Do wireless BAS sensors need any wiring at all?

The sensors themselves don't, but the network they join does. Zigbee, Thread, LoRaWAN, and EnOcean sensors all report back to a gateway or coordinator device, and that gateway is normally hardwired into the BAS network (Ethernet or a BACnet MS/TP trunk) so its data reaches the DDC panel or supervisory controller. A wireless deployment reduces the wiring from one run per sensor to one run per gateway, it doesn't eliminate wiring entirely.

How long do wireless BAS sensor batteries actually last?

It depends heavily on report frequency and the protocol's power profile — commonly 3 to 7 years for a coin-cell temperature or occupancy sensor reporting every few minutes, shorter for sensors that report more frequently or that also drive a display. Energy-harvesting protocols like EnOcean have no battery to track at all, since the device generates its own power from light, a temperature gradient, or the mechanical energy of an actuation.

What causes RF dead zones in a wireless BAS mesh?

Concrete and masonry walls, elevator shafts, dense metal equipment racks, and even large HVAC ductwork can attenuate or block RF signal between nodes. A well-designed mesh network mitigates this with self-healing routing — if a direct hop is blocked, traffic automatically reroutes through a neighboring node — but a site survey before installation is still standard practice to identify likely dead zones and place gateways or repeater nodes accordingly.

Is hardwired always the right choice for critical control points?

Not automatically, but it is the more common choice for points feeding a tight closed control loop where update latency and guaranteed delivery matter most, such as the space sensor driving a VAV box's primary control loop. Wireless has closed much of that gap for many use cases, but a hardwired point never has to compete for radio spectrum, never has a battery that can die mid-cycle, and reports at whatever rate the panel polls rather than a report interval chosen to conserve battery life.

Can hardwired and wireless sensors coexist on the same BAS?

Yes, and mixed deployments are common — a building might hardwire high-density, easily accessible new-construction areas while using wireless sensors for a historic wing, a temporary pilot program, or hard-to-reach points like a rooftop or a space where opening finished ceilings isn't practical. Both integrate into the same BACnet-based supervisory layer once the wireless gateway is on the network, so the choice can be made point-by-point rather than building-wide.

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Concept Explainer · Smart Buildings

Hardwired vs. Wireless BAS Sensors

Two ways to get a temperature reading from a room back to a DDC panel — and why the real trade-off isn't "which one is cheaper," it's where the cost and the failure risk end up living over the sensor's 10-15 year life.

Every BAS point needs two things: power, and a path back to a controller. A hardwired sensor gets both from the same dedicated cable — a home-run pair pulled through conduit or fished through a ceiling cavity straight to a DDC panel. A wireless sensor gets its path from a radio protocol like Zigbee, LoRaWAN, or EnOcean instead of a cable, but it still has to solve the power problem — usually with a battery, occasionally by harvesting energy from light or a temperature differential. Neither approach removes the underlying requirement; each just moves it somewhere else. Where it gets moved determines the entire cost, install time, and maintenance profile of the point.