Dear Colleagues,

In residential buildings in Europe is used around 40% of the total amount of energy produced, of which more than 70% for space heating. Therefore, reducing energy consumption in this sector is constantly gaining importance, especially in the face of the obligations of individual European Union member states in the field of increasing energy efficiency and the use of renewable energy sources (RES).

Rationalization of heat consumption should be taken into account in new buildings already at the stage of designing energy-efficient heating ventilation and air conditioning (HVAC) and domestic hot water preparation (DHW) (also with the use of RES), and then continued through education and full involvement of residents in the process of effective use of the supplied heat or electricity.

On the other hand, in the majority of existing buildings, the reduction of heat consumption has already been achieved by implementing thermal modernization of the building envelope, often combined with a certain scope of modernization of the HVAC systems (e.g. installation of thermostatic radiator valves). Therefore, further modernization measures aimed at further increasing the level of energy efficiency in this type of buildings will now focus, in particular, on the modernization of the HVAC system and domestic hot water preparation, education of residents, and improvement of control and automation of delivery, storage and use of energy.

However, there is often a lack of reference values that would define the level of heat reduction that could be achieved by a given retrofit measure and that would be confirmed by long-term field tests.

The aim of this Special Issue is to incorporate works on energy efficiency and/or integration of RES in existing buildings, supported by (if possible): a) calculation of the time of execution of modernization works; b) analysis of difficulties during the implementation of modernization works for users; c) calculation of Simple Pay Back Time (SPBT).

Manuscripts related to below specific topics are also warmly welcome for this special issue:

• Tests and simulations of HVAC systems and their components aimed at improving the energy efficiency of the building
• Long-term simulations of modernization changes aimed at improving energy efficiency
• Analysis of the impact of user behavior and HVAC system operation control on the energy efficiency of buildings
• Energy, financial and environmental costs of operating HVAC systems and RES in buildings

Dr. Tomasz Cholewa
Prof. Alicja Siuta-Olcha
Prof. Dr. Dorota Anna Krawczyk
Dr. Łukasz Amanowicz
Dr. Michał Turski
Guest Editors

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