Wireless sensors solve the biggest challenge in BAS retrofits: running new wires in occupied buildings. Whether upgrading a historic building, adding zones to an existing system, or deploying IoT monitoring, wireless sensors reduce installation cost by 40-70% compared to wired alternatives while minimizing disruption to occupants.
| Factor | Wired | Wireless | Advantage |
|---|---|---|---|
| Installation Cost | $150-400 per point | $50-200 per point | 40-70% savings |
| Installation Time | 2-4 hours per point | 15-30 min per point | 75% faster |
| Building Disruption | Ceiling/wall access, patching | Sensor mount only | Minimal |
| Historic Buildings | May violate codes | Non-invasive | Often only option |
| Flexibility | Fixed location | Relocatable | Better for reconfigurations |
| Technology | Frequency | Range (indoor) | Power Source | Topology | Best For |
|---|---|---|---|---|---|
| EnOcean | 902 MHz (US) / 868 MHz (EU) | 30-100m | Energy harvesting (no battery) | Star | BAS sensors, switches |
| Zigbee | 2.4 GHz | 10-30m | Battery (2-5 years) | Mesh | Lighting, occupancy |
| Z-Wave | 908 MHz (US) | 30-50m | Battery (2-5 years) | Mesh | Residential/light commercial |
| Bluetooth LE (BLE) | 2.4 GHz | 10-30m | Battery (1-3 years) | Star/Mesh | Beacons, asset tracking |
| LoRaWAN | Sub-GHz (915 MHz US) | 500m-2km indoor | Battery (5-10 years) | Star | Campus, industrial |
| Wi-Fi (HaLow) | 900 MHz | 100-300m | Battery (2-5 years) or powered | Star | High bandwidth, IP native |
EnOcean is the most popular wireless technology for commercial BAS because sensors require no batteries - they harvest energy from light, temperature differences, or motion.
| Energy Source | Sensor Type | Minimum Requirement |
|---|---|---|
| Solar/Indoor Light | Temp, humidity, occupancy | 200 lux (typical office) |
| Thermal (Peltier) | Pipe/surface temperature | 2C temperature differential |
| Kinetic (Piezo) | Switches, window contacts | Single press generates enough energy |
| Sensor | Measures | Harvesting | Accuracy | Update Interval |
|---|---|---|---|---|
| Room Temp/Humidity | Temperature + RH | Solar | +/- 0.3C, +/- 2% RH | 10-30 min |
| Occupancy/Motion | PIR detection | Solar | 5m range, 90 degree cone | Event-based |
| CO2 Sensor | CO2 concentration | Solar + supercap | +/- 50 ppm | 10-15 min |
| Light Level | Illuminance (lux) | Solar | +/- 10% | 5-15 min |
| Window/Door Contact | Open/closed | Kinetic (magnet) | Binary | Event-based |
| Pipe Temperature | Surface temperature | Thermal | +/- 0.5C | 15-30 min |
| Water Leak | Presence of water | Solar + probe | Binary | Event-based |
| Gateway | Input Protocol | Output Protocol | Max Sensors | BAS Integration |
|---|---|---|---|---|
| EnOcean to BACnet/IP | EnOcean | BACnet/IP | 128 per gateway | Direct BACnet client |
| EnOcean to Modbus | EnOcean | Modbus TCP/RTU | 64 per gateway | Via Niagara/Metasys driver |
| Zigbee Coordinator | Zigbee | REST API / MQTT | 200+ per coordinator | Via integration module |
| LoRaWAN Network Server | LoRaWAN | MQTT / REST | 1000+ per server | Via MQTT bridge |
| Multi-Protocol Gateway | Multiple | BACnet/IP | 256 per gateway | Direct BACnet |
Gateway Settings:
IP Address: 192.168.1.100 (static)
BACnet Device Instance: 1500001
BACnet Port: 47808
EnOcean Radio Settings:
Frequency: 902 MHz (US)
Learn Mode: Auto-detect new sensors
Encryption: AES-128 (recommended)
Sensor Mapping:
Sensor ID: 04A3B2C1 -> BACnet AI:1 (Room Temp Zone 101)
Sensor ID: 04A3B2C2 -> BACnet AI:2 (Room Humidity Zone 101)
Sensor ID: 04A3B2C3 -> BACnet BI:1 (Occupancy Zone 101)
Most common wireless BAS sensor. Place at 4-5 feet height on interior wall, away from direct sunlight and HVAC diffusers.
Specifications:
Passive infrared detects human movement. Mount on ceiling (2.4-3m height) for best coverage.
Specifications:
Critical for demand controlled ventilation (DCV). Place at breathing zone height (4-5 feet).
Specifications:
For daylight harvesting and lighting control. Mount near window or in zone to be controlled.
Kinetic energy harvesting - no battery. Magnet and sensor pair. Reports open/closed state on each state change.
Clamp-on temperature sensor using thermal energy harvesting. Requires minimum 2C differential between pipe and ambient air.
| Material | Signal Loss | Impact |
|---|---|---|
| Open air | Minimal | Full range |
| Drywall/wood | 3-5 dB | Minor reduction |
| Glass | 2-4 dB | Minor reduction |
| Concrete block | 10-15 dB | Significant reduction |
| Reinforced concrete | 15-25 dB | Major reduction |
| Metal/foil | 20-30+ dB | Severe - may block completely |
| Elevator shaft | 30+ dB | Typically blocked |
| Building Type | Gateway Coverage | Sensors per Gateway |
|---|---|---|
| Open office | 50-80m radius | 50-80 sensors |
| Partitioned office | 30-50m radius | 30-50 sensors |
| Concrete/steel building | 15-30m radius | 15-30 sensors |
| Multi-floor (per floor) | 1 gateway per floor | Varies by construction |
No batteries to replace. Maintenance: annual visual inspection, clean solar cell if dusty. Expected life: 10-15 years (limited by electronics, not power).
| Technology | Typical Battery | Expected Life | Replacement Cost |
|---|---|---|---|
| Zigbee | CR2032 or AA | 2-5 years | $2-5 per sensor |
| Z-Wave | CR123A | 2-5 years | $3-8 per sensor |
| BLE | CR2032 | 1-3 years | $2-5 per sensor |
| LoRaWAN | AA or C cell | 5-10 years | $2-5 per sensor |
Most wireless sensors report battery level to gateway. Configure BAS alarm when battery drops below 20%. Schedule batch replacements during planned maintenance windows.
| Risk | Description | Mitigation |
|---|---|---|
| Eavesdropping | Intercepting sensor data | AES-128 encryption on all sensors |
| Replay Attack | Retransmitting old sensor data | Rolling code or sequence numbers |
| Jamming | Flooding RF frequency | Frequency hopping, detect signal loss |
| Rogue Devices | Unauthorized sensors joining network | Whitelist mode on gateway |
| Gateway Compromise | Attacker gains access to gateway | Network segmentation, strong passwords |
| Item | Quantity | Unit Cost | Total |
|---|---|---|---|
| EnOcean room sensors (temp/humidity) | 60 | $80 | $4,800 |
| EnOcean occupancy sensors | 20 | $120 | $2,400 |
| EnOcean CO2 sensors | 10 | $250 | $2,500 |
| EnOcean contact sensors | 10 | $45 | $450 |
| BACnet gateways | 3 | $800 | $2,400 |
| Installation labor | 100 points | $30/point | $3,000 |
| Commissioning | 1 week | $2,000 | $2,000 |
| Total | $17,550 |
Comparison: Equivalent wired installation would cost $35,000-50,000 (labor-intensive wire pulls in occupied space).
Wireless sensors are the practical choice for BAS retrofits. EnOcean energy harvesting eliminates battery maintenance. Proper site surveys and gateway placement ensure reliable coverage. BACnet gateway integration provides seamless connection to existing Niagara, Metasys, or Desigo platforms.
Key steps: survey first, select technology based on building construction and requirements, install gateways before sensors, perform thorough commissioning with 24-hour burn-in, and document everything.