# Cumulative Energy Demand and Carbon Footprint of the Greenhouse Cultivation System
## 3 Results and Discussion
### Greenhouse Energy Performance  
The study revealed that the consumption of useful heat for heating purposes was 679.77 MWh.y\({}^{-1}\). The average seasonal total efficiency of the production, distribution and use of GH heat is 0.604 (expressed by Equation (2)). The final energy used to heat GH during the year, based on the total efficiency of the system, is 1125.04 MWh.y\({}^{-1}\) (from Equation (1)). The specific annual final energy consumption for the GH is 900 kWh.m\({}^{-2}\).y\({}^{-1}\). The structure of final energy consumption in individual months of the period under examination is presented, taking into account both heat and auxiliary electricity (Figure 2). The variability of final energy consumption depends on the external climate conditions, i.e., the outside temperature, the intensity of solar radiation and the length of the day. One can see that in the winter season, the final energy consumption is significantly higher than the consumption in the summer months. After determining the operation time of the GH heating system, its technical equipment, and the source of coal combustion heat, it was possible to calculate the consumption of auxiliary electricity at the level of 30.25 MWh.y\({}^{-1}\) (Table 4). \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Energy**} \\ \cline{2-4}  & \multicolumn{2}{c}{**kWh.y\({}^{-1}\)**} & \multicolumn{1}{c}{**\%**} \\ \hline  & drive of the thermal insulation screen & 46.8 & 0.15 \\  & drive of the vent servos & 33.0 & 0.11 \\ in the greenhouse & circulation pumps—the lower system & 1838.5 & 6.08 \\  & circulation pumps—the upper system & 4488.1 & 14.83 \\ \hline  & main circulation pumps at the heat source & 6652.3 & 21.99 \\  & boiler auxiliaries & 17,194.8 & 56.84 \\ \hline  & sum of auxiliary electricity & 30,253.4 & 100.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Structure of electricity consumption for driving motors in technical systems of the greenhouse (scenario 1). Figure 2: Monthly totals of final energy used for heating and auxiliary electricity used for the GH; fuel—coal (scenario 1). The structure of electricity consumption shown in Table 4 indicates that 79% of electricity is consumed in the heat source, and 21% is consumed directly in the greenhouse for the operation of technical systems. In scenarios other than the reference scenario, the electricity demand varies depending on the auxiliary equipment of the boiler. The demand for electricity production was determined according to the catalogue data of boilers used for scenarios 2-4; in scenario 2 it was 16.60 MWh\(\cdot\)y\({}^{-1}\), and in biomass-fired boilers, it was 22.12 MWh\(\cdot\)y\({}^{-1}\). In the current state, the annual specific consumption of auxiliary electricity in the GH is 24.2 kWh\(\cdot\)m\({}^{-2}\)\(\cdot\)y\({}^{-1}\), and in the natural gas scenario is 13.3 kWh\(\cdot\)m\({}^{-2}\)\(\cdot\)y\({}^{-1}\), i.e., 45.1% less than in scenario 1. The corresponding value for the biomass scenario is 17.7 kWh\(\cdot\)m\({}^{-2}\)\(\cdot\)y\({}^{-1}\), which is 73.1% compared to the reference scenario. Scenario 2 for gas boilers assumes an average annual heat generation efficiency of 0.860, which means that the total efficiency of heat generation, distribution and use would change to 0.728. The final energy for heating the GH over a year is 933.99 MWh\(\cdot\)y\({}^{-1}\), and the specific annual final energy consumption for the GH would be 747.23 kWh\(\cdot\)m\({}^{-2}\)\(\cdot\)y\({}^{-1}\). The difference in final energy consumption for heating amounts to 17%. The structure of monthly final energy consumption for the scenario with gas boilers is presented in a similar way to that for the current state (Figure 3). In scenarios 3 and 4 for biomass combustion, the average annual heat generation efficiency is 0.850, and the total system efficiency is 0.704. The final energy for heating is 966.21 MWh\(\cdot\)y\({}^{-1}\), which means that the annual specific final energy consumption is 773.0 kWh\(\cdot\)m\({}^{-2}\)\(\cdot\)y\({}^{-1}\).