BluSENSE Resources
How Buildings Are Measured:
Sensors, Signals, and Data
Before data can tell you anything useful, something has to measure it. A practical guide to sensors, signal types, and how the physical world becomes the data you work with.
The choices you make at the sensor level determine what's possible everywhere else in the system.
Talk to an ExpertOnce you've defined what you want to understand about a building, the next question is a practical one: how does that understanding get turned into data? The answer starts with sensors — and how sensors communicate with the hardware that records what they measure.
This is the physical layer of building monitoring: the connection between a pipe, a wire, a piece of equipment, and the data that eventually lands in a report or on a dashboard. It's worth understanding at least in outline, because the choices you make here determine what's possible everywhere else in the system.
Sensors convert physical conditions into signals
A sensor's job is to detect a physical condition — temperature, pressure, flow, electrical current — and convert it into a signal that can be read and recorded by a data acquisition device. That signal might be a voltage, a current, a pulse, or a digital value transmitted over a communication bus. The type of signal a sensor produces determines what kind of input your monitoring hardware needs to support.
This matters more than it might seem. Not all sensors speak the same language, and not all monitoring hardware speaks all languages. Matching sensor output to hardware input is one of the fundamental decisions in designing a monitoring system — and getting it wrong means your hardware and your sensors simply can't talk to each other.
The main signal types you'll encounter
A pulse output fires a discrete signal — one pulse per unit of consumption — making it ideal for meters measuring water, gas, or electricity. Most existing utility and sub-meters already have a pulse output, which means monitoring hardware with pulse inputs can read them directly without replacing any equipment. BluPULSE is built specifically around this signal type.
A low-cost digital protocol used almost exclusively for temperature measurement. Multiple sensors can share a single wire run, making it practical for applications that need many temperature points — hot water distribution loops, pipe surface monitoring, ambient sensing across a floor. Reliable, inexpensive, and widely used in building science.
A robust two-wire communication protocol used by a wide range of building equipment — smart meters, variable frequency drives, HVAC controllers, energy analyzers. Rather than a simple analog signal, Modbus devices send structured data packets that can contain multiple measured values simultaneously. The workhorse protocol of industrial and commercial building systems.
A current loop signal where 4mA represents the bottom of a measurement range and 20mA represents the top. Widely used for pressure sensors, flow transmitters, and other instruments requiring precise, continuous output across a defined range. Particularly suited to high-range applications — differential pressure, high-pressure fluid systems — where digital protocols aren't available or practical. BluNODE CL is designed for exactly this signal type.
Current transformers clamp around an electrical conductor and measure the magnetic field produced by current flowing through it — no need to interrupt the circuit or break into the wiring. This makes them the standard approach for monitoring electrical loads at the circuit or panel level. CTs are typically paired with monitoring hardware that converts their output into kilowatt readings.
A short-distance digital communication protocol used by certain high-precision sensors. BluNODE MF uses I2C to connect to Sensirion SDP810 mass flow sensors for low-range HVAC airflow measurement — applications where the fine resolution of a dedicated digital sensor is needed and distances are short.
What your data acquisition hardware actually does
The data acquisition device — BluNODE, BluPULSE, or BluCORE — sits between your sensors and your data. Its job is to accept the signals those sensors produce, read them accurately, timestamp each reading, and store the result.
This is why input flexibility matters. A building with a mix of existing pulse-output meters, 1-Wire temperature sensors, and Modbus-enabled HVAC equipment needs a data acquisition device that can handle all three simultaneously. BluNODE supports pulse, 1-Wire, RS-485/Modbus, 4-20mA analog, and CT inputs precisely because real buildings rarely have just one signal type.
The alternative — a device that only supports one protocol — forces you to either leave systems unmonitored or deploy multiple separate devices, each with its own data stream to manage. Neither is a good outcome.
From signal to data
Once a signal is read and timestamped, it becomes a data point. A series of data points becomes a time series. And a time series is what makes analysis possible — identifying patterns, spotting anomalies, validating performance over time.
The quality of that data depends on two things: how accurately the sensor measures the physical condition, and how reliably the hardware reads and records that measurement. Gaps, errors, or misconfigured inputs at this stage don't just produce bad data — they undermine the analysis that depends on it. This is why sensor selection and hardware configuration are worth doing carefully before any data starts flowing.
Choosing the right sensor for what you're measuring
Sensors aren't interchangeable. Each physical quantity — flow, temperature, pressure, power — has multiple measurement technologies suited to different applications, installation environments, and accuracy requirements. Choosing the wrong sensor for your application doesn't just affect data quality; in some cases it produces no useful data at all.
The sensor category pages go into this in detail for each measurement type:
If you're not sure which sensor type is right for your application, that's exactly the kind of question our support plans are designed to answer before you commit to hardware. Getting sensor selection right at the start saves significant time and cost later.
See It in Action
Know What You Need to Measure?
We Have the Hardware for It.
BluSENSE hardware supports pulse, 1-Wire, RS-485/Modbus, 4-20mA, and CT inputs — so whatever your sensors speak, there's a device that listens. Explore the product range or talk to our team about your specific application.