What this sector has to measure
Building services instrumentation is dominated by commissioning. A building is designed to deliver certain conditions, and the instruments exist during construction to demonstrate that it actually does - airflow at each terminal, water flow through each circuit, pressure relationships between spaces, and the temperatures the control system is trying to hold. Most of these measurements are made once, carefully, and then revisited only when the building fails to perform.
That gives the sector a distinctive feature: portability matters about as much as accuracy. The engineer commissioning a building moves between floors, plant rooms and rooftops, so the instruments are hand-held, battery powered and expected to survive being carried around a site. The same instruments are then used for troubleshooting and periodic verification, which is what keeps them relevant long after handover.
The second theme is that the quantities are small and frequently differential. Airflow is often a pressure difference across a terminal or a filter, humidity matters within a narrow band both for comfort and for condensation risk, and the water flow in a circuit may be a fraction of what a process plant would regard as a small flow. An instrument chosen on the basis of its range rather than its ability to resolve small differences frequently turns out to be unusable for the job it was bought for.
Where the instruments sit
Commissioning and handover
Airflow and water flow balancing, terminal and diffuser measurement, pressure relationships and control verification. Portability and repeatability matter more than the finest accuracy, because the result is usually a comparison between terminals rather than an absolute figure.
Plant rooms and hydraulics
Boilers, chillers, pumps, heat exchangers and distribution circuits. Flow, temperature, pressure and differential pressure across filters and valves, measured for setting up and for diagnosis.
Building control and indoor environment
Temperature, humidity, carbon dioxide and pressure in occupied spaces, feeding the control system and the ventilation strategy.
Energy and performance monitoring
Heating and cooling energy, electricity consumption and run hours, used to verify performance and to allocate cost between areas or tenants.
Instrumentation used in this sector
| Measurement | What is measured in this sector | Instruments commonly specified |
| Airflow and pressure | Air velocity and volume at terminals and in ducts, duct static pressure, and pressure relationships between spaces | Hot-wire and vane anemometers, capture hoods for terminal measurement, and differential-pressure instruments for filters, fans and room pressure relationships |
| Temperature and humidity | Supply, return and space temperature, surface temperature for condensation risk, and relative humidity indoors and outdoors | Portable and fixed temperature and humidity instruments, with sensors chosen so that the reading settles quickly enough to be usable on a walk-round |
| Hydronic flow and energy | Water flow in heating and cooling circuits, differential temperature across heat exchangers, and delivered thermal energy | Ultrasonic clamp-on meters where the pipe cannot be opened, electromagnetic meters in new installations, and thermal energy meters combining flow with a matched temperature pair |
| Pressure and differential | Filter and coil differential pressure, pump head and system pressure | Differential transmitters and portable manometers, with the range matched to the small differentials involved rather than to a general pressure range |
| Gas and indoor air | Carbon dioxide as a ventilation indicator, carbon monoxide from combustion, and refrigerant detection in plant rooms | Indoor air quality monitors, portable detectors for combustion checking, and fixed refrigerant detection in plant rooms and at chiller locations |
| Electrical and energy | Power and energy consumption of individual plant items and of the building as a whole | Power meters and energy meters, with the measurement class matched to what the figure is used for - a tenant charge or a maintenance trend |
Commissioning instruments are carried, so weight, battery life and a fast settling time are part of the requirement rather than conveniences.
How to specify for a building services installation
- Whether the instrument is for commissioning, for permanent installation, or for both. Commissioning instruments are portable and rugged, while installed instruments are judged on long-term stability instead.
- The differential being measured, because building services work involves very small pressure and temperature differences and an instrument with the wrong range cannot resolve them.
- Settling time and response, since an engineer measuring hundreds of terminals cannot afford to wait for a slow sensor at each one.
- Portability and battery life, which determine whether the instrument is actually carried and used rather than left behind.
- The duct or circuit where the measurement is made, including whether it can be opened, because clamp-on measurement avoids draining a system but accepts a lower accuracy in exchange.
- Whether the result is a comparison between points or an absolute figure, since relative measurement across a building is frequently the requirement and is more forgiving of absolute accuracy.
- The record required, including whether it has to be logged, reported, or handed to a commissioning authority in a defined format.
- The environment: dirty plant rooms, rooftops, occupied spaces and condensation risk, all of which affect the enclosure rather than the sensor.
Standards and approvals that may apply
- Commissioning and building performance requirements applied by the project, which define what has to be demonstrated and in what form.
- Indoor environmental quality requirements, which set the conditions the measurement has to verify rather than the instrument.
- Energy performance and metering requirements, which may prescribe the measurement class for figures used for reporting or billing.
- Ventilation and indoor air quality requirements, including the carbon dioxide or contaminant limits used to control the ventilation rate.
- We describe what an installation may have to meet. We do not claim that an approval is held for a product unless the certificate has been supplied to us, and where it has not, the product page says so.
Applications in this sector
