Model multi-stage filtration systems with pre-filters and final filters. Calculate overall system efficiency, pressure drop stack, and particle removal by size fraction from MERV 8 through HEPA.
Size standalone air purifiers from room volume and target ACH. Calculate CADR needed for smoke, dust, and pollen. Covers portable units and whole-home systems.
Convert raw pollutant concentrations (PM2.5, PM10, O3, NO2, SO2, CO) to AQHI and AQI values. Compare indoor readings against Environment Canada AQHI categories and outdoor reference levels.
Calculate CO buildup from combustion appliances in enclosed spaces. Estimate time to hazardous concentrations and minimum ventilation to stay below Health Canada's 11 ppm guideline.
Calculate steady-state indoor CO2 from occupancy, metabolic rate, and outdoor air flow. Verify against ASHRAE 62.1's 700 ppm above outdoor limit and size OA to hit any target concentration.
Calculate combustion air requirements for gas furnaces, boilers, and water heaters per NBC and CSA B149.1. Size makeup air openings and assess backdrafting risk from depressurization.
Calculate outdoor air flow needed to dilute any contaminant to an acceptable concentration. Covers solvents, CO2, formaldehyde, VOCs, and combustion products per ACGIH and Health Canada limits.
Estimate indoor formaldehyde concentration from off-gassing materials and ventilation rate. Compare against Health Canada's 50 µg/m³ long-term guideline and size OA to achieve compliance.
Calculate HEPA filter performance for particles down to 0.3 µm. Estimate required face velocity, pressure drop, and service life from airflow, room volume, and particle load.
Calculate the ASHRAE 55 comfort zone from temperature and relative humidity. Assess mold risk, dust mite activity, and respiratory comfort across indoor conditions.
Score overall indoor air quality from CO2, VOC, PM2.5, humidity, and ventilation rate. Get a composite IAQ index with pass/fail against ASHRAE 62.1 and Health Canada guidelines.
Size bipolar ionization and needlepoint ionization systems for commercial and residential spaces. Calculate ion output needed per volume and verify ozone output stays below 0.05 ppm Health Canada limit.
Compare filter efficiency across MERV 8 through MERV 16 and HEPA. Calculate particle capture rates by size, pressure drop penalty, and impact on system static pressure.
Assess mold growth risk from surface temperature and ambient RH. Calculate surface relative humidity from indoor conditions and wall assembly R-value. Flags risk above 80% surface RH.
Estimate indoor PM2.5 concentration from outdoor levels, infiltration rate, and filtration. Compare against Health Canada's 24-hour guideline of 10 µg/m³ and WHO annual target of 5 µg/m³.
Model indoor pollutant buildup and decay from any source rate, room volume, and ventilation. Works for CO, CO2, VOCs, PM2.5, and custom contaminants with time-to-threshold output.
Calculate sub-slab depressurization fan sizing for radon mitigation. Estimate airflow and pressure field extension from foundation type and soil permeability. Uses Health Canada's 200 Bq/m³ guideline.
Size UV-C germicidal irradiation systems for AHUs and upper-room air disinfection. Calculate required dose for 99.9% inactivation of bacteria, mold spores, and viruses.
Calculate ventilation effectiveness (Ev) and air change effectiveness (ACE) from supply air distribution type and room geometry. Apply ASHRAE 62.1 Ev factors for mixed, displacement, and stratified flow.
Calculate ventilation needed to dilute VOC emissions from new construction materials, furniture, and finishes to Health Canada and WHO guideline levels.
Indoor Air Quality Tools for Canadian Homes and Buildings
Indoor air quality has moved from a niche building science topic to a mainstream concern for Canadian homeowners and HVAC professionals alike, driven by wildfire smoke seasons, tighter building envelopes, and growing awareness of how much time we spend indoors. These 20 calculators cover the full range of IAQ assessment: pollutant-specific tools for CO2, PM2.5, VOCs, formaldehyde, carbon monoxide, and radon; filtration sizing for MERV, HEPA, and multi-stage systems; ventilation calculators for dilution air, combustion air, and ventilation effectiveness; and humidity-driven tools for mold risk and comfort assessment.
Where to Start
- For an overall snapshot, start with the IAQ calculator, which combines CO2, PM2.5, VOC, humidity, and ventilation into one composite score.
- During wildfire smoke season, use the PM2.5 calculator and air purifier sizing calculator together to plan filtration response.
- For new construction or renovation off-gassing, check the VOC calculator and formaldehyde calculator.
- If you've tested for radon above 200 Bq/m³, the radon mitigation calculator sizes the sub-slab depressurization system.
- For HVAC filter upgrades, compare options with the MERV rating calculator before committing to a MERV 13 retrofit.
Frequently Asked Questions
A space with CO2 below 1000 ppm, PM2.5 below 10 µg/m³, relative humidity between 30 and 55 percent, and no significant VOC sources scores in the Excellent range on most composite indices. RESET Air, used in Canadian commercial certification, rates IAQ as Good above 75 and Excellent above 90 on its 0-100 scale. Use the IAQ calculator to get a composite score from your own sensor readings.
ASHRAE 62.1 targets indoor CO2 no more than 700 ppm above outdoor levels, roughly 1,100 ppm under current outdoor conditions of about 420 ppm. Research shows cognitive performance begins to decline measurably at 1,000 ppm, which is why many Canadian schools and offices target 1,000 ppm as a practical ceiling rather than the looser 1,100 ppm code minimum. Use the CO2 level calculator to check your space against occupancy and ventilation rate.
Health Canada recommends remedial action when the average annual radon concentration in normal occupancy areas exceeds 200 becquerels per cubic metre. Between 200 and 600 Bq/m³, action should happen within two years. Above 600 Bq/m³, action should happen within one year. Testing should run a minimum of 3 months, ideally during fall or winter. Use the radon mitigation calculator to size a sub-slab depressurization system for your specific soil type and foundation.
A furnace filter upgrade (MERV 13 or better) cleans all air circulating through your HVAC system whenever the fan runs, providing whole-home protection. A portable HEPA purifier cleans air in one room continuously, independent of furnace cycling — useful for bedrooms during sleep or homes without mechanical ventilation. During wildfire smoke events, combining both provides the strongest protection. Compare options with the MERV rating calculator and air purifier sizing calculator.
Absolutely — all AskHVAC.ca tools are fully responsive and work on any smartphone or tablet without an app install. They run entirely in your browser with no internet connection required after the page loads. Results can be exported to PDF or CSV directly from your phone. Use them freely at the job site, in the truck, or in the office.