BACS: energy performance and technical-economic analysis of HVAC technologies

In Europe, buildings operation causes 40% of energy consumption and 36% of greenhouse gas emissions. For this reason, the European Union’s Energy Performance of Building Directives (EPBD) provides policies aimed at optimizing the energy efficiency in buildings. To achieve the goal of optimizing the energy performance of buildings, the directive identifies several technological solutions that can be used. One of these technological solutions and the topic of this thesis are the Building Automation and Control Systems (BACS), whose purpose is to adapt the operation of technical building systems on the real behavior of users according to the external environmental conditions. To develop this work the EN ISO 52120 standard has a relevant importance, since it provides the list of BAC systems, the method to define the BACS efficiency classes, and the detailed and simplified methods to assess the effect of BACS on the building energy performance. This work is the result of a collaboration with C2R Energy Consulting, a consulting company in the energy sector. The goals are twofold. The first goal is to evaluate the ability to simulate the BACS functions with two different energy modeling tools; Edilclima EC700, which uses a simplified dynamic calculation model, and EnergyPlus – DesignBuilder, which uses a detailed dynamic calculation model. First, the work illustrates which functions can be simulated and at what relative implementable level. A short guide to the actual simulation of the functions is also provided. A group of classrooms of Politecnico di Torino are modeled with the two software tools to simulate the presence of some of BACS functions used for HVAC and blind control and to evaluate their effects on the energy performances and the energy savings of the building. The thesis provides a comparison of sensible heating loads, sensible cooling loads and ventilation electric power results, obtained from the simulations made with the two software tools. The benefits of having high-energy performance BACS functions are highlighted. As well, the strengths and weaknesses of the two software tools are analyzed.. The results show that a high BACS efficiency class allows to reduce the energy consumption both in terms of sensible heating and cooling loads and in terms of ventilation electric power. The second goal is to analyze the economic feasibility of BACS installation and to provide a more realistic evaluation of the cost of these systems. The estimate is done by calculating the payback period based on the real costs of the devices available on the market and on the actual electricity cost. The result of the analysis shows that the payback period is lower than the lifespan of BACS devices, which is about 10 years. Therefore, BACS implementation is not only energy effective but also cost effective.