From Lab to Life with ThumbsUp

Why thermal energy storage?

Considering that close to 80% of the energy consumption in households goes to comfort heating and domestic hot water (DHW), thermal energy storage (TES) is key in accelerating the energy transition, particularly when used to maximise the effect of renewable energy sources (RES).

Unfortunately, the sun does not always shine when we need it to. It is usually strongest in the middle of the day, when most people are at work or school, and do not need to heat their homes, take warm showers or wash the dishes. However, in the evenings when people come home and start consuming energy, there are little or no rays left. Hence, the renewable energy technologies installed in people’s homes are not optimally used and do not have the effect they should. To balance and even out the differences between energy production and energy use, TES can play a crucial role in balancing the grid one building at a time.

ThumbsUp is developing these types of technologies for residential buildings to provide them with more control and flexibility over their energy consumption, while in turn relieving both electricity and district heating networks.

New approach to solve an old challenge

Even though compact TES is not a new technology per se the available products on the market are very expensive, not very efficient, nor environmentally friendly. To solve these challenges, 20 partners from 9 different European countries are working together to design, develop and test two types of solutions that will allow households to store heat and cold on a daily or monthly basis.

For daily storage, the FractLES solution combines innovative bio-based phase change materials (PCMs) derived from animal waste with optimized roll-bond heat exchanger plates and advanced control logic that ensure stable, efficient, and safe performance. Designed for efficient heat storage and transfer, the system leverages sustainable materials and smart integration to enhance energy performance and reduce environmental impact.

For monthly storage, the high energy density solution SorTES is an advanced thermochemical energy storage system that uses composite sorbent materials to store and release heat through reversible chemical reactions. The technology integrates a newly scaled-up manufacturing process capable of producing nearly one tonne of composite sorbent, a redesigned reactor to maximize material capacity, and a novel model-based approach for monitoring State of Charge (SoC) and State of Health (SoH) of these technologies.

From lab to life

The goal is clear, but the process implies a long series of trial and error that allow continuous improvement and validation. One of the most important steps in the process is taking the prototype from a controlled lab environment to a real-life setting with all the risks, unforeseen complications and variabilities that it implies. For this, the ThumbsUp FrancLES and SorTES solutions are being tested in three demonstration sites with different climate zones and building typologies.

Two of the test sites are located in the city of Valladolid, Spain. The first is a single-family house, where a very courageous family has agreed to install a prototype in their house and allow project partners to monitor and measure the storage solutions performance and actual impact on the house’s energy consumption and costs – as it is being done in all the demonstration sites.

A newly refurbished convent that has been converted to an elderly care home makes up the second demo site. With rather stable and repetitive behavioural patterns the residents of the home are contributing to building a more sustainable future for generations to come.

The third is the HSB Living Lab in Gothenburg, a student home located on the Chalmers campus. Equipped with thousands of sensors, its primary purpose is to serve as a user-centred, open-innovation ecosystem that enables actors to collaboratively test sustainable housing technologies, materials, and living practices in a real-world residential building.

ThumbsUp solutions installed at the demo sites should not be noticeable to the residents. The systems will be tested for a year, first with a simpler time-controlled charging and discharging and then adjusted according to the monitored performance.

“We want to show that thermal energy storage not only works technically but can be smoothly integrated into buildings and contribute to a more stable energy systems,” says Ola Gustafsson, Project Manager at RISE.

Behind the scenes: blood, sweat and tears

As expected, the installation of these cutting-edge porotypes in real homes has not been without its challenges. To provide some behind the scenes insights on the process, we interviewed Carlos Gabriel Garcia Campos, Innovation Engineer at Veolia Spain and responsible for overseeing the installation and monitoring of the ThumbsUp prototypes in the three demonstration sites. Here are some of the main take-aways so far.

I.               Seamless integration with the existing infrastructure is not as easy as it seems.

“We mainly struggled with limited building energy management systems (BEMS) and communication capabilities in the single-family home. Small heat pumps and photovoltaic (PV) systems often lacked smart or standardized interfaces, and accessing their data was not always straightforward.” Says Mr. Campos, who also lifted the practical issues related to space constraints.

II.              Good communication and thinking on your feet are necessary to keep on moving forward.

To quickly solve the issues that arose, the team worked closely with the technology providers to better understand their systems.
“For PV inverters, we worked with suppliers to agree on simple, standardized data-access methods. For integration issues, we increased coordination across all actors—clients, maintenance teams, designers, manufacturers, installers, and IT—so we could find optimal solutions together” explains Mr. Campos

III.             Theory vs reality

When asked why it is important to test these prototypes in real living environments, Mr. Campos responded that “real homes reveal practical challenges and user-centric insights that cannot be captured in a lab. Testing in real environments helps validate flexibility, compatibility, and overall performance under real usage patterns, which is essential for meeting EU energy and environmental targets.”

IV.            Driving European innovation with scalable solutions

This complex process is necessary to develop ground-breaking technologies that will facilitate the decarbonisation of the energy systems. Unfortunately, it is costly with a varying success rate, which is why receiving support from the European Commission is crucial.
As Mr. Campos clarifies “EU funding allows us to take on innovative, high-risk research more confidently. It provides resources, collaboration opportunities, and a supportive framework to develop scalable solutions that can accelerate the energy transition.”

The ThumbsUp project runs until December 2026. The aim is to develop TES solutions that are both scalable and economically feasible within the EU, and that can be used by everything, from housing associations to larger property owners. The lessons learned from installing prototypes in European test sites show that transnational collaborations between public, private, research actors, as well as SMEs drive technology development, strengthen networks and facilitate knowledge sharing.