Abstract
The energy needed for domestic hot water represents an important share in the total energy use of well-insulated and airtight buildings. One of the main reasons for this high energy demand is that hot water is produced at temperatures above 60°C to mitigate the risk of contaminating the hot water system with Legionella pneumophila. However, this elevated temperature is not necessary for most domestic hot water applications, and has a negative effect on the efficiency of hot water production units. A simulation model has been developed which proposes an alternative to this constant 60°C by predicting the Legionella pneumophila concentration dynamically throughout the hot water system. Based on this knowledge, a hot water controller is added to the simulation model that sets a lower hot water comfort temperature in combination with heat shocks. In this paper, the simulation model is used to estimate the energy saving potential in a case study building, at the level of the heat production system by reaching higher production efficiencies. Three different production units, namely an electric boiler, heat pump and solar collector have been investigated. The controller is expected to become an alternative for the current, energy intensive, high temperature tap water heating systems.
Highlights
Introduction1.1 MotivationThe energy needed for production, storage and distribution of Domestic Hot Water (DHW) represents an important share in the total energy use of well-insulated and airtight buildings
The energy needed for production, storage and distribution of Domestic Hot Water (DHW) represents an important share in the total energy use of well-insulated and airtight buildings
One of the main reasons for this high energy demand is that hot water is produced, stored and distributed at temperatures above 60°C to mitigate the risk of contaminating the hot water system with Legionella pneumophila, a bacteria that can cause an acute respiratory disease or severe pneumonia which can be fatal
Summary
1.1 MotivationThe energy needed for production, storage and distribution of Domestic Hot Water (DHW) represents an important share in the total energy use of well-insulated and airtight buildings. A simulation model has been developed that proposes an alternative to this constant 60°C by predicting the Legionella pneumophila concentration dynamically throughout the hot water system as this concentration cannot be measured in real time [1] Based on this knowledge, a hot water controller is added to the simulation model that sets a lower hot water comfort temperature in combination with heat shocks when a predefined concentration limit has been reached in simulation. A hot water controller is added to the simulation model that sets a lower hot water comfort temperature in combination with heat shocks when a predefined concentration limit has been reached in simulation Simulation results of such a controller show savings of more than 35% on the hot water distribution energy use in an apartment building, without increasing contamination risk [2].
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