## 3 Results and Discussion
### EAHX Room Load Removal: Assessing Standardone EAHX Cooling and EAHX Design  
This section presents results for room comfort expectancy level III (Category III), which, according to the results of the previous section, allows for room cooling with the most demanding outdoor air design condition (37 \({}^{\circ}\)C), specified in ASHRAE [38]. From EAHX temperature gradients and EAHX airflow rate data, EAHX load removal was determined using Equations (1) and (2). Figure 9 highlights, for the room occupancy period between 8 and 18 h, hourly statistics of specific values (and absolute values) of EAHX room load removal \(\dot{q}_{\text{rIII}}^{\text{EAHX}}\) (\(\dot{Q}_{\text{rIII}}^{\text{EAHX}}\)) and of EAHX outdoor air load removal, \(\dot{q}_{\text{oa}}^{\text{EAHX}}\) (\(\dot{Q}_{\text{oa}}^{\text{EAHX}}\)). Figure 8: Various EAHX temperature gradients as a function of outdoor air temperature and trendline for \(\Delta T_{\text{a0,rs}}\). Obtained from monitored data (between 1 June and 30 September; cooling mode only, \(T_{\text{aL}}<T_{\text{a0}}\): 8000 m\({}^{3}\)/h nominal airflow rate). Left axis applies to \(|\Delta T_{\text{aL,a0}}|\), \(\Delta T_{\text{a0,rsIII}}\) and \(\Delta T_{\text{aL,rIII}}\): right axis applies to \(\Delta T_{\text{a0,rsI}}\) and \(\Delta T_{\text{aL,rIs}}\). As mentioned in Section 2.3 and confirmed in Figure 9, EAHX room load removal is larger during the morning, region B (the result of the added outdoor air free-cooling component, \(Q_{\rm r}^{\rm QA}\)), whilst EAHX outdoor air load removal is larger during the afternoon, region C (the result of the added component \(Q_{\rm n}^{\rm EAHX}\)). Figure 9 presents large absolute outdoor air load removal (\(|Q_{\rm oa}^{\rm EAHX}|\)) during afternoons, with medians and maxima exceeding 13.5 kW and 27 kW, respectively. As regards specific room load removal (\(|q_{\rm rfill}^{\rm EAHX}|\)), from Figure 9 it is concluded that median values of this performance index are always higher than 20 W/m\({}^{2}\), the room _design_ (or peak) cooling demand (recall Section 2.1). However, during the afternoon, when summer outdoor conditions are more demanding and when the design outdoor air temperature typically applies [38], interquartile ranges for \(|q_{\rm rfill}^{\rm EAHX}|\) are very wide, extending from \(\sim\)0 W/m\({}^{2}\) (\(Q_{1}\)) to above 50 W/m\({}^{2}\) (\(Q_{3}\)). It is, hence, important to assess in more detail the actual EAHX room load removal for hot afternoons. Using monitoring data, Figure 10 presents the following conditional probability distributions, \(P\)(\(|q_{\rm rfill}^{\rm EAHX}|\geq q_{\rm rf}^{\rm BLDG}|T_{\rm a0}=T\)) with \(q_{\rm rf}^{\rm BLDG}\in\mathbb{R}\) and \(T\in\{33\,^{\circ}\mathrm{C},35\,^{\circ}\mathrm{C},37\,^{\circ}\mathrm{C}\}\), i.e., the probability that the EAHX delivers a specific (room) cooling capacity greater or equal to the specific room cooling demand, \(q_{\rm rf}^{\rm BLDG}\), conditional to outdoor air temperature being equal to Beja's 2%, 1% or 0.4% design dry-bulb outdoor air temperatures [38]. Figure 10 shows that for Beja's 2% design dry-bulb outdoor air temperature (\(T_{\rm a0}=33\,^{\circ}\mathrm{C}\)), the probability that the EAHX meets the 20 W/m\({}^{2}\) room peak cooling demand is 84%. Therefore, considering this (less demanding) outdoor air temperature design criterion, standalone use of the built EAHX for office room cooling is accepted. For the 1% design dry-bulb outdoor air temperature (\(T_{\rm a0}=35\,^{\circ}\mathrm{C}\)), the probability that the EAHX meets the 20 W/m\({}^{2}\) room peak cooling demand reduces to 45%, and for the most demanding 0.4% design criterion, this probability is less than 5%. For these moderate and more demanding criteria (\(T_{\rm a0}\geq 35\,^{\circ}\mathrm{C}\)), it is concluded that standalone use of the built EAHX does not provide sufficient cooling and does not warrant room temperatures below the upper setpoint.