At Aiguasol, we have collaborated with the Uliazpi Foundation with the objective of decarbonizing the heating and domestic hot water (DHW) systems of its centers in Zubieta (Hondarribia) and the foundation’s buildings in Ategorrieta (Donostia).

The Uliazpi Foundation, a public entity of the Provincial Council of Gipuzkoa (Basque Country), provides services and support that enhance the quality of life of people with functional diversity and their families. Working with them has allowed us to deliver responsible energy solutions with a direct impact on the community, combining sustainability, technology, and social transformation.

The Zubieta center is already equipped with aerothermal systems and a 250 kW biomass boiler, designed and installed by Aiguasol, which supply heating and DHW to the residential buildings, the heated swimming pool, the offices, and the kitchens. However, diesel boilers are still in use as backup, and one of the goals of our collaboration has been to provide a more sustainable alternative energy system to phase them out completely. To this end, we have assessed various technological solutions, such as booster heat pumps (which make it possible to recover surplus heat from the existing aerothermal systems, reducing unnecessary consumption and energy losses) and the installation of an additional biomass boiler.

In parallel, at the Uliazpi Foundation’s Ategorrieta center, we have led the modernization of the existing centralized generation system through the development of the executive project, which includes the installation of aerothermal systems to complement the output of the existing gas boilers, thereby improving the energy efficiency and sustainability of the complex.

To design the system, we first carried out a comprehensive analysis of the thermal demands of the three buildings that make up the center. We reviewed the climate file used for energy simulations, updating it to reflect current climatic conditions in Donostia. To model building performance, we used DesignBuilder, which enables the definition of building geometry and construction characteristics, as well as visualization and extraction of results. EnergyPlus, serving as the calculation engine, performed hour-by-hour thermal simulations for an entire year. We considered the uses associated with each building type and simulated heating demands both for the entire site (Careaga, Uliazpi, and Didactic buildings) and individually. From these models, we obtained detailed information on thermal demands and the required capacities for heating and pool-related needs.

Once these parameters were defined, we designed the generation system based on a hybrid model combining aerothermal technology and gas boilers, managed through an Energy Hub that activates the optimal generation system at each moment depending on whether the demand is for high temperature (radiators, DHW) or low temperature (pool), optimizing overall operation.

Additionally, we proposed installing an air handling unit (AHU) for the pool, which will enhance indoor air quality and hygiene while significantly improving dehumidification in the pool area. This AHU is supplied by a new chiller with heat recovery, which will utilize the machine’s residual heat to feed the heating circuit when producing cooling.

This comprehensive approach enables us to plan more efficient and sustainable energy solutions, ensuring that each building is equipped with optimal and environmentally responsible energy, heating, and DHW systems.

Projects like this remind us how innovation can improve people’s lives, and how every step toward decarbonization is also a step toward a more responsible and inclusive future.