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Legionella safe & energy efficient domestic hot water with limited water volume

Energy optimization is central for sustainable development and domestic hot water temperature is important. A compromise between energy use and microbial safety is needed. The limited water volume solution allows water temperature to be reduced without increasing Legionella risk.

Aim and goal

This project aims at evaluating how a limited domestic hot water (DHW) volume at reduced temperature will affect the growth of Legionella and how such a system could be implemented in real buildings.

Challenge

One important aspect in sustainable building is to optimize energy consumption, with DHW temperature being one essential factor. The optimal DHW temperature is often a balance between energy demands and microbial safety, in particular the risk of Legionella spp. at temperatures below 50 °C. Methods to remove Legionella used today has been shown to last for a short time and give rise to e.g. problems with leakage due to damage on the DHW installations. There is therefore a need to investigate novel approaches to solve this problem.

Solution

In new building constructions and renewal projects it is important to design the DHW system correct to minimize energy consumption and lower the risk of Legionella. One such approach would be to use a small volume of DHW, e.g. 3 L, and to heat the water instantaneously when needed. This approach has been tested in Germany and Denmark, but further evaluations are needed under Swedish conditions. There is also a need to study the Legionella biofilm formation under controlled conditions in such a system to be able to assess the risks in a long-term perspective.

Effect

The investigated system could potentially provide a stronger Legionella protection, and simultaneously allow a reduction of the DHW temperature with substantial reduction in the energy consumption.

Summary

Project name

Legionella safe domestic hot water

Status

Completed

RISE role in project

Project manager

Project start

Duration

2016-2020

Partner

Lund University, 19 partners representing technology suppliers, energy companies, consultants

Funders

Formas, Project information in Formas project database

Project members

Events

Supports the UN sustainability goals

3. Good health and well-being
6. Clean water and sanitation
9. Industry, innovation and infrastructure
11. Sustainable cities and communities
Charlotta Löfström

Contact person

Charlotta Löfström

Senior forskare

Read more about Charlotta

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