The Planning and implementation of construction projects are difficult processes and are burdened with many risk elements. The budget spread over time, which is developed on the basis of the schedule, presents the expected distribution of costs throughout the duration of the works, which during the implementation of the project is subject to constant changes resulting from time, cost, and organizational factors. Managing construction contracts requires managers to be able to analyze on an ongoing basis the variances of production costs-from the values calculated in the offer cost estimate and assumed in the Budgeted Cost of Work Scheduled. The article attempts to analyze the emerging time and cost deviations using proprietary time variances from the schedule (T/S) and variances from planned costs (T/C) monitoring, based on simple indicators of the earned value method (EVM). An example of construction of a multi-family housing development was used to study the variances of planned and incurred costs.

A prerequisite for achieving high energy efficiency of water supply systems (understood as using less energy to perform the same task) is the appropriate selection of all elements and their rational use. Energy consumption in water supply systems (WSS) is closely connected with water demand. Especially in the case of oversized water supply systems for which consumers’ water demand is at least 50% less than previously planned and flow velocity in some parts of the system is below 0.01 m·s⁻¹, this problem of excessive energy consumption can be observed. In the literature, it is difficult to find descriptions and methods of energy management for such a case. The purpose of this study was both an evaluation of the current demand of an oversized WSS and a preliminary technical analysis of the possibility for energy saving. Solutions are presented that resulted in improvements in energy management, thus increasing energy efficiency. The conducted analyses indicate the wide use of numerical, hydraulic models, among others, for the needs of the sustainable oversize water supply systems management in order to improve energy efficiency. Those simulations only give energy consumption results as a first step in the process of decision-making for the modernization process, in which investment costs should be taken into account as a second step. Thus, this paper emphasizes the crucial role of hydraulic models as a good analytical tool used in decision support systems (DSS), especially for large, oversized water supply systems.

Water management in cities is a critical factor for sustainable growth and development. Satisfying the current needs with respect for the future is not possible without properly managed water and wastewater systems. An essential element of wastewater systems is the wastewater treatment plant (WWTP). The nexus between wastewater treatments and energy demand is a well-known problem. In times of energy crisis, effective energy management in this critical infrastructure is a key task. The purpose of this article is to analyze WWTPs’ energy consumption with regard to proposed management strategies for managers, designers and decision makers. A detailed analysis of WWTP operational parameters and a proposal of improvement actions will be useful for applicability and benchmarking studies. Estimating the carbon footprint (CF) of selected WWTPs considering the indirect emissions due to energy consumption is an important step for developing energy neutrality of WWTPs. Due to the desire to deepen research in the area of a complex phenomenon, which is the energy management system in WWTPs, the research undertaken herein is based on the case study method of three water and sewage companies operating southwestern Poland. Each urban area has different specificities, natural conditions and needs. The presented results of the analyses may be the basis for developing directions for changes in national policy, other benchmarking studies, and improving the energy management system in WWTPs.

Planning and implementation of construction projects are difficult processes and are burdened with many risk elements. The budget spread over time, which is developed on the basis of the schedule, presents the expected distribution of costs throughout the duration of the works, which during the implementation of the project is subject to constant changes resulting from time, cost and organizational factors. Managing construction contracts requires managers to be able to analyze on an ongoing basis the variances of production costs - from the values calculated in the offer cost estimate and assumed in the Budgeted Cost of Work Scheduled. The article attempts to analyze the emerging time and cost variances using proprietary C-S and S-C monitoring, based on simple indicators of the EVM method. An example of construction of a multi-family housing development was used to study the variances of planned and incurred costs.