The recast EPBD makes Building Automation and Control Systems mandatory for much of Europe's commercial property — but the directive describes what a system must do, not how to build one. This guide closes that gap. It lays out a complete, layer-by-layer LoRaWAN® reference architecture you can adapt to almost any non-residential building to deliver continuous monitoring, demand-based control and the data trail a BACS requires.
If you need the regulatory background first, start with The EPBD Is Now Law: What the 2026 BACS Mandate Means for Your Building. Here, we assume the obligation and focus on the design.
Design Goals: What the Architecture Must Deliver
A compliant system has to continuously monitor, log and analyse energy use; benchmark efficiency and flag faults; control technical building systems; and be interoperable across vendors. The European standard that quantifies this is EN ISO 52120-1:2022 (which replaced EN 15232), grading automation from Class D up to Class A — the high-performance tier the EPBD effectively pushes new and renovated buildings toward.
The Three-Layer Reference Architecture
Every LoRaWAN building deployment resolves into three layers. Get the boundaries right and the system scales cleanly from a single floor to an entire estate.
Layer 1 - Sensing
Battery-powered sensors and meters report on a schedule or when a threshold is crossed. Because LoRaWAN devices last 5–10+ years on a battery and mount without cabling, you can instrument a building room-by-room without disrupting occupants — the decisive advantage when retrofitting existing stock.
Layer 2 - Connectivity
One or more LoRaWAN gateways receive every uplink and forward it to a network server. Sub-GHz 868 MHz penetrates floors and walls, so a single indoor gateway typically covers a whole building and backhauls hundreds of devices; larger or multi-storey sites add a second for resilience. Gateways such as the Milesight UG65/UG67 can run an embedded network server and bridge directly to building systems.
Layer 3 - Application
The network server decrypts and decodes uplinks, then feeds them to the systems that act on the data: a BMS, an analytics dashboard, or both. This is where logging, benchmarking, alerting and control actually happen — the functional core of BACS compliance.
A Zone-by-Zone Sensor Plan
Rather than scatter sensors at random, instrument the building by zone. This keeps device counts efficient and maps directly onto the control loops below.
| Zone | What to monitor | Device category |
|---|---|---|
| Open offices & workspaces | Occupancy, CO2, temperature, humidity | People counters + air-quality sensors |
| Meeting & focus rooms | Occupancy, CO2 | Occupancy sensors + CO2 sensors |
| Corridors & common areas | Presence, ambient conditions, light | PIR & ambience sensors |
| Restrooms | Occupancy, air quality / odour | Occupancy + air-quality sensors |
| Plant room (HVAC) | Flow/return temperatures, runtime, pressure | Temperature & pressure sensors |
| Electrical room / distribution boards | Per-circuit electricity use | LoRaWAN energy meters + current transformers |
| Radiators & fan coils | Zone temperature & setpoint control | Smart TRVs & HVAC thermostats |
Zone-by-zone plan
Instrument the building zone by zone
Map every space to what it should sense. It keeps device counts lean, mirrors how the building is actually used, and feeds the control loops directly.
The Two Control Loops That Save the Most
Monitoring alone satisfies the letter of BACS; control is where the savings — and the payback — come from. Two loops deliver the bulk of the benefit.
1. Demand-controlled ventilation (DCV)
CO2 sensors in occupied zones drive ventilation rates in proportion to actual occupancy instead of running fans on a fixed schedule. When a meeting room empties, CO2 falls and airflow throttles back; when it fills, ventilation ramps up to keep air healthy. This is the high-performance function EN ISO 52120-1:2022 specifically rewards, and it routinely removes the single largest chunk of HVAC energy waste.
2. Occupancy-based HVAC & lighting setback
Occupancy and people-counting data lets the BMS set back heating, cooling and lighting in unused spaces and restore comfort just before people return. Tied to smart TRVs or fan-coil thermostats, it turns real occupancy — not assumptions — into the control signal.
Sub-Metering: The Backbone of Continuous Energy Monitoring
"Continuously monitoring and benchmarking" energy use is impossible from a single utility meter. Circuit-level sub-metering — LoRaWAN energy meters with split-core current transformers on major loads (HVAC, lighting, lifts, IT, EV charging) — gives you the granular, time-stamped data that both drives optimisation and proves compliance. Clamp-on CTs install without breaking the circuit, so existing boards can be metered live.
Integration: Getting Data Into the BMS
The application layer is where interoperability — an explicit BACS requirement — is won or lost. A LoRaWAN network server can hand data to building systems through several standard pathways:
- BACnet/IP or Modbus TCP — the native languages of most BMS platforms; many industrial LoRaWAN gateways bridge directly.
- MQTT — lightweight publish/subscribe to an IoT platform, broker or cloud dashboard.
- REST / HTTP API — direct integration with analytics platforms and frameworks such as Niagara.
Whichever path you choose, the application layer must retain time-series logs. Those logs are what demonstrate continuous monitoring to an auditor — keep them, don't just stream them. For network design, frequencies and scaling, see our Ultimate Guide to LoRaWAN Deployment in Europe.
Sizing and Phased Rollout
Resist the urge to deploy everything at once. A phased rollout de-risks the project and delivers data — and savings — faster.
- Survey first. Confirm gateway coverage with a quick site survey and a field tester before fixing sensor locations.
- Pilot one floor or wing. Prove the data flow end-to-end into the BMS, including logging and alerting.
- Prioritise battery life over density. A sparse, low-maintenance network beats a dense one that needs constant attention.
- Scale by zone. Replicate the proven pattern across the building, adding a second gateway only where coverage or resilience demands it.
Example Bill of Materials
A representative set of building blocks, mapped to layer. Exact models depend on building size and existing systems — our team can tailor the list.
| Layer / function | Example devices |
|---|---|
| Sensing — air quality / CO2 | Milesight AM103 / AM307 indoor air-quality sensors |
| Sensing — occupancy | Milesight VS121 / VS350 people counters; WS202 PIR |
| Sensing — energy sub-metering | Eastron SDM630MCT-LoRa meter + PowerUC split-core CTs |
| Sensing — HVAC control | Milesight WT101 / WT201 smart thermostats & TRVs |
| Sensing — plant monitoring | Milesight TS101 temperature probe; EM500-PP pressure sensor |
| Connectivity | Milesight UG65 / UG67 LoRaWAN gateways (embedded LNS + BMS bridge) |
| Application | Network server → BMS via BACnet/Modbus/MQTT/REST + dashboard |
Frequently Asked Questions
Common design questions from integrators and facility teams planning a BACS-ready LoRaWAN build.
How many gateways does one building need?
Most buildings are covered by a single indoor gateway thanks to sub-GHz penetration, with one gateway backhauling hundreds of devices. Large footprints, basements, or multi-storey concrete structures may need a second gateway for coverage and resilience — confirm with a site survey before finalising.
Does LoRaWAN integrate with my existing BMS?
Yes. A LoRaWAN network server can deliver data to a BMS over BACnet/IP, Modbus TCP, MQTT or a REST API. Many industrial gateways bridge these protocols directly, so sensor data appears in the BMS alongside existing points without bespoke middleware.
Can I sub-meter without shutting down the electrical board?
Split-core current transformers clip around a conductor without breaking the circuit, so major loads can be metered with minimal downtime. Final connection should always be carried out by a qualified electrician in line with local regulations.
What is EN ISO 52120-1 and how does it relate to the EPBD?
EN ISO 52120-1:2022 is the European standard (replacing EN 15232) that classifies the energy-saving impact of building automation from Class D to Class A. It's the practical yardstick for the high-performance BACS functions the EPBD promotes, including demand-controlled ventilation.
Where should a phased deployment start?
Pilot one floor or wing with the full stack — sensing, gateway and BMS integration — and meter only the largest electrical loads first. Once the data flow and logging are proven, replicate the pattern zone by zone across the building.
Conclusion: One Architecture, Many Buildings
The same three-layer pattern — wireless sensing, gateway backhaul, and a BMS/analytics application layer — adapts to offices, schools, hotels, retail and healthcare alike. Designed around zones and the two high-value control loops, it satisfies the functional requirements of BACS, targets EN ISO 52120-1 Class A performance, and keeps the door open to scale. Build it once, prove it on a pilot, and replicate with confidence.
Designing a BACS-Ready Building?
Send us your floor plans or load schedule and our engineering team will scope the sensing layer, size the gateways and map the BMS integration — pre-configured and ready to ship.