Before a building can improve indoor air quality, it needs a trustworthy starting point. A baseline study records how air actually behaves across zones and times of day, using a sampling plan, suitable sensors and a clear report format. Without it, later improvements cannot be proven and ventilation problems may go unnoticed. ASHRAE 62.1 provides the ventilation framework many commercial buildings follow, and a baseline shows how your spaces perform. To plan a study for your own building, you can talk through a baseline scope with our specialists.
HVAC indoor air quality monitoring
Start Every IAQ Program With a Baseline You Can Defend
iFactory AI helps commercial buildings plan sampling, choose sensors and report results so improvements can be measured against a clear starting point.
What a baseline typically records
Carbon dioxideParticulatesTemperatureHumidityOccupancy
Why start hereWithout a Baseline, Every Fix Is a Guess
Complaints arrive, a quick fix is tried and nobody can say whether air actually improved.
Complaint arrives
Stuffy, warm or smelly space
Quick fix tried
Damper or setpoint changed
No proof
No before reading to compare
Problem returns
Same complaint next month
A baseline turns opinion into evidence. It shows what is normal, what is a problem and what changed after action.
Sampling planFive Steps to a Plan That Holds Up
1
Define the goal
Compliance check, complaint response or portfolio benchmark.
2
Choose zones
Cover each air handler, space type and known problem area.
3
Pick the period
Sample long enough to include occupied and quiet times.
4
Set the interval
Frequent enough to catch peaks without flooding data.
5
Document conditions
Record occupancy, weather and any ventilation changes.
A written plan is what makes the result defensible to owners, tenants and auditors.
Sensor selectionMatch the Sensor to the Question You Need to Answer
| Parameter | Why measure it | Selection note |
|---|
| Carbon dioxide | Useful indicator of ventilation per person | Check sensor type and calibration method |
| Fine particulates | Shows filtration and outdoor air quality effects | Choose a reliable, consistent sensor |
| Temperature | Comfort and equipment behaviour | Place away from direct heat sources |
| Relative humidity | Comfort and mould risk | Verify accuracy range |
| Occupancy or schedule | Explains why readings change | Use badge, count or schedule data |
ASHRAE 62.1 sets ventilation requirements rather than a single carbon dioxide limit. Carbon dioxide is often used as an indicator, so interpret it with care.
Get a Baseline Plan That Fits Your Floors
Share your building layout and concerns and see how iFactory AI can outline zones, sensors and a sampling schedule.
PlacementWhere to Put Sensors for Readings That Mean Something
Poor placement gives confident but wrong numbers.
Breathing height
Place sensors where people actually breathe, away from vents and doors.
Representative rooms
Choose typical spaces as well as the worst ones.
Return air
Use return air as a check, not a replacement for space readings.
Outdoor reference
Record an outdoor reading to interpret indoor results.
Dense areas
Include meeting rooms and other high occupancy zones.
Avoid hot spots
Keep sensors away from sun, heaters and equipment exhaust.
Good placement saves rework later. To review your floor plans, ask our team for a placement checklist.
ReportingA Report Format Decision Makers Will Actually Read
Summary
One page with the main finding and recommended action.
By zone
Results for each space with simple pass or review marks.
Time patterns
Daily and weekly patterns that explain peaks.
Exceptions
Zones that need follow-up and the data behind them.
Keep the language plain and the charts few. The report is a tool for action, not a data dump.
Illustrative resultReading a Zone Summary From a Baseline
Example: share of occupied hours within target range
These bars are an example only. Targets should be agreed in advance and tied to your ventilation design.
Stated goal for the study
Zone list with air handler mapping
Sensor list with calibration records
Sampling period and interval
Outdoor reference source
Report format and audience agreed
Ventilation contextWhat ASHRAE 62.1 Means for a Baseline Study
ASHRAE 62.1 is a ventilation standard for acceptable indoor air quality. A baseline helps you see how your building operates against that intent.
1
Outdoor air requirements
The standard sets minimum outdoor air based on space type, floor area and occupancy.
2
Ventilation rate procedure
A common prescriptive route that calculates required airflow for each zone.
3
IAQ procedure
An alternative route that uses measured or modelled contaminant levels.
4
Design versus operation
Systems designed correctly can still operate poorly, which is where monitoring helps.
5
Documentation
Records of design basis and operation support audits and reviews.
This guide is not a substitute for the standard or professional advice. Confirm requirements with your engineer and local code.
Common pitfallsMistakes That Weaken a Baseline Study
Most weak studies fail for avoidable reasons. Planning around these pitfalls keeps the result credible.
Weak study
One day of sampling
Sensors dropped in convenient spots
No outdoor reference
Results shown without context
Strong study
Several weeks across seasons if possible
Sensors placed to a written plan
Outdoor data recorded alongside
Results tied to occupancy and schedule
A defensible study also records calibration dates and any changes made to the ventilation system during sampling.
Reading resultsTurn Readings Into Three Clear Outcomes
Decision makers do not want raw numbers. They want to know where things are fine and where action is needed.
Within target
Readings stay in the agreed range during occupied hours.
Needs review
Occasional peaks or patterns that deserve a closer look.
Act
Frequent or sustained excursions that need a fix.
Agree the target ranges before sampling begins, so results are not judged after the fact.
Time patternsAir Quality Changes Across the Day and Across the Year
A single snapshot misses how a building behaves. Patterns explain most complaints.
Morning start-up
Ventilation ramps up and early occupants arrive
Midday peak
Occupancy is highest and carbon dioxide tends to rise
Afternoon heat
Cooling load and outdoor conditions change airflow
After hours
Systems idle and readings fall back to a quiet baseline
Include weekends and holidays in the sampling period, since low occupancy can expose ventilation and scheduling issues.
After the baselineFive Follow-Up Actions That Turn Data Into Better Air
A baseline only has value when it leads to action. These are the usual next steps.
Fix scheduling
Align ventilation start and stop times with real occupancy.
Adjust outdoor air
Review minimum outdoor air settings in problem zones.
Improve filtration
Check filter grade, condition and replacement schedule.
Tackle hot spots
Investigate zones with repeated excursions.
Repeat and compare
Re-measure after changes to prove improvement.
Repeat the study after major changes and at least once a year. To plan your follow-up programme, ask our team for an action tracker.
From reading to decisionHow a Sensor Reading Becomes an Action
Raw readings only matter if they lead somewhere. A simple chain keeps the process clear.
1
Measure
Sensors record air quality, temperature and humidity.
2
Compare
Readings are checked against agreed targets and the baseline.
3
Diagnose
Patterns point to causes such as scheduling or filtration.
4
Act
The team adjusts, repairs or investigates, then re-measures.
Close the loop every time. An action without a follow-up reading leaves you guessing whether anything improved.
Monitoring maturityFour Stages From Spot Checks to Continuous Insight
Most buildings start small and grow. Each stage gives more insight and costs more effort.
Stage 1: Spot checksHandheld readings after complaints
Stage 2: Periodic surveysPlanned baseline studies once a year
Stage 3: Continuous monitoringPermanent sensors and live dashboards
Stage 4: Responsive ventilationReadings help adjust ventilation automatically
A baseline study is the natural bridge between stage one and stage three, because it shows where permanent sensors are worth installing.
Complaint sourcesWhat Usually Sits Behind Indoor Air Quality Complaints
Knowing common causes helps shape the baseline plan. This split is an illustrative example.
35 percent: Ventilation
Too little outdoor air or poor distribution.
25 percent: Temperature and humidity
Comfort problems often reported as air quality.
20 percent: Filtration
Worn or low-grade filters and dirty coils.
20 percent: Local sources
Cleaning products, printers, construction or odours.
Many complaints blend several causes. A baseline helps separate them so the right fix is chosen.
Reading carbon dioxideCarbon Dioxide Is Most Useful When Read With Occupancy
A high reading means different things depending on how many people are in the space.
Reading context
Occupancy high
Occupancy low
Carbon dioxide high
Check airflow
May show too little ventilation per person
Investigate
Unexpected. Check sensor, schedule or source
Carbon dioxide low
Likely fine
Ventilation looks adequate for the load
Check for overventilation
Energy may be wasted in quiet spaces
Treat carbon dioxide as one indicator. Combine it with particulates, temperature and complaint history for a fuller picture.
What to put on page oneFour Numbers That Summarise a Baseline Report
Leaders want the headline quickly. Four simple figures tell most of the story.
Zones
Number of zones covered
Hours
Total sampling hours
In range
Share of occupied time within target
To fix
Zones needing action
Put detail in appendices for engineers. To see a sample page one, review an example report with our team.
Expert reviewWhat an Indoor Air Quality Specialist Would Check First
Expert review
A baseline is only as good as its plan and its sensors. Document conditions and calibration, and be careful not to overstate what one indicator proves.
VerdictStrong when sampling covers occupied periods and results are reported by zone.
Watch forSingle-day studies, poorly placed sensors and uncalibrated readings.
Do nextPilot one floor, review the report format and then extend to the building.
Frequently asked questionsWhat Building Teams Ask About IAQ Baselines
How long should a baseline run?
Long enough to cover typical occupied days, quiet periods and weather changes. Many teams plan weeks rather than days.
Discuss a sampling period.
Is carbon dioxide enough on its own?
Can permanent sensors double as baseline sensors?
Who should receive the report?
What happens after the baseline?
Evidence before improvement
Set the Starting Line for Healthier Indoor Air
Book a session with iFactory AI to scope your baseline study, choose sensors and agree a reporting format that proves results over time.
