Sustainable heating and cooling

Use water as energy carrier and source of ambient heat

About half of the energy consumed in the Netherlands is used for heating, so we can also speak of a heat transition. And in this heat transition water plays an important role thanks to its large thermal capacity. This thermal capacity makes it possible to extract heat (and cold) from water (aquathermal energy), and to use water in the ground to store heat (geothermal energy). Water’s large thermal capacity explains why about 80% of all energy consumption in the water cycle is used to heat tap water in homes and buildings. Energy savings in hot water use are therefore essential for energy savings in the water cycle.

Methods, tools and products

KWR disposes of various means of researching the role of water and water quality in the sustainable heating and cooling of buildings. For instance, we develop and build test set-ups for practical research, and we have extensive lab facilities for research into microbial and chemical water quality. We don’t always do this on our own: whenever necessary we also collaborate with knowledge partners at home and abroad. Furthermore, we have the knowledge to develop digital tools for the ‘energy and water’ field of work. KWR also supports digital tools that are managed by other parties, such as the aquathermal energy potential map.

Aquathermal energy: TEO, TEA and TED

Aquathermal energy (heat and cold from water) is a sustainable alternative for heating and cooling of buildings. Aquathermal energy is the collective name for thermal energy that can be obtained or recovered from water sources. A distinction is made between thermal energy from surface water (TEO in its Dutch abbreviation), from wastewater (TEA) and from drinking water (TED). Each category can be further subdivided into different types of sources. In the case of thermal energy from drinking water, for example, a distinction can be made between untreated water and clean water. Aquathermal energy is a ‘very low temperature heat source’ (10-30°C). This means that a heat pump is needed to bring this heat up to a usable temperature for space heating purposes. By applying aquathermal energy in combination with subsurface heat storage, heat extracted in the summer can be used in the winter as a replacement for fossil energy sources. KWR has calculated and mapped out the TED potential for most areas in the Netherlands; the result can be seen in the aquathermal energy viewer. KWR has also developed a Q&A for TED.

Subsurface heat and cold storag

The storage of heat and/or cold in the subsurface is the most (cost) efficient form of larger-scale thermal energy storage, and therefore constitutes an important link in the heat transition. We can for example store the surplus heat from geothermal, industrial residual-heat, solar or wind sources in the summer for later use in the winter. KWR researches and develops design criteria to energetically optimise this storage under different conditions, and also studies how the undesirable thermal effects can be avoided.

Hot tap water at low temperature

A low-temperature (LT) heating system presents energy advantages compared to a high-temperature system. For example, an LT heating system, when compared to conventional high-temperature heating, is subject to less heat loss during the distribution and circulation of heat and a heat pump performs more efficiently. When LT systems are used in the production of hot tap water, account needs to be taken of possible risks to public health, such as Legionella growth. The growth of legionella in a tap water system is a complex matter requiring specialist knowledge in both microbiology and installation construction. Whenever a conversion is made to a low-temperature tap water system, the climate neutrality of the chosen solution must also be considered so as to guarantee the Legionella safety. KWR has the knowledge and expertise to resolve this complex problem, and works in various projects with multiple partners at home and abroad on solutions to make low-temperature tap water safe, and thereby realise major energy savings.

Projects

Accelerating Energy Transition with Aquathermal Energy (EVA 2.0)
In the EVA2-project KWR joins the drinking water utilities in studying the effects of thermal energy from drinking water (TED) on the drinking water quality. This involved the development of a mobile test set-up which allows us to determine precisely the effect of a temperature rise on the growth of microorganisms in the drinking water. We also work in the project on the standardisation of TED systems. This project moreover facilitates the Water & Energy Network Group. In which experts in the field of energy and water from the drinking water sector participate.

 

WINDOW: Heat Provision in the Netherlands More Sustainable through Subsurface Heat Storage 
Heat storage contributes to reducing costs in the heat transition and ensures an optimal use of sustainable heat sources. Subsurface heat storage at high temperatures is only implemented to a very limited degree in the Netherlands. In the WINDOW-programma KWR and its partners developed knowledge to remove the technological, legal and business-case obstacles, so that subsurface heat storage can be implemented as a proven technology.

 

RELOaDH: Reduction of Energy LOss in Distribution and Heating of Hot water
In the RELOaDH-project KWR is conducting research with various partners into the possibility of safely lowering the temperature of hot tap water in utility buildings and residential towers, through the application of UV and filter technology (UF). This includes, among others, the use of practical research into the growth of Legionella in a test facility. An LCA approach is also being used to study the sustainability of UF and UV technologies, compared to a conventional system at higher temperature. The ultimate goal of the RELOaDH project is to contribute to standard renovation concepts for tap water in collective drinking water installations.