Decentralized systems
Clear advantages for drinking water hygiene and energy consumption
Designing an efficient, sustainable, and hygienic hot water supply
Regardless of whether it is an apartment, a single-family house or a residential complex: Residents expect a reliable supply of heating and, depending on the country, cooling, as well as hot and cold water of the highest drinking water quality. Until the energy crisis, it didn't matter to many users how the heat was generated or how the hot water was heated. Until 2022, energy was a negligible cost factor: the average electricity price per kWh in Europe was around 30 % lower in 2013 1 compared to mid-2023 and the price of gas has risen rapidly since 2021. In addition to the higher costs for the energy supply of properties and rental apartments, discussions on climate change and resource conservation have prompted end consumers to rethink their approach to energy. In addition, legislation as part of the “European Green Deal” is creating increased demand for efficient and therefore cost-effective energy supply solutions for buildings. Not only commercial property developers, but also private building owners are increasingly looking at suitable options - both on the technical side and in terms of subsidies that have been introduced as part of energy saving legislation. As a result, the decision on the right solution for the energy-efficient supply of heat, conditioned air and hot water no longer lies solely with the planner or installer. However, it is not always easy to find your way through the jungle of energy-efficient solutions on offer and find the right system for a new build or renovation project.
Drinking water quality top priority
It is not only energy-saving aspects that should play a role in water heating in particular. Factors such as short response times when providing hot water and the associated convenience as well as the absolute hygiene of water, which is food, a resource worth protecting and a source of regeneration and relaxation at the same time, are no less important. It is important to comply with the drinking water regulations of the legislator and to pay attention to the health of users: In 2021, 2.4 cases of legionella per 100,000 households were registered in the EU/EEA; 75% of these occurred in Spain, Italy, France and Germany. This makes it all the more important to take a close look at the advantages and disadvantages of the technical solutions for the individual application - for a safe and sustainable hot water supply.Centralized or decentralized hot water supply
The most common hot water supply concepts are centralized or decentralized systems. Both solutions have their justification and should be weighed up as an option based on their respective advantages and disadvantages, with arguments being made at all levels, from the planning phase for a project to installation and the pros and cons for the end user. The advantages of centralized water heating lie in the variety of energy forms with which the water is usually heated via the heating system. These range from oil, gas, wood and pellets to solar energy, geothermal energy and heat pumps. With the introduction of central heating, which established itself as a standard system in house construction from the 1970s onwards, hot water preparation was generally linked to the central heating system.The disadvantages of the centralized solution can be divided into the two major areas costs and hygiene: storage and pipe losses, distribution via the building by pump and hot water circulation result in higher overall energy consumption. In addition, long pipe runs result in unnecessary costs for fresh water, because if hot water is not immediately available, cold water has to run through the tap or shower first, sometimes for several minutes. This not only increases consumption costs, but is also an unnecessary waste of the valuable resource of fresh water. In addition, the water tank of the heating system requires a lot of space - with rising construction costs per cubic meter of enclosed space, the basement or extra space for the water tank becomes a real cost factor. And finally, there is a greater risk of germs forming in central hot water systems, as the stagnation of hot water in the central pipe network makes it particularly easy for legionella to multiply. The legal obligation to inspect a centralized system results in additional costs and time.2
1 Source: Strompreise in Europa: Was Strom in der EU kostet (strom-report.com)
2 Only relevant for Germany
Advantages of decentralized concepts
With so-called heat interface units, the water is heated as required - in other words, using the instantaneous principle. Modern flat stations perform this function at a central location in the home, so that all taps are supplied with hot water from there. On-demand hot water supply ensures a minimum amount of water in the system, which leads to less stagnation. There is also “no warming through” from the circulation pipe to the cold water pipe, which means that cold water stays cold. Due to the small amount of water in the system, it is easy to ensure a complete water exchange several times a day during normal use. These are all important prerequisites for hygienic water supply and remove the breeding ground for germs and legionella. Extremely fast reaction times, combined with the fact that the water no longer has to be transported to the consumer via long pipes, ensure that heated water comes out of the shower or tap immediately. A convenience that contributes significantly to the quality of living and well-being. Last but not least, it reduces costs, because heating water only as required reduces the energy required to keep hot water available; pumps can be saved as there is no need for circulation. This is easy on the investment budget and reduces operating costs in equal measure.
Decentralized water heating & heating and cooling supply from Uponor
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Public relations
Beatrix Pfundstein
Senior Specialist Public Relations
GF Building Flow Solutions