Enhancing optimal exploitation of solar energy in Nordic cities through the digitalization of the built environment

A large portion of solar energy remains unexploited. This is also the case in the Nordic countries where climate challenges, legal and cultural barriers, and economic constraints prevent optimal exploitation of solar energy. In this context, the project HELIOS aims to turn the Nordic conditions into unique opportunities to accelerate the use of solar energy and the deployment of solar systems in the Nordic built environment through digital techniques using Trondheim as a pilot city. HELIOS aims to optimize the use of solar energy in Nordic cities through digitization of the built environment. It aims to facilitate the mapping of solar radiation to optimize the use of solar energy at several levels, ranging from facades and individual buildings to neighborhoods and entire cities. The HELIOS open access user-friendly 3D model platform has twofold goals: (i) enabling solar irradiation mapping for optimal exploitation of solar energy at multiple spatial scales, ranging from facades to buildings, neighborhoods, and whole city; (ii) predicting solar energy generation at multiple temporal domains, ranging from short (daily), mid (50 years) and long (100 years) term under climate change scenarios. At the city scale, HELIOS aims at visualizing areas, parts of the city, and urban surfaces (roofs and facades) receiving high solar irradiation by identifying areas with high solar energy potential to favoring self-consumption and by providing urban planning recommendations, guidelines, best practices. At neighborhood scale, HELIOS evaluates solar irradiation and generation in new, consolidated, and heritage-constrained built environments through high-level 3D models containing detailed roof structure and facade models with walls, windows, balconies, and other facades' elements. Advanced analyses are conducted on exemplary Nordic building stock considering complex urban phenomena (dynamic shadowing, solar inter-building reflections) and related issues (high surface temperature, airflow) due to existing urban fabrics. The process is easily replicable in other follower neighborhoods. HELIOS is connected with many international activities and networks, such as the IEA Task 63 "Solar Neighborhood Planning" where the first definition of Solar neighborhood has been provided, IEA PVPS Task 15 “Enabling Framework for the Development of BIPV”, and national research centers (e.g., FME SOLAR) and projects (e.g., KPN SolKit - A toolkit for sustainable photovoltaics integration in the Norwegian built environment). HELIOS has the ambition to increase the social acceptance of solar energy and stimulate a common arena for urban stakeholders’ engagement, authority, and citizen participation.

The 2030 Climate Target Plan promotes sustainable cities through, among the others, increased solar energy share at the current state and in the future climate scenarios. However, a large portion of the solar energy remains unexploited also in the Nordic countries which share the same climate challenges, legal and cultural barriers, and economic constraints, which are factors preventing optimal exploitation of solar energy. In modern cities, façades have a high potential to collect sunlight, especially at high latitudes since the sun maintains an optimum angle of incidence for longer making the solar systems' integration into facades even more favorable than in the rest of Europe. Moreover, employing vertically mounted solar systems in high latitudes presents better-operating conditions since they are rarely covered by snow in the winter, which brings an increased energy generation to match electricity consumption and price peaks. In this context, HELIOS aims to break the paradigm of solar energy use in the Nordic climate, by overcoming the common false beliefs that have discouraged the adoption of solar systems for a long time in Scandinavia. HELIOS has the ambition to turn the Nordic conditions into unique opportunities to accelerate the use of solar energy in the Nordic built environment using Trondheim as a pilot city. HELIOS develops an advanced co-simulation approach by combining numerical equations, algorithms, and simulation tools with observational data, in-field experimental campaigns, and monitoring of solar irradiance. The solar cadaster, grounded on this approach, contributes to change the role of solar energy in the Nordics by demonstrating the unexploited solar energy potential and expanding scientific knowledge dealing with complex urban phenomena (e.g. solar inter-building reflections, shadow cast) in various spatial domains (building, neighborhood, and city) and predicting solar energy potential at multiple temporal terms (short, mid and long).