concentrations reachable in normal occupied buildings, starting around 1,000 ppm, although results are mixed. VOCs and formaldehyde are significant concerns in new construction and renovation scenarios. A composite approach matters because the parameters can fail independently: a space can have good PM2.5 levels but still be unhealthy due to high CO2 or humidity.
Continuous monitoring of CO2 and temperature is common practice in commercial buildings, and CO2 sensors connected to building automation can provide real-time demand-controlled ventilation signals and alert facility managers when CO2 climbs above roughly 1,000 ppm. How often to test the other parameters depends on the building: sooner after renovations and more often in buildings with known issues or vulnerable occupants such as schools and healthcare facilities. Low-cost multi-sensor IAQ monitors have made continuous monitoring practical even for smaller commercial spaces and residential applications. Health Canada also recommends a professional inspection of fuel-burning appliances at least once a year, which matters for carbon monoxide.
TVOC stands for Total Volatile Organic Compounds, a collective measurement of all VOC gases present in indoor air, typically in micrograms per cubic metre. Common indoor VOC sources include paints, adhesives, cleaning products, furniture, flooring, and personal care products. Health Canada does not set a single TVOC guideline but does set guidelines for individual compounds such as formaldehyde, so this calculator uses 500 micrograms per cubic metre as a screening value. TVOC sensors measure a broad response to VOC gases and are useful as a relative indicator of air quality trends, but they can't identify which specific compounds are present. A space with high TVOC from cleaning products has different health implications than the same reading from building materials, which is why specific compound testing is needed for detailed assessment.
Related Air Quality Tools
CO2 from occupancy and ventilation
Indoor PM2.5 from filtration and infiltration
Ventilation for VOC off-gassing
Off-gassing and ventilation sizing
Comfort zone and condensation risk
AQHI from raw pollutant readings