## 2 Materials and Methods
The reason is that although the temperature is much lower in frozen storage, in this case products are introduced directly frozen do not imply respiration rates and the intake of fresh air is eliminated. The study was conducted for a 50% load of vegetables and fruits and a 50% load of meat respectively, in the refrigerated storage. The average heat of respiration for vegetables and fruits was 100 mW/kg product [11] and the Air Change Factor (ACF) was 4 (storage room/24 h), [16]. Under these conditions, by using Coolpack Software, Version 1.5 [20], the following percentage data on the components of the cooling load resulted: \(10\div 15\%\) transmission loads, \(10\div 20\%\) infiltration loads, \(47\div 52\%\) products and other loads (including heat of respiration) \(13\div 33\%\). Figures 2 and 3 show that the refrigerating load required to cool the storage spaces decrease with the increase in the insulating layer thickness. The transmission heat transfer  
Figure 3: Total cooling load required for frozen storage. Figure 2: Total cooling load required for refrigeration. dictates the cooling power decreasing trend. The cooling capacity is delivered by a vapor compression system with an air-cooled condenser. The total amount of energy consumption for cold/frozen storage is calculated by using the following Equation (3). \[\mathrm{P_{el}}=\frac{\mathrm{\dot{Q}_{E}}}{\mathrm{EER}}\ [\mathrm{kW}] \tag{3}\]  
where:  
\(\mathrm{\dot{Q}_{E}}\)--total cooling load [kW]; EER--Refrigeration system's Energy Efficiency Ratio [-]. The coefficient EER used in calculations is assumed to be 2.8 \(\div\) 3.3 for the refrigeration system in the cold storage as a function of the outside temperature climatic zone and 2 for frozen storage. The reason for the fact that in the first case the value is found around a certain interval is that it depends on the outside temperature, and implicitly on the climatic zone. Instead, in the second situation, the cooling system used is a Booster refrigeration system type that is not influenced by the outside temperature and that is why we assumed a fixed value. The input data for EER calculations are presented in Table 3.  
The total of the operating hours for the refrigeration system is 20 h/day, 365 days/year corresponding to 10 years lifetime as we considered that for an interval of 4 h daily the products are introduced or extracted from the cold storage and during that time the refrigeration system does not work. By using the CoolPack Software [20], the authors simulated the real thermodynamic cycles for each climatic zone working using the input data given by Table 3.  
The electricity cost value available for a day interval between Monday to Friday is given in \[\dot{\mathrm{Q}}\ =\mathrm{U}\cdot\mathrm{A}\cdot\mathrm{\Delta T}\ [\mathrm{W}] \tag{1}\]0 For weekend the price is fixed at 0.033 EUR/kWh [21; 22]. The cost of a sandwich panel per unit surface was taken from the price list of the main distributors from the Romanian market and it corresponds to the summer of 2021, and it is presented in Table 5, [23; 24]. The annual net energy saving amount for cold/frozen storage when using insulation different to OIT can be calculated as:  
\[\dot{\mathrm{Q}}\ =\mathrm{U}\cdot\mathrm{A}\cdot\mathrm{\Delta T}\ [\mathrm{W}] \tag{1}\]1 \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Climatic Zone** & **Constanta** & **Bucharest** & **Cluj Napoca** & **Brasov** & **Miercurea Ciuc** \\ \hline Cost & & & & & \\ (Eur/kWh) & 0.097 & 0.093 & 0.092 & 0.105 & 0.105 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Electricity cost. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Insulation Thickness [m]** & 0.03 & 0.04 & 0.05 & 0.06 & 0.08 & 0.1 & 0.12 & 0.15 & 0.18 & 0.2 \\ \hline
**Cost (Eur/m\({}^{2}\))** & 12.53 & 13.2 & 14 & 15 & 17.16 & 18.63 & 20.42 & 24.8 & 35 & 42 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Insulation costs.