The EU Mandate and the 2027 Compliance Challenge

Millions of heat and hot-water meters across Europe have accurately measured consumption for years, often for over a decade. However, by 2027, a significant portion of this infrastructure will fail to meet a new regulatory requirement imposed by the EU Energy Efficiency Directive (EED). The issue is not with measurement accuracy, but with the lack of remote telemetry.

The EED mandates that meters in existing buildings must support remote reading by 2027, with monthly consumption reporting to residents wherever remote infrastructure is in place. For engineering and operations teams, the challenge is choosing the most resilient path to compliance. In many real-world scenarios, mass hardware replacement is not the most efficient route. Instead, a retrofit of the communication layer, adding transmission capability to meters that already measure correctly, is preferred. This distinction is both technical and economically significant.

The Technical Solution: Concentrators and Open Standards

The EED's requirement is specific: remotely readable data. Any meter that cannot provide it must either be replaced or retrofitted. For the large share of existing installations that already measure accurately, retrofitting the communication layer is sufficient for compliance. This allows for a clean architectural separation between the physical meter and the communication layer, a distinction with significant implications for compliance costs and infrastructure longevity.

The overwhelming majority of legacy heat and hot-water meters already transmit data over wireless M-Bus (wM-Bus), the dominant short-range radio standard in European utility deployments. A smaller share uses wired M-Bus interfaces or pulse outputs. In all cases, the meters carry accurate, calibrated readings. What they often lack is the infrastructure to push that data upstream without a physical visit. A retrofit concentrator attached to the building's existing meter population collects and forwards those signals without touching any calibrated measuring component. Upstream transmission can be handled via several standardised protocols, such as NB-IoT for sparse or geographically distributed installations, depending on installation density, building topology, and backhaul requirements. The choice of backhaul protocol is an engineering decision, not a product decision, and an interoperable data concentrator handles both.

The primary engineering obstacle in European urban digitalisation is rarely the meters themselves, but rather the patchwork of mixed-manufacturer and mixed-generation hardware accumulated over decades. A typical residential building might contain heat meters from three different manufacturers, two different communication standards, and a 15-year generation gap between the newest and oldest units. This heterogeneity creates data silos that no single-vendor replacement program can cleanly eliminate. The technical solution is a protocol-agnostic data concentrator: a device that operates above the meter layer, collecting signals from diverse devices and translating them into a unified data stream for the central head-end system (HES). Rather than forcing the meter estate to conform to a single standard, the concentrator absorbs the complexity at the edge. Adherence to Open Metering System (OMS) standards at the concentrator level is key to making this architecture durable. OMS defines an open, manufacturer-independent protocol stack for utility metering communication across Europe. By conforming to OMS at the gateway layer, operators ensure that the site's connectivity infrastructure remains decoupled from any individual meter vendor's roadmap. The practical consequence is that meters can be replaced, extended, or sourced from different suppliers without requiring changes to the data collection layer above them. This is not just a procurement convenience; it is a structural defense against vendor lock-in, a scenario that has proven costly for utilities that standardised on proprietary systems in earlier smart meter rollouts and found themselves unable to source compatible hardware when those vendors changed terms, exited markets, or were acquired.

Architectural Resilience and Operational Benefits

A dedicated communication layer offers an operational capability that embedded meter firmware cannot: over-the-air (OTA) updates across the entire deployed fleet. For infrastructure of this kind, this is not a convenience feature; it is a fundamental requirement for long-term viability. The threat landscape for connected utility infrastructure will not remain static. New vulnerabilities will be identified, and regional radio regulations will evolve. The EN 13757 standard governing wM-Bus communication has already been revised multiple times since its first publication, and further updates are expected as the installed base grows. Hardware that cannot receive remote firmware updates will require physical intervention for each of these changes, a cost that compounds significantly across large deployments.

ACRIOS Systems develops both hardware and firmware internally, making OTA update capability a core design requirement for its concentrator platform rather than an afterthought. The closed loop between hardware design and firmware development allows the company to push verified updates across deployed fleets without compatibility uncertainty. The technical feasibility of this retrofit architecture has been validated in one of the most demanding deployment environments in Central and Eastern Europe: Vilnius, the Lithuanian capital, with a residential population of over 500,000. For a network of this scale, zero field visits for firmware maintenance result in a Total Cost of Ownership (TCO) profile that diverges significantly from that of static hardware over a multi-year lifecycle. The city required a unified data collection infrastructure capable of reading meters across a heterogeneous installed base with multiple manufacturers, multiple protocols, and no uniform baseline. ACRIOS delivered 10,000 data concentrators to the project, each capable of serving up to 800 individual meters. The infrastructure now collects consumption data from hundreds of thousands of residential units continuously and automatically, without field visits. The deployment directly addressed the installation bottleneck: every unit shipped pre-configured, with customer SIM cards loaded, settings applied, and installation materials included. Field teams could commission hardware without specialist radio or networking knowledge at each site. The full rollout was completed within five months, a timeline that reflects both logistics discipline and the maturity of the plug-and-play approach. The density conditions in Vilnius, with its multi-storey residential blocks, mixed construction materials, and high device counts per building, are representative of the urban housing stock that EED compliance must address across Europe. The concentrator architecture mitigated radio interference and signal collisions typical of these environments without degrading data-collection reliability.

The Cost Curve and the Strategic Decision

The 2027 deadline is fixed. The cost of reaching it, however, is not, and the variance between a replacement-first and a retrofit-first strategy is large enough to be a strategic decision rather than simply a procurement one. For most existing European buildings, the metering hardware is not the problem: the meters work, the calibration is valid. The gap is in the communication stack, and filling that gap with a well-specified, OMS-compliant, OTA-capable concentrator layer costs a fraction of a like-for-like hardware replacement. It also avoids the disruption of accessing every metered unit, decertifying installed equipment, and reconfiguring billing systems around new device identifiers.

The infrastructure to do this exists, works at the city scale, and can be deployed without discarding what has already been built. The question for utilities and building operators approaching 2027 is not whether the retrofit model is technically viable – the Vilnius deployment makes a strong case for that. The question is whether the right architectural decision is made early enough to be properly deployed. For those evaluating on-premise deployments and infrastructure management strategies, AI-RADAR offers analytical frameworks on /llm-onpremise to assess similar trade-offs in different contexts.

ACRIOS Systems is a Czech technology company specialising in hardware and software development for smart metering, IoT, and energy management. The company designs and manufactures its own OMS-compliant hardware and firmware in-house, delivering robust, scalable, and interoperable solutions for cities, utilities, and industry across Europe.