Remote metre reading by 2027: Retrofit beats replacement

Across Europe, millions of heat and hot-water metres accurately measure consumption every day. Many have been in the field for a decade or more, performing their metrological function with high reliability. By 2027, a significant portion of this infrastructure will fail to meet a new regulatory requirement. Not because the sensing is wrong, but because the telemetry is missing.

The EU Energy Efficiency Directive (EED) mandates that heat and hot-water metres 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 most real-world deployments, that path is not mass hardware replacement. It is a retrofit of the communication layer, adding transmission capability to metres that already measure correctly. The distinction is technical and consequential.

The compliance gap is in connectivity, not measurement technology

The EED's requirement is specific: remotely readable data. Any metre that cannot provide it must either be replaced or retrofitted to do so. 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 metre and the communication layer, a distinction with significant implications for compliance costs and infrastructure longevity.

The overwhelming majority of legacy heat and hot-water metres 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 metres 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.

Transmission upstream can be handled via several standardised protocols depending on installation density, building topology, and backhaul requirements. NB-IoT is well-suited for sparse or geographically distributed installations where cellular coverage is reliable, and gateway density is insufficient. The choice of backhaul protocol is an engineering decision, not a product decision, and an interoperable data concentrator handles both.

Managing protocol heterogeneity at the edge

The primary engineering obstacle in European urban digitalisation is rarely the metres themselves. It is 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 programme can cleanly eliminate.

The technical solution is a protocol-agnostic data concentrator: a device that operates above the metre 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 metre 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 the 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 metre vendor's roadmap. The practical consequence is that metres 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 defence against vendor lock-in, a scenario that has proven costly for utilities that standardised on proprietary systems in earlier smart metre rollouts and found themselves unable to source compatible hardware when those vendors changed terms, exited markets, or were acquired.

Architectural resilience and OTA firmware management

A dedicated communication layer offers an operational capability that embedded metre 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. 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.

Proven at scale in high-density environments

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 metres 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 metres. 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: customer SIM cards loaded, settings applied, 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.

What the data layer enables beyond compliance

Meeting the 2027 deadline is the minimum requirement. The greater value of a well-designed remote metering infrastructure lies in what it enables operationally once the data is flowing.

For building operators, the elimination of physical metre access removes the single most common source of billing delays and estimated readings. A single inaccessible flat in a stairwell can cascade into deferred reconciliations across an entire building. Remote reading removes that dependency at the root.

For residents, monthly reporting as required by the directive enables behavioural change that annual billing cannot. Consumption anomalies, visible within weeks rather than at year-end, allow for earlier intervention on leaks, faulty equipment, or unexplained increases. The feedback loop tightens from 12 months to 30 days.

For grid operators and infrastructure planners, granular and continuous consumption data at the building level feeds directly into demand forecasting, load balancing, and the kind of infrastructure investment modelling that regulators across the EU are increasingly requiring as part of national energy efficiency reporting obligations.

The architecture decision determines the cost curve

The 2027 deadline is fixed. The cost of reaching it 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 metres 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.

About ACRIOS Systems

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. For more information, visit ACRIOS Systems.