Sensio Air for HVAC

One sensor at the return reads the whole room.

Every ventilated room sends its air back out through a return vent: the breath, the pollen, the dust and the vapours, all on their way to the air handler. Sensio Air is a small optical sensor that sits just inside that vent. It reads the room’s air as it leaves, and gives the building system a live reading to ventilate by.

Book a call with our team See both ways to fit it

Ø70 × 36 mm · Wi-Fi · BACnet/IP and API · 17 granted patents

Read at the return

What it reads in the air leaving each room

CO₂Climbs as a room fills. The clearest sign a zone needs more outdoor air.

VOCsVapours from cleaning products, disinfectants, paint and new fit-outs.

MoldSpores identified as they appear, down to the species.

PollenGrass, tree and weed pollen carried in through doors, windows and the outdoor air intake.

Dust mitesFragments in the air, a common trigger for allergies and asthma.

Pet danderCarried in on clothes and bags, and left behind in rooms.

TemperatureComfort, and an early sign that heating or cooling is struggling.

HumidityToo damp and mold grows. Too dry and eyes and throats complain.

Why the return

On a desk, a sensor reads its corner. At the return, it reads the room.

The air in a room is never the same everywhere. A sensor on a desk or a shelf reads the air around it, and misses the person breathing on the other side of the table. The return vent is where all of the room’s air ends up, mixed, on its way back to the air handler. A sensor there reads what the whole room is breathing.

The whole room: Everything the ventilation draws out of the room goes past the sensor.
Out of the way: Nobody moves it, covers it or knocks it off a shelf.
One per return: One sensor for each room or zone with a return of its own.
The same readings: The same eight measures, dashboard and alerts as a sensor in the room.

Where the reading comes fromDiagram

On a deskThe air around the desk.

At the returnThe air of the whole room.

A diagram, not to scale. On a desk the sensor reads the air near it. At the return it reads the air the whole room sends back to the air handler.

Two ways to fit it

In the duct, or behind the grille. Both read the same air.

Sensio goes where the room’s air leaves it. Choose the fitting that suits the building: inside the return duct, as in the film above, or on the back of the grille itself.

Design A · as in the film

In the return duct

On a steel bracket on the duct wall, just behind the grille. The air passes across its face on the way to the air handler.

Fitting: A corrosion-resistant L-shaped bracket inside the duct. Power comes in through a sealed grommet in the duct wall, from low-voltage wiring or a PoE adapter.
Access: A removable access panel in the duct, for cleaning.
Suits: New fit-outs and refurbishments, and anywhere the duct is easy to reach.

Design B

Behind the return grille

On the back of the grille, behind its blades, facing the room. The room’s air passes it on the way into the duct.

Fitting: The grille comes off, the sensor goes on its back, the grille goes back on. Nothing is cut into the duct; the cable runs to the nearest power.
Access: Take the grille off to reach it.
Suits: Existing buildings and quick retrofits, and anywhere the duct is hard to reach.

Both designs use the same Sensio Air sensor and read the same eight measures. We help you choose between them and plan the installation.

The gate

See what gets past the filter.

Outdoor air comes into the building through an intake, and it brings its own pollen and pollution. The filter at that gate between outdoors and indoors is there to stop most of it. Put one Sensio on the outdoor side of the filter and one on the indoor side, and the dashboard shows how much it stops, hour by hour.

Two sensors: One upstream of the filter and one downstream, side by side on the same dashboard.
A gap that closes: When the indoor side starts to follow the outdoor side, air is getting past: a gap around the filter, a torn panel or a bypass.
Pollen season: The outdoor side climbs on high-pollen days while the indoor side stays low.
Outdoors and in: Or put one sensor outside under shelter and one by the fresh-air intake, to see the difference the whole building makes.

Pollen on each side of the filterOne day

Outdoor sideIndoor side

An illustration, not measured data. Pollen outdoors peaks in the morning and again in the evening. On the indoor side of the filter it stays low all day.

Building automation

Outdoor air when a room needs it, from the reading at its return.

Sensio speaks BACnet/IP and has an open API, so its readings go straight into the building management system you already have. When CO₂ climbs at a zone’s return, the system brings in more outdoor air for that zone, and turns it back down when the air clears.

BACnet/IP: Mapped into your building system by our team.
Cloud API: For your own tools, dashboards and reports.
Rules you set: Limits per zone, and who hears about what: people, the building, or both.

What happens when a zone fills upExample

Zone 3 returnCO₂ 1,120 ppmOver the limit you set

SensioFlags the zoneWithin minutes

Building systemGets the readingOver BACnet/IP

Outdoor airZone 3 opens upOnly that zone

A little later: 640 ppm at the return, and the outdoor air turns back down.

Example readings. The loop runs without anyone watching it.

Maintenance

Service the system by what the air says, not by the calendar.

The air leaving each room says how the plant behind it is doing. A filter that lets pollen through, a coil or drain pan that keeps a return damp while mold spores appear, a zone that never quite reaches temperature: each one shows up in the readings before it turns into a complaint.

Filters: Checked against both sides of the filter, not only the date on the label.
Damp and mold: Humidity that stays high at a return while mold spores start to appear points to a leak, a coil or a drain pan.
Comfort: Temperature drift by zone shows heating or cooling falling behind.
The sensor itself: Factory-calibrated. No samples, no reagents, nothing to refill. Reach it through the access panel or the grille.

To check todayExample

AHU 1
Check the filter sealIndoor side following the outdoor side since Tuesday.
Check
Zone 4
Inspect the coil and drain panHumidity high at the return for three days, mold spores rising.
Check
Zone 2
Check the fan coilSlow to cool each afternoon.
Check
The rest
Nothing to doAll readings in range.
Clear

An example of the daily list. Three places need someone; the rest do not.

Electricity

Bring in outdoor air for the people in the room, not for the clock.

Most systems bring in outdoor air on a timetable: every zone, the same hours, whether a room holds forty people or none. All of that air has to be heated or cooled. With a live reading at each return, the outdoor air can follow the people instead.

On demand: Outdoor air tied to the CO₂ at each zone’s return instead of a fixed schedule.
Empty zones: CO₂ settling back to outdoor levels shows a zone has emptied, so the plant can ease off.
Proof: Before and after, in your own readings, zone by zone.

What this saves depends on your building and how it runs today. We work it out with you from your own data.

When each zone gets outdoor airOne day

On a timetableEvery zone, the same hours

All zones

On demandEach zone, when its people are there

Lobby

Offices

Meetings

Canteen

00:0006:0012:0018:0024:00

An illustration, not measured data. A deeper blue means more outdoor air. On demand, each zone’s outdoor air follows the people in it.

Also Commercial buildings A shop, a clinic, offices and hotel floors, each with its own air. Also Schools and classrooms Classrooms have a page, and a film, of their own.

Want to learn more?

Book a call with our team. Tell us how your building is ventilated and we will show you where Sensio would go, return by return.

Book a call with our team See plans