## 6 Discussion
In addition, for CHPPs 2 and 5 slack movement is not observed on any indicator. For the rest of the CHPPs such changes are present. In this experiment, it can be seen that the efficiency coefficients are significantly higher for the same sample as in previous experiments. Additionally, there are significantly more efficient enterprises. In comparison with the previous experiment, where CHPPs 3 and 6 had a rather low efficiency of CRSTE and VRSTE (below 0.6), CHPP 3 is now an efficient enterprise. CHPP 6 has CRSTE and VRSTE performance indicators of more than 0.9. Accordingly, the introduction of another output, which the model focuses on, yielded a significant change in the performance indicators for the sample. In this case, with the introduction of the emission mass output, there was a significant increase in efficiency indicators. This may indicate that enterprises in the field of environmental factors are working quite efficiently. However, in the absence of this output, the same enterprises have lower performance indicators. All these features should be considered when compiling the algorithm of the DSS, adding possible options for changing the goal when solving the problem of increasing efficiency by the DEA method. In experiment 6, the input of the available thermal power of the equipment was replaced by three inputs: the heating power of turbo generators, the power of peak hot water boilers, and the power of steam boilers. This was done in order to be able to adjust the efficiency of work for each type of equipment used at the CHPP. In this experiment, the goal was to reduce the power of the equipment and the consumption of conventional fuel for the released fuel cell. Accordingly, the DEA model with four inputs and one output, oriented to the input, was used. As input indicators, the following were used: the heating capacity of turbo generators, the power of peak hot water boilers, the power of steam boilers, and the consumption of conventional fuel for the released fuel cell. As an output indicator, we used the heat energy released to the grid. This combination of inputs and outputs helped adjust the efficiency of each type of equipment, adjusting fuel consumption when achieving maximum efficiency of the CHPP. As a result of efficiency calculations using the DEA method for CCR and BCC models, the following data were obtained. In this experiment, with the same sample, only CHPP 2 is an effective enterprise according to the performance indicators of CRSTE, VRSTE, and SE. That is, CHPP 2 achieves maximum efficiency in operation. In addition, in this experiment, 5 enterprises are effective according to VRSTE: CHPPs 1, 2, 3, 4, and 6, having an efficiency score of 1. However, for four of them (CHPPs 1, 3, 4, and 6), there is slack movement. Only for CHPP 2 do the input indicators not change, while slack movement is also not observed for any indicator. For the rest of the CHPPs, such changes are present. The efficiency indicators for CHPP 1, 3, 4, and 6 are equal to 1. However, the efficiency indicators of CRSTE and SE are below 1. This suggests that these enterprises are working quite efficiently. The inefficiency of these enterprises is wholly caused by unfavorable conditions. They have a particularly strong effect on CHPP 3 and CHPP 6, since their SE is 0.627 and 0.582, respectively. In this experiment, it can be seen that the efficiency coefficients for VRSTE are significantly higher for the same sample as in previous experiments. For five CHPPs, these are 1, but only one CHPP, number 2, achieves maximum efficiency in operation. If in previous experiments CHPP 5 was effective and achieved maximum efficiency in operation, then in this experiment it is the only CHPP that has a VRSTE efficiency coefficient below 1. In this experiment, five CHPPs are at the point of increasing scale effect (increasing return to scale). Meanwhile, in experiments 3 and 4 only CHPPs 3 and 5 were at the point of increasing scale effect (increasing return to scale). Now, let us compare the data from experiment 3 and this experiment.