Bridging Simulations and Reality: Eurac's Innovative Approach to Smart Building Energy Control

Eurac Research, a leading applied research center in Bolzano, Italy, has just released a pivotal study that marries large-scale European simulations with rigorous laboratory experiments to advance smart energy management for retrofitted buildings. Titled "Modelling thermocline dynamics in thermal energy storages: A computationally efficient reduced-order model approach," the paper introduces a groundbreaking reduced-order model (ROM) for thermal energy storage (TES) systems. TES refers to technologies that store thermal energy—typically as heat or cold—for later use, often in water tanks that leverage natural stratification where hot and cold layers separate, forming a thermocline interface.

This innovation is particularly timely as Europe grapples with its aging building stock. Over 85% of EU buildings were constructed before 2000, and about 75% suffer from poor energy performance, contributing to 40% of the bloc's total energy consumption and 36% of energy-related greenhouse gas emissions. With the EU Green Deal pushing for climate neutrality by 2050 and the revised Energy Performance of Buildings Directive (EPBD) mandating zero-emission standards for new buildings from 2030 and all stock by 2050, retrofitting existing structures is non-negotiable. Yet, current renovation rates hover around 1%, far below the tripling needed by 2030.

The study targets residential buildings enhanced with heat pumps and renewables, common in retrofits. By enabling precise, real-time control, it promises to slash energy use while boosting grid flexibility.

The Urgent Need for Smart Retrofits in European Buildings

Retrofitted buildings—those upgraded for better efficiency without full demolition—face unique hurdles. Legacy infrastructure limits invasive changes, especially in historic structures prevalent across Europe, from Alpine villages to urban centers. Integrating smart systems like Internet of Things (IoT) sensors, artificial intelligence (AI), and advanced controls can optimize heating, ventilation, air conditioning (HVAC), and renewables, but demands models that balance speed and precision for real-time decisions.

Traditional high-fidelity simulations using computational fluid dynamics (CFD) or multi-nodal methods excel in detail but take hours to run, unsuitable for Model Predictive Control (MPC). MPC is an advanced algorithm that forecasts building energy needs over a horizon (e.g., 24 hours), optimizes actions like heat pump operation or TES charging, and adjusts dynamically. Simpler lumped models ignore stratification, leading to inefficiencies. Eurac's ROM fills this gap, using physics-based grey-box modeling with just two thermal nodes to mimic thermocline behavior accurately.

In Europe, where winters strain grids—as seen in recent crises—such tools enable demand-side flexibility, shifting loads to off-peak times and integrating variable solar or wind power. For instance, TES can store excess daytime heat from panels for evening use, cutting peak demand by 20-30% in simulations.

Deep Dive into Eurac Research's Methodology

The research team, comprising Mohammad Hossein Fouladfar, Tim Diller, Francesco Turrin, and Roberto Fedrizzi from Eurac's Institute for Renewable Energy, crafted the ROM through a hybrid approach. First, physical principles govern energy balances in the tank's upper hot node and lower cold node, with the thermocline modeled as a moving boundary. A single calibration parameter ensures transparency and ease.

• European-Scale Simulations: Tested across diverse climates (Mediterranean to Nordic), accounting for weather variability, occupancy patterns, and grid prices. A nine-hour cycle mimicked heat pump charging/discharging, completing in 0.015 seconds versus minutes for benchmarks.
• Laboratory Validation: Conducted at Eurac's Energy Exchange Laboratory, a state-of-the-art facility simulating real HVAC interactions. Tests spanned charging (hot water input), discharging (cold draw), and mixed cycles under varying flows and temperatures.

Results? The ROM cut root mean square error (RMSE) by up to 46% and mean absolute error (MAE) by 44% over finite difference models, while running 100 times faster. Tim Diller notes, "Our model preserves essential physics for real-time optimization, transforming TES from niche to mainstream."

Key Findings: Speed, Accuracy, and Real-World Readiness

The study's benchmarks reveal transformative potential:

• Two orders of magnitude faster computation, ideal for MPC horizons.
• Superior thermocline prediction, crucial as stratification boosts TES efficiency by 15-25% over mixed tanks.
• Robust across scenarios, with minimal calibration—plug-and-play for retrofits.

In lab trials matching real measurements, the model forecasted temperatures within 1-2°C, enabling precise control that could yield 10-20% energy savings in heat pump systems. For retrofitted buildings, this means retrofitting TES (e.g., 1-5 m³ tanks) alongside insulation and efficient windows becomes viable, aligning with EPBD trajectories.

Photo by Barbara Horn on Unsplash

Applications in Retrofitted and Historic Buildings

Eurac's work dovetails with projects like FuturHist, a Horizon Europe initiative led by Eurac, focusing on typology-based retrofits for historic buildings. Historic stock—20-30% in cities like Bolzano or Kraków—demands conservation-compatible solutions. FuturHist's toolkit includes hygrothermal simulations and life-cycle assessments (LCA), where Eurac's ROM enhances active strategies like smart HVAC and renewables.

Real-world cases abound: In Slovenia's Infinite project, a 1982 social housing block retrofitted with eco-materials and smart controls cut energy by 40%. France's social residential studies show 36-41% heating reductions via similar tech. Norway's heritage retrofits prove TES viability even in protected facades.

Challenges persist: upfront costs (€5,000-20,000 for TES), data silos, and skills gaps. Yet, benefits—payback in 5-10 years via savings (€500-1,500/year) and incentives like EU Recovery Funds—outweigh them. MPC unlocks ancillary services, selling flexibility to grids for extra revenue.

Stakeholder Perspectives: From Researchers to Policymakers

Building owners praise scalability; a Bolzano retrofit pilot integrated TES-MPC, reducing bills 18% amid 2025 gas spikes. Utilities see grid relief—smart buildings could flex 10-15% of peak load EU-wide. Policymakers align it with EPBD's national building renovation plans, mandating minimum performance from 2030.

Experts like Daniel Herrera (Eurac, FuturHist coordinator) emphasize typology approaches: "Classify by era/materials, simulate en masse, deploy smart controls." Challenges include interoperability (e.g., BACnet standards) and cybersecurity, but EU's Smart Readiness Indicator rates buildings on such features, incentivizing upgrades.

Technical Breakdown: Implementing TES and MPC Step-by-Step

Deploying this tech involves:

1. Assessment: Audit building via energy modeling (e.g., IDA-ICE software).
2. TES Install: Stratified tank post-heat pump, sized 20-50 liters/person.
3. Sensors: IoT for temps, flows, occupancy.
4. MPC Setup: Embed ROM, forecast weather/prices via APIs.
5. Optimization: Minimize costs/emissions over horizon, execute via actuators.
6. Monitor: Dashboards for tweaks, grid participation.

In retrofits, modular TES fits basements, complementing insulation (U-values <0.2 W/m²K).

Broader Impacts: Grid Stability and Climate Goals

EU-wide, scaling could save 100-200 TWh/year by 2030, per IEA estimates for TES. It supports variable renewables—store summer solar for winter. For vulnerable households, lowers bills amid volatility.

Historic contexts shine: FuturHist Academy trains pros in Kraków (Sept 2026), blending Eurac models with heritage tools.

Photo by Lukas S on Unsplash

Future Outlook: AI, Policy, and Careers in Smart Energy

Next: AI-enhanced MPC for multi-building clusters. EU's Horizon Europe funds pilots. Challenges—data privacy (GDPR), upskilling—yield opportunities in higher ed jobs like research assistantships at Eurac or partners.

Professionals eyeing research jobs or career advice in sustainability will find demand surging. Rate professors via Rate My Professor for top programs.

This study positions Europe at smart energy forefront, blending innovation with practicality for a greener built environment.