*2.2. Building Description*

The case study of this work is the Rectorate building of the University of the Basque Country (Spain) constructed in the 1970s. It is a large building divided in three blocks (west, central and east), as shown in Figure 1. For the purpose of this work, only the west block was considered, which is an office building that includes a nursery. Four storeys form the block: floor 0 (Ground Floor) and Floor 2 (2F) consist of rooms and offices while Floor 1 (1F) and Floor 3 (3F) are mainly open spaces (see Figure 2). As the building use is office work, the occupation takes place only during weekdays, being reduced during summer. There is lighting consumption from 7 a.m. to 8 p.m., except on the second floor, where lighting consumption ends at 6 p.m. The building has a centralised heating system with hot water radiators powered by a campus district heating. The heating works the whole year following a control program according to a schedule from 6 a.m. to 7 p.m. except in July and August, when the heating remains off. A refurbishment of the building was made in the summer of 2016 on the ground floor and in the summer of 2017 in the rest of the building to reduce its energy consumption.

**Figure 1.** (**a**) View of the whole rectorate building that is formed by three blocks (west, central and east). This work focussed in the study of the retrofitting measures carried out in the west block. (**b**) West block before retrofitting. (**c**) West block after retrofitting.

### 2.2.1. Building Description before Retrofitting

Before the retrofitting, the building did not have any insulation. Most of the façade was built with precast reinforced concrete panels with non-ventilated air gap. Regarding the windows, some were single-glazed with wooden frame, and others were double-glazed but with aluminium frame without thermal break. Before retrofitting, there was no air conditioning or mechanical ventilation system.

### 2.2.2. Building Description after Retrofitting

The refurbishment consisted in several measures to improve the building's envelope and energy system. The façade was insulated with vacuum insulated panels (VIPs) to reduce heat losses through the envelope. Some windows were replaced by high-performance windows. To improve the lighting consumption of the building, LED lighting was installed. A ventilation system with heat recovery was added on each floor. Furthermore, thermostatic valves were installed to improve the control of the hot water radiators. A detailed description of the refurbishment and an assessment of the heat loss coefficient of the building is provided in [20].

**Figure 2.** Plans of the four floors in the west block of the building with their space distribution and dimensions. The use of each space is represented with colours: offices (brown), nursery (green), storage rooms (grey), corridors (pink) and server room (blue). In addition, the distribution of the sensors is also displayed: circles, illuminance, temperature and relative humidity; triangles, calorimeters; and square, lighting consumption.

### 2.2.3. Monitoring Description of the Building

The monitoring started before the refurbishment to investigate the necessary energy conservation measures. Thus, monitored data before and after retrofitting from sensors located all around the building are available. Monitored data before retrofitting correspond to 2016 and 2017, and data after retrofitting correspond to s 2018 and 2019; all data are minute-by-minute values. In particular, on the ground floor, the renovation started a year earlier with the insulation of a false ceiling and the installation of LED lighting. In this case, the years considered before retrofitting are 2015 and 2016. The monitored variables include outdoors conditions, indoors conditions and building heating and lighting consumption. Table 1 presents all the monitored variables in the building used to assess the impact that the retrofitting had on the building's energy performance, comfort and lighting. Indoor condition sensors are located in several points at each floor, as shown in Figure 2. The electrical consumption and the heating demand is provided per floor. Further information about the monitoring of the building can be found in the work carried out by Erkoreka et al. [69].
