**2. Description of the Experimental Setup**

The SENS i-Lab is a multi-sensorial laboratory of the Department of Architecture and Industrial Design of the University of Campania Luigi Vanvitelli (Aversa, southern Italy, longitude: 14◦12 26 E, latitude: 40◦58 21 N). The SENS i-Lab consists of a human-centered, multi-physical, and multi-purpose test room served by an HVAC system, including a single duct dual-fan constant air volume (CAV) air handling unit, controlling indoor air temperature, indoor air relative humidity, indoor air velocity, and indoor air quality. The test room has a floor area of 16.0 m2 (its height is 3.6 m) and four vertical walls (without windows and one door); both the ceiling and floor are horizontal. It is installed inside the Department, so that its indoor conditions are not directly affected by external climatic conditions. Table A1 in Appendix A describes the material, thickness, thermal conductivity, conductive thermal resistance of each layer composing the walls, the ceiling, and the floor of the integrated test room.

A CAV AHU is commonly used in buildings; it is more common in existing old buildings or small new buildings, while in new medium/large buildings variable air volume (VAV) AHUs are the common choice of installation. In the case of CAV AHUs, volumetric flow rate of supply air is constant, while its supply temperature and relative humidity are varying. With respect to VAV AHUs, CAV AHUs are easier, cheaper, and quicker to install, but they are less efficient and with higher lifetime running costs. The AHU of the SENS i-Lab consists of these main functional subcomponents: return air fan (RAF); supply air fan (SAF); pre-heating coil (PreHC); post-heating coil (PostHC); cooling coil (CC); steam humidifier (HUM); static cross-flow heat recovery system (HRS); vapor compression air-to-water single-stage electric refrigerating system (RS) connected with the cooling coil; vapor-compression air-to-water single-stage electric heat pump (HP) connected with the pre-heating coil and the post-heating coil; valves (VPreHC, VPostHC, VCC, VHUM) controlling the flow rate of heat carrier fluid entering, respectively, the preheating coil, the post-heating coil, the cooling coil and the steam humidifier; return air damper (DRA); outside air damper (DOA); exhaust air damper (DEA); damper of the HRS (DHRS); return air filter (RAFil); outside air filter (OAFil); supply air filter (SAFil). Two 0.08 × 0.18 cm<sup>2</sup> air grilles are mounted on the south-oriented wall at floor level and two 0.08 × 0.18 cm2 air grilles are mounted on the north-oriented wall at floor level with the aim of extracting air from indoor space to be moved into the AHU; a 0.60 × 0.60 cm<sup>2</sup> swirl diffuser acting as supply air grille is mounted on the ceiling of the test room. Figure 1 reports the scheme of the AHU together with its main components.

**Figure 1.** Air handling unit scheme.

Figure A1 of Appendix A shows the floor plan of the test room including the AHU, together with the refrigerating system (RS), the heat pump (HP), as well as the return and supply air ducts. Table 1 indicates the characteristics of the functional components of the HVAC serving the SENS i-Lab. The system fulfills the requirements prescribed by the Ecodesign Directive 1253/2014 [34] introduced by the European Union in order to support the diffusion of energy efficient AHUs. The HVAC unit is equipped with a number of sensors to observe and register the key operating system parameters. The measuring range as well as the accuracy of the sensors are showed in Table 2.

The AHU is operated according to a specific control logic. In particular, the following parameters are manually set (and eventually modified during the test) by the end users: (i) the desired targets of both indoor relative humidity (RHSP,Room) and indoor air temperature (TSP,Room) to be reached and maintained into the test room; (ii) the deadband DBT for TSP,Room and the deadband DBRH for RHSP,Room; (iii) air flow rate of both the supply air fan (OLSAF) and the return air fan (OLRAF); (iv) opening percentages of the outside air damper (OPDOA), the return air damper (OPDRA), and the exhaust air damper (OPDEA); and (v) activation of the heat recovery system damper (OPDHRS). Flow rate of air moved by the supply air fan can range between 0 (OLSAF = 0%) and 1080 m3/h (OLSAF = 100%), while flow rate of air moved by the return air fan is between 0 (OLRAF = 0%) and 1460 m3/h (OLRAF = 100%); the maximum electric consumption of the SAF and RAF are, respectively, 1.22 kW and 0.48 kW. The parameter OPDHRS can be fixed at 100% (no heat recovery) or 0% (heat recovery takes place). The variation range of the parameters OPDRA, OPDOA, and OPDEA is 0 ÷ 100% (100% corresponds to the dampers fully open). Once the previous parameters are manually set by the end-users, opening percentages of the valves (OPV\_PreHC, OPV\_PostHC, OPV\_CC and OPV\_HUM) are automatically managed in the range 0 ÷ 100% by proportional-integral-derivative (PID) controllers in order to achieve the indoor desired targets. Opening percentages of the valves are continuously regulated between 0% and 100% as a function of differences between the targets of air temperature and relative humidity into the test room and their current values. In more detail, volumetric flow rate of fluid streaming inside the coils can be modulated between 0 and 0.860 m3/h, while flow rate of steam mass of the steam humidifier can be varied from 0 up to 5 kg/h.


#### **Table 1.** Main AHU components' characteristics.

**Table 2.** Measuring range and the accuracy of the AHU sensors.


Table 3 reports the main criteria for activating and deactivating the main functional subsystems of the AHU serving the test room. The pre-heating coil is not included in the table because this subsystem has been kept deactivated during the entire duration of all experimental tests. The post-heating coil is activated when return air temperature becomes not larger than the temperature difference (TSP,Room − DBT), while it is deactivated in the case of TRA assumes a value not lower than the temperature (TSP,Room + DBT). The cooling coil is activated when return air temperature becomes not lower than the temperature (TSP,Room + DBT), while it is deactivated in the case of TRA assumes a value not larger than the temperature difference (TSP,Room − DBT). The steam humidifier is activated when return air relative humidity becomes not larger than the air relative humidity difference (RHSP,Room − DBRH), while it is deactivated in the case of RHRA assumes a value not lower than the air relative humidity (RHSP,Room + DBRH). The heat pump is activated when temperature into the hot tank THT is lower than 44 ◦C, while it is deactivated in the case of THT assumes a value not lower than 46 ◦C. The refrigerating device is activated when the temperature into the cold tank TCT is larger than 8 ◦C, while it is deactivated in the case that TCT assumes a value not larger than 6 ◦C. The signals managing the opening percentages of the valves (OPV\_PreHC, OPV\_PostHC, OPV\_CC, and OPV\_HUM) are generated by PID controllers. As an alternative to the automatic operation based on PID controllers, the opening percentages of the valves (OPV\_PreHC, OPV\_PostHC, OPV\_CC, and OPV\_HUM) can be also forced by the end-users; therefore, the end user is allowed to force component operation/parameters based on specific research purposes.



However, alternatively, the end users can also manually force (at the beginning or during the test) the opening percentages of the valves for research purposes (instead of operating according to the automatic control logic).
