The scope of the paper is to overview the different approaches for evaluation of urban infrastructure sustainability. In this context, urban infrastructure covers transportation, energy, water, sewage and information networks as well as waste management and blue-green infrastructure, in terms of both the supply and demand side. A common effort of partners in the European project “C8—Best Practice in Sustainable Urban Infrastructure”, developed under the Cooperation in Science and Technology program (COST), in brief COST C8, was focused on defining the methods, indicators and criteria for evaluation of sustainability, and resulted in a guidebook for decision-makers in local authorities. Here, the COST C8 matrix for simple sustainability assessment of urban infrastructure is applied to The Path (POT) case—a circular memorial and recreational park around the city of Ljubljana, Slovenia. The applicability and acceptance of the matrix in 43 other cases of sustainable urban infrastructure, collected in the COST C8 project, is presented and discussed.

The paper addresses the development of a bottom-up building stock energy model (BuilS) for identification of the building stock renovation potential by considering energy performance of individual buildings through cross-linked data from various public available databases. The model enables integration of various EE and RES measures on the building stock to demonstrate long-term economic and environmental effects of different building stock refurbishment strategies. In the presented case study, the BuilS model was applied in the Kočevje city area and validated using the measured energy consumption of the buildings connected to the city district heating system. Three strategies for improving the building stock in Kočevje towards a more sustainable one are presented with their impact on energy use and CO₂ emission projections up to 2030. It is demonstrated that the BuilS bottom-up model enables the setting of a correct baseline regarding energy use of the existing building stock and that such a model is a powerful tool for design and validation of the building stock renovation strategies. It is also shown that the accuracy of the model depends on available information on local resources and local needs, therefore acceleration of the building stock monitoring on the level of each building and continually upgrading of databases with building renovation information is of the utmost importance.

The paper presents the findings on end-users’ experiences and expectations about living in multi-family Nearly Zero-Energy Buildings (NZEBs). The survey in four European countries (Slovenia, Italy, Denmark and Germany) was part of EU Horizon 2020 project CoNZEBs (2017-2019) and addressed end-users living or thinking about living in multi-family NZEBs. Targeted end-users were living (as tenants or owners) in either ordinary buildings or in high performance buildings such as NZEBs (mandatory after 2020 according to Directive 2010/31/EU). In the survey, the following topics were addressed: the level of end-user’s understanding of the NZEB concept, the source and quality of information on NZEB from the end-users’ perspective, the importance of various apartment features for the end-users, perception of NZEB characterizing technologies, and decision triggers for living in NZEB. Concerns, doubts and eventual fears about living in NZEBs were studied to enable a tailored information for future end-users, to increase the demand for NZEB and beyond NZEB buildings and to improve their acceptability. To facilitate the living in NZEBs a guide for end-users was developed, explaining the “Myths” about NZEBs as well as presenting testimonials of current NZEB users in four participating countries.

Cultural heritage holds a constitutional status in Slovenia, immovable cultural heritage being its vital part. The most extensive categories of the Register of cultural heritage are buildings and settlements. In accordance with the principles of revitalizing and adapting heritage buildings to contemporary requirements with the aim of their sustainable conservation, energy renovation is also included in the integral approach. Such approach must adhere to cultural protection conditions and include measures that do not threaten the protected values. Energy renovation should be coordinated with other technical measures to meet the essential requirements for buildings. To support these efforts, the national Guidelines for energy renovation of cultural heritage buildings were introduced in 2016 as a manual that supports the conservators’ decisions and informs building owners and renovation contractors about the specifics of the approach to designing and implementing measures. At the end of 2023, the national research project V5-2358 (DEDIS) began, focused to provide an update of the guidelines. The additions will include refreshed chapters on the relevant national and European legislation, characteristics and regulation of cultural heritage protection, necessary preliminary investigations of the condition of buildings, and, as the main part, technical measures of renovation and their interdependence, with a special focus on the installation and use of renewable energy sources. The guidelines will consider the experiences of successful renovation projects and the results of an extensive interaction with key stakeholders through interviews and online surveys. The paper presents the preparatory activities leading to conceptualisation of the refined purpose, goals and content of the renewed guidelines.

Renovation of a building requires a comprehensive and targeted approach to managing the process from conceptual design to implementation and future use. Cultural heritage buildings are subject to specific legalities and restrictions in accordance with the conservation regime. The complexity of such a renovation process requires special knowledge and competence of the stakeholders involved. The key is constant and coordinated cooperation among the designer, the cultural heritage protection authority, the investor, the users, the supervisor and the contractor. This rationale inspired the creation of a model of the comprehensive energy renovation process, balancing heritage conservation with energy efficiency through nine key elements and quality guidelines, developed within the LIFE IP CARE4CLIMATE project. The model includes detailed steps of the renovation with quality guidelines for the conceptual design, inspection of the building's condition, financial planning, comparison of variant renovation measures, energy performance analysis and investigation of several other aspects, for instance fire and electric safety, earthquake resistance and the quality of the indoor environment. The model includes support to the investor in the preparation of tenders, contractor selection, supervision, and building management and monitoring plan. This innovative model has been successfully implemented in renovation of several heritage buildings in Slovenia. A more detailed description of its implementation in practice is presented on an award-winning renovation project of heritage building in Ljubljana, Slovenia.