## 3 The Case Study
### Technical Systems and Monitoring  
Due to the small volume of the MUZA and the high level of airtightness of the thermal envelope, it was necessary to install mechanical ventilation with heat recovery (MVHR) in order to ensure adequate indoor air quality. MVHR is realized by two units of a decentralized MVHR system, which, at the same time, allows for saving energy. The efficiency of the installed heat recovery system is 80%.  
The heating and cooling needs are met by a highly efficient air-to-water reversible heat pump (heating and cooling power 5 kW, \(COP\) up to 4.93 for +A7/W35, according to EN 14825). Heated or cooled indoor air is distributed by two fan coil units. One unit is located in the suspended ceiling directly above the technical room, while another unit is located on the wall (Figure 7).  
Three photovoltaic (PV) panels of total nominal power output 1.005 kW, are installed on the roof. Their inclination can be manually adapted in range from 15-45\({}^{\circ}\) (Figure 4). When the PV panels are inclined, they have the same orientation as the main facade. Therefore, PV's orientation is related to the position of the MUZA itself in a certain location. The idea was to use the electricity generated by the PVs only for the MUZA's ongoing needs (HVAC, lighting, mechanical ventilation, TV, tablets, sensors for monitoring, etc.), i.e., to be energy self-sufficient when outdoor conditions make it possible. Moreover, due to mobility requirements and related administration issues, it was not an option to release excess energy to the grid. Therefore, a smart inverter was chosen as the optimal solution. The smart inverter is actually \"smart\" thanks to a system-compatible component Energy Meter, which calculates phase-exact and balanced electrical measured values, and communicates these via Ethernet to the local network. In this way, all produced and used electricity can be communicated to the system frequently and with a high level of precision. In this way, no excess electricity is produced. When weather conditions are unfavourable, the required difference of electricity is taken from the grid.  
A real-time monitoring system is installed in order to understand how MUZA performs when used in real conditions and in different climates, where monitored parameters are the following: energy consumption, energy produced by PV panels, indoor air quality parameters (temperature, relative humidity, CO\({}_{2}\) concentration, relative indoor air quality), and hygrothermal performance of the external wall (temperature and relative humidity in all characteristic layers).  
The system measures energy consumption of the whole building, HVAC system, MVHR and ventilation system, and lighting. Energy consumption is measured using smart WiFi modules (power tags) that monitor and measure energy and power in real-time (current, voltage, power, power factor, energy) and wirelessly communicate these data via a gateway to the router. Power tags are installed on the classical automatic fuses. This home automation is controlled using a logical controller (gateway) installed in the main distribution cabinet. Monitoring is out of the scope of this paper, and the results will be analysed and published elsewhere.