**3. Mathematical model of the cooling system**

The equations presented in this section describe briefly the main components used for the simulation; a detailed information could be found in [4].

#### **3.1 Assumptions**


#### **3.2 Basic equations**

The solar thermal collector efficiency (Type1b) was calculated using a quadratic or linear efficiency equation according to ASHRAE or European standards. The solar collector is an HTP-Evacuated Tube HP-30SC [5] with a net aperture area of 3.86 m2 . The solar thermal collector efficiency is presented in Eq. (1):

$$\eta = \textbf{0.418} - \textbf{1.17} \frac{\{T\_{IN} - T\_{ENV}\}}{Q\_{BAD}} \tag{1}$$

where TIN and TENV are the input temperatures of the solar collector and environment temperature, respectively, and QRAD is the global radiation incident (W/m2 °C).

The building (Type 56) is a simple multi-zone building with four windows and only one zone with some dimensions and main building characteristics are shown in **Table 3**. Four occupants in a rest position and three computers turned on from 08:00 to 18:00 were considered as heat generation [6].

The Type4a is a stratified storage tank. The properties and working conditions supplied were a heat capacity of 2.24 kJ/kg K for the heating fluid, an initial temperature of 70°C, and a loss coefficient = 0.75W/m2 K. The characteristics of

