Analysis of profitability of using a heat recovery system from grey water discharged from the shower (case study of Poland)

Abstract

Abstract. The paper analyses the profitability of the use of Drain Water Heat Recovery units. An original simulation model was used for this purpose, and a detached residential building located in Poland was selected as the test facility. The conducted analysis proved that the type of the hot water heater has decisive influence on the profitability level of such an investment. Application of the abovementioned technology is particularly profitable, when water is heated with the use of an electrical device. When the energy source in the system is a gas water heater, the obtained calculation results are not as favourable, and the period of investment return in many cases exceeds the expected service life of these devices. Moreover, the analysis demonstrated that the potential energy savings, and thus also the financial savings, may be in both cases increased as a result of simultaneous intake of water from various water taps.

An Analysis of the Effectiveness of Two Rainwater Harvesting Systems Located in Central Eastern Europe

“…The project will be accepted when NPV is greater than zero. The NPV value can be determined from formula (4).…”

“…Sustainable exploitation of natural resources and their protection is of key importance for smart development [1,2]. To achieve this, it is necessary to implement alternative sources of water and energy in all areas of the economy, especially in housing, which is characterized by a high demand for water and energy [3,4]. It is estimated that domestic use of freshwater is about 10% of the total global water demand [5].…”

Opportunities and Threats of Implementing Drain Water Heat Recovery Units in Poland

“…The price criterion is vital when selecting an energy source [40]. Expansion of these systems is also affected by the ability to gain financial benefits, which-as studies show [30] depend on a number of parameters related to the type of exchanger used and installation performance. Furthermore, the use of unconventional energy sources can also be supported by appropriate subsidies.…”

“…Moreover, in many cases, the supply of these devices on the market is not sufficient, which further impedes the expansion of drain heat recovery systems.The above problems also occur in Poland, consequently wastewater heat recovery systems are applied very rarely. There is also no detailed analysis of the rationality of using DWHR units in residential buildings, and the scope of the published papers is limited to financial analysis [30,31].In order to increase the degree of acceptance for heat recovery from drain water discharged from the shower, as well as the degree of their implementation in residential buildings, the article presents the strengths and weaknesses of such a solution. These factors are defined based on the computational fluid dynamics (CFD) model of the DWHR heat exchanger, which allows visualization of heat flow in the device.…”

“…The above problems also occur in Poland, consequently wastewater heat recovery systems are applied very rarely. There is also no detailed analysis of the rationality of using DWHR units in residential buildings, and the scope of the published papers is limited to financial analysis [30,31].…”