A need for the refurbishment and renewal of the existing building stock has been in focus for many decades, principally because of excessive global energy consumption and pollution. This paper presents a methodology and the results of analysis of choices of realizable sets of timber frame prefabricated insulation elements for major renovation of apartment buildings. Numerous combinations of elements with different characteristics were analyzed by applying measurements, interviews, and building performance simulation software, and thereupon their performance, installation eligibility, and concurrent cost levels were compared. Mineral wool board with a special wind barrier facing was found to be the best material as a wind barrier from the perspective of hygrothermal performance. An air and vapor barrier should have sufficient vapor permeability to allow dry-out of constructional moisture. It is possible to renovate apartment buildings to meet the nZEB energy performance requirements and their moisture safety can be guaranteed without paying high relative difference cost. Calculations showed that the global cost was lower for solutions with some mold growth risk. Great care is needed when decreasing costs without simultaneous hygrothermal analyses. The facade cladding was found to have the highest influence on the initial cost of the prefabricated insulation element.

Construction and demolition waste constitute more than one-third of the total waste generated in the European Union. The pursuit of sustainable renovation must progress further to encompass elements that ensure reuse or recyclability. A fundamental transformation, involving extensive renovation and a transition to circular renovation practices, is indispensable in effectively addressing the pressing challenge of decarbonization for the entire building stock in Europe. In this study, we have developed a circular deep renovation solution using prefabricated modular external additional insulation elements to achieve a nearly Zero Energy Building (nZEB). Circular prefabricated modular external additional insulation elements were formulated, manufactured, and installed. The potential for disassembly and reutilization of materials was developed and demonstrated for both a prototype and the complete deep renovation. The analysed prefabricated modular solutions exhibited greater potential for circularity compared to the traditional External Thermal Insulation Composite System (ETICS) due to their superior demountability and reusability characteristics. The overall cost of the renovation, which included the installation of a new heating system, replacement of water and sewer pipes, addition of 50 kW photovoltaic (PV) panels on the roof, installation of new balconies, addition of a balanced ventilation system with heat recovery, and replacement of the electricity system in common areas, amounted to 505 €/m². Following the deep renovation, the Energy Performance Value was measured to be 92 kWh/(m²·a), resulting in an EPC class of A. This implies that the building now meets the requirements for nZEB in accordance with Estonian legislation, with no performance gap.

The primary objective of this study is to evaluate possible ventilation solutions for nZEB multi apartment buildings in three European geoclusters. Geo-cluster concept illustrates trans-national areas where strong similarities are found in terms of climate, culture, construction typologies and other factors. Paper presents comparison of ventilation needs for the same case study building located in Denmark, Estonia, Latvia and Portugal. The economic and technical comparison of different ventilation systems are presented as well. Special focus is attended to develop introduction of modular solutions and integration of ventilation ducts into external insulation as this can serve as a complex solution including both external constructions and engineering networks. Presented modular solution includes prefabricated insulation panels with integrated ventilation ducts. This paper is prepared in scope of work done within EU HORIZON2020 MORE-CONNECT project. Research methodology is based on data analysis provided by project partners as well as practical calculation. Compilation of ventilation air volume requirements according to the local regulations for Latvia, Estonia, Portugal and Denmark has shown significant difference in design air change rate in project countries. The financial analysis reveals the price difference between various ventilation strategies and provides discussion topic regarding ventilation strategies in nZEB buildings

H2020 project DRIVE0 (Driving decarbonisation of the EU building stock by enhancing a consumer centred and locally based circular renovation process) aims to come to a decarbonisation of the EU building stock and to accelerate deep renovation processes by enhancing a consumer centred circular renovation process in order to make deep renovation more attractive for consumers and investors, more environmental friendly. Circular renovation concepts and process will specifically be developed and implemented in the seven demonstration cases in seven countries, representing all climatic zones in Europe