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Renovation of existing buildings has been highlighted as an essential action in the European Green Deal and in the latest revision of the EPBD to achieve energy efficiency targets. Renovation Wave strategy aims to double the deep energy renovation rate in EU by 2030, while specifically targeting the worst-performing segment of the existing building stock. The objective of this study was to assess the energy performance of deep renovation concepts on single and multi-family houses in three different geographical settings – Germany, Italy and Estonia. Typical German 1970s buildings were used as a baseline reference, and it was shown that very similar renovation concepts can be successfully applied across Europe that provides good bases to develop standardized solutions. Energy performance of two common renovation concepts was assessed both with national calculation methodologies and dynamic simulation with harmonized inputs and detailed heat pump plant models. The renovation concepts included improved envelope insulation and airtightness, switched to heat pump systems and heat recovery ventilation as well as incorporated on-site PV while complying with nearly zero-energy requirements for major renovations in all three countries. National energy calculation methodologies showed good accuracy for before the renovation situation but failed in many cases to calculate adequately NZEB renovation concepts with heat pumps and PV, indicating the development needs towards hourly calculation and more detailed treatment of heat pumps.

Revised EPBD directive has set ambitious targets for renovation. It is stated that Member States shall establish a long-term strategy facilitating the cost-effective transformation of existing buildings into nearly-zero energy buildings. The long-term strategy should set out a roadmap with a view to the long-term 2050 goal of reducing greenhouse gas emissions in the European Union. This creates the need for cost-efficient renovation solutions which can be implemented in large scale. The impact assessment shows that roughly a doubled renovation rate of 3 % would be needed to accomplish the energy efficiency ambitions in a cost-effective manner. The objective of this study is to specify renovation concepts with adequate heating and ventilation, based on Estonian and German apartment buildings and corresponding local solutions. Energy performance and sizing analyses were conducted for selected multifamily apartment buildings typical for 1960-70es with three different renovation concepts. Energy calculations were conducted with national energy calculation methods and national energy requirements for major renovation. In the renovation, the building envelope insulation, air tightness, and heating and ventilation systems were improved so that the renovated building complies with national nearly zero-energy requirement for major renovation.

Abstract: When modelling buildings, solar radiation has a large impact on the thermal balance because it usually heats the rooms. In radiant systems that are used for heating and cooling buildings, solar radiation has a large influence both on indoor temperatures and on the efficiency of the radiant system. Many analyses have already been carried out in order to study how beam and diffuse radiation can be distributed in a room. One of the most difficult issues, when modelling room thermal balance, is how to simulate the solar radiation when it enters the room, which in turn depends on the reflectance characteristics of the surface finishing elements. In this study, four different radiation models have been applied in order to solve an overall detailed, dynamic thermal balance in a room with pipes embedded in the floor. Two of the models are detailed; the other two consider the radiation entering the room to be diffuse radiation. As for the behaviour of the impinging solar radiation on the covering materials in a room, measurements have been carried out to determine the reflectance coefficients, which will be used in simulations for characteristic materials used in buildings. Results of the simulations show that a simplified model, which considers solar radiation as uniformly distributed in a room, cannot be used for a detailed comfort analysis; however, when looking at the cooling output of a radiant floor system at the design stage, a simplified model can predict energy transfer to a certain level of accuracy. Moreover, results coming from combined measurements and simulations show that the reflectance characteristic of the covering materials does not affect the cooling capacity of the radiant floor systems, since the most important parameter for cooling performance is the thermal conductivity of the covering layer. [Copyright &y& Elsevier]