Riga City Hall is undergoing a transformation employing a detailed analysis to guide the retrofitting efforts. Demo partners REA and Riga Technical University with the consortium partners are working hard to lay down all the ‘blueprints’ for the installations to come.

Achievements and Progress

• Permit Acquisition: Successfully obtained the necessary approvals for installation and material use.
• Collaborative Planning: Finalized hardware and communication architectures and designated the final demonstration area.
• Material and Access Approvals: Approved the materials list and arranged all necessary access permits.
• Solution Design: Final installation design to ensure accurate measurement of parameters and effective equipment control, overcoming challenges related to communication capabilities.

The past months have been marked by energy performance assessments, procurement finalization, and stakeholder engagement. Enhancing the energy performance of a historic government building required a comprehensive energy assessment. The Riga team developed a Baseline Energy Performance Certificate to identify inefficiencies and guide retrofitting efforts.

Combining Heritage with Sustainable Energy

One of the most exciting recent developments is the integration of Building Integrated Photovoltaic (BIPV) systems. These systems will provide sustainable energy while preserving the architectural integrity of the structure. During installation, the location of the BIPV installation had to be adapted to better meet the energy needs of the building. This shift ensures maximum efficiency while remaining within the constraints of the historical preservation requirements.

As the photovoltaics installations move forward, smart blinds optimizing indoor lighting and temperature regulation are being developed by PELLINI to improve energy efficiency.

Winter Thermal Comfort Monitoring & Environmental Analysis

In February 2025, the RTU team conducted winter indoor thermal comfort monitoring at Riga City Hall at 5 floors each featuring different works station setup. Spot measurements were done over 2 winter days between 9 AM till 4 PM, hourly across 10 work stations. The team analyzed temperature differences across surfaces and work stations during working hours by measuring:

• Ambient air temperature,
• Globe temperature,
• Relative humidity,
• CO2 concentration,
• Vertical illuminance,
• Surface temperatures (nearest façade/outdoor facing wall, window frame, desk, floor, ceiling).

These comprehensive measurements help identify thermal asymmetry and indoor environmental quality issues. This information is important for assessing the user comfort and optimizing energy efficiency strategies.

This allowed the pinpointing of localized discomfort caused by:

• cold radiation from exterior walls,
• uneven heating distribution, or
• excessive solar gains near windows

Continuous measurements were also conducted over 24 hours to measure the variability in temperature, humidity, and CO2 levels at two work stations.

Next Steps: Installations & Performance Optimization

With significant progress made in planning and procurement, the next six months will focus on:

• completing procurement and installation of devices and sensors, including BIPV and smart blinds
• Full-scale deployment of sensors
• Live data collection to track energy savings and comfort improvements

The last step signifies the shift towards data collection and performance optimization. This way, the project team can systematically evaluate the impact of retrofitting measures on energy consumption and indoor environmental quality at Riga City Hall.

Beyond technical advancements, knowledge sharing remains a key priority. Findings from the Riga City Hall demonstrator will contribute to a scientific publication, adding to global research on energy-efficient retrofits for historic buildings. Additional outreach and dissemination initiatives will ensure that these insights benefit local municipalities, European energy policymakers, and sustainability practitioners.

With significant progress already made, the Riga City Hall project is poised to serve as an example of how smart technologies can enhance the sustainability of Europe’s historic architecture—without compromising its heritage.

Riga City Hall (Rātsnams), located in the historic old town of Riga (a UNESCO heritage site), serves as the main administrative building for the Riga city municipality. Originally built in the mid-19th century and reconstructed in 2004, the City Hall is now a crucial part of the SMARTeeSTORY project. Alongside various specialized EU partners and the research team at Riga Technical University's Institute of Sustainable Building Materials and Engineering Systems (RTU), the city is working to significantly improve the building’s energy efficiency and smartness.

The main project goals are:

• Upgrade heating, cooling, ventilation, lighting, and shading systems.
• Integrate Building-Integrated Photovoltaics (BIPV) for renewable energy.
• Implement the SMARTeeSTORY energy management system.

An extensive energy audit conducted in late 2023/early 2024, which included a comprehensive analysis of heating, ventilation, and air conditioning (HVAC) systems, highlighted areas for efficiency improvements. The energy consumption data from 2017 to 2022 showed significant variations, and based on the audit findings, the following measures were proposed:

• Adding a 200 mm thermal insulation layer to the uninsulated exterior wall facing the unheated tower space to achieve a thermal transmittance value of U=0.14 W/m²K.
• Installing energy-efficient glazed constructions, including solar glazing on selected floors, to enhance airtightness and reduce infiltration.
• Upgrading the HVAC systems based on technical survey recommendations to ensure proper operation and substantial energy savings while maintaining optimal indoor environmental conditions.
• Replacing all lights with energy-efficient LED solutions.

Substantial peaks in heating energy consumption during colder months indicate significant potential for savings through the proposed measures. Implementing these solutions is expected to substantially reduce the building's primary energy consumption and carbon footprint.

The energy audits provided valuable data on the building's energy performance, highlighting areas for improvement. A meeting at the end of February 2024 with involved project stakeholders—Riga City council project coordinators, RTU, energy auditors, as well as invited architects and consultants—discussed and outlined further steps of action.

The ongoing demo activities at Riga City Hall demonstrate how historic buildings can be retrofitted with modern, energy-efficient technologies while preserving their architectural heritage.