Smart energy sensors: metering per use, so you can act
A sensor on its own saves nothing. What saves is the chain that links a reading to a setting — and that chain starts with metering split by use rather than one main meter.
What there is to measure
Three families, and the second is the one most often skipped.
Consumption
Electricity, gas, water, heat. One meter or sub-meter per use, read at a fine enough interval that drift shows up before the invoice does.
The quantities that drive consumption
Temperature, humidity, CO₂, occupancy, window or door opening. These are what explain a consumption figure: without them, a curve does not say why it is rising.
Equipment state
Running or stopped, applied setpoint, reported fault. Equipment running outside occupancy hours is the most common source of savings, and the easiest to establish.
Why per-use metering changes everything
A main meter gives a total. It lets you observe that consumption is rising; it does not say which equipment is responsible. Until consumption is separated per use — heating, ventilation, cooling, lighting, process — every action remains a hypothesis, and no saving can be proven.
This is also why an inventory comes first: many installed meters already have a pulse output or a usable bus, and get instrumented rather than replaced.
How a reading gets back
On the field side, meters speak Modbus or M-Bus, and building management speaks BACnet or KNX. On the link side, the choice follows the installation: LTE-M for most cellular devices, NB-IoT for fixed meters in basements, LoRaWAN for a dense fleet on a single site.
Where the processing sits is a separate decision, covered in our article on where embedded intelligence belongs.
From reading to setting
Measuring without adjusting produces curves, not savings. What produces savings is detecting a setpoint drift, equipment running outside occupancy hours, or a gap between expected and actual consumption — and then correcting it. Supervision that only displays is supervision that costs.
What the regulation requires
For non-residential buildings, the recast EPBD directive turns building automation from good practice into a deadline, with thresholds based on installed power. The obligations, the Smart Readiness Indicator and where a multi-building portfolio should start are detailed in our article on the EU buildings directive.
Frequently asked questions
What is a smart energy sensor?
A smart energy sensor measures a consumption — electricity, gas, water, heat — or a quantity that drives it, such as temperature, occupancy or opening, and sends that reading to a supervision layer able to turn it into an action. The intelligence is not in the sensor alone: it is in the chain that links the reading to a setting.
Which sensors are needed to track a building's energy performance?
At minimum, metering per use — heating, ventilation, cooling, lighting, process — rather than a single main meter, plus temperature, humidity and occupancy probes in the controlled zones. Without reliable per-use metering you know neither where to act nor how to demonstrate a gain.
Is a single main meter not enough?
It gives a total, so it lets you observe drift but not attribute it. Until consumption is separated per use, any action remains a hypothesis: you can neither target the equipment at fault nor prove that a setting change produced the expected saving.
Which protocols are used to collect energy readings?
On the field side you mostly meet Modbus and M-Bus for meters, BACnet and KNX for building management. On the link side, LTE-M suits most cellular devices, NB-IoT suits fixed meters in basements, LoRaWAN suits a dense fleet on one site. The choice follows installation constraints, not preference.
Is a wireless sensor reliable for metering?
For monitoring purposes, yes, provided you accept a sampling interval rather than a guaranteed instantaneous reading. For metering that underpins billing or cost allocation, what matters is the meter's metrology, not the radio link — and that falls under its own requirements, to be checked case by case.
How does a sensor become a real saving?
When the reading triggers a setting change. Measuring without adjusting only produces curves: the saving comes from spotting a setpoint drift, equipment running outside occupancy, or a gap between expected and actual consumption — and then correcting it.
Do existing meters have to be replaced?
Not always. Many installed meters already offer a pulse output or a usable bus: they get instrumented rather than replaced. An inventory of what is in place therefore always precedes the choice of hardware.
A portfolio to instrument?
Describe your context: we start with an inventory of what can already be measured.