Nowadays the building sector is a significant energy consumer. As the part of the long-term energy policy of the European Union was introduced Energy Performance Certification of Buildings (EPCB further). It was an important step because only low-energy buildings can obtain a building permit from 2020. In order to comparability of buildings it was important to create an index, which unequivocally features each building, and contains every energy performance data about the building. The purpose of this research is developing a methodology for a simulation-result-based EPCB in order to it can be prepared in case of under design buildings, too. This article describes the method itself, collected directions which be able to decrease energy consumption in existing buildings, and directions which be able to reduce simulation-based energy consumption in buildings under design. The paper shows some example about simulation based results and results of optimization directions of energy consumption.

The Electrical Engineering and Mechatronics Department has developed a Building Mechatronics Research Center, where professors and researchers engage in several projects regarding the energy consumption of buildings, which are focused on the importance of the economic return of building modernizations via simulations. In this article, the prevalent energetic modernization of buildings and their payback period in Hungary are introduced.

The aim of this paper to introduce a computer based optimization method what is able to improve the energy efficiency of existing or new buildings. The proposed method is a mixture of building physics simulation and multi value optimization method. The building is considered as a multi-variable nonlinear system. Different optimization directions are examined, what is lead to suboptimal solution. Combination of suboptimal method are shown to illustrate globally optimal solution. In Hungary the most energy consumption is in building sector. More than half of Hungarian buildings-included the residential, office, commercial and public buildings-were built before 1980s. Because old and poor condition buildings the energy efficiency of the building sector is low. In this article we present some energy retrofit opportunities and simulations about a Hungarian office buildings. In this research we simulated nine retrofits and searched the best opportunity for reducing energy usage.