greenWATERrecycling – utilization of greywater for energy recovery and for providing greywater-filtrate for watering green walls

Development of a system for energy-recovery of waste heat of greywater and of greywater-filtrate in ordert o reduce the energy consumption of hot water supply and the water consumption for irrigation.

Short Description



Starting point / motivation

Steady progress is taking place due to significant research as well as the collection of long-term experience in the field of thermal insulation of buildings, recovery of ventilation heat losses and energy efficiency of electrical applications.

Hot water supply accounts for the most essential proportion within the total energy consumption in buildings, according to today's construction standard, causing this to stand out blatantly in comparison to the lack of utilization of the waste heat from the hot water treatment. This combination of sewage and irrigation needs of building or green façade, represents an innovative coupling of energetic optimizations and small-climatic improvements.

The energy consumption for hot water treatment represents the greatest potential for increasing efficiency in the building sector, nowadays. Building and urban greening leads to the improvement of the urban microclimate, but the need for irrigation for water supply means that bottlenecks in the water supply are to be expected, especially in dry seasons. Therefore, the research project picks up these two aspects and combines them into a profitable overall solution.

Contents and goals

The aim of this project is to design a technically proven solution for the material and thermal recovery of greywater, on the one hand, to be able to use the resulting filtrate for irrigation purposes whilst, on the other hand, pioneering in the idea of recovering waste heat.

As a result, drinking water shortages, which can be expected in dry summer months due to climate change, can be mitigated, while at the same time irrigating essential green islands ensuring the reduction urban heat islands. Through thermal recovery, a part of the energy for domestic water heating can be saved. The approach of such an efficient utilization of greywater, both materially and thermally, is unique and novel.

One of the focal points of the project is the efficient recovery of waste heat with minimum heat loss. Housing developments of different sizes as well as housing-like uses, which have more or less seasonally constant greywater volumes, are considered in order to ensure the cost-effectiveness of the overall solution.


The project covers planning and technical aspects. At the same time, according to the holistic concept, the requirements of the system are also considered. Therefore, investigations are carried out on the quality of greywater after the cleaning and filtration process and its compatibility with plants of relevance to urban greening. In addition, further applications within buildings and the potential complications associated with the use of greywater are being investigated.

In addition to the conceptual considerations, a prototype of the plant will be built and subjected to various experiments within the framework of the project. This should ensure the long-lasting functionality and a high market relevance.

Expected results

A prototype of the system will be installed and tested. Following the required detailed investigation concerning the design and regulation of the technical test facility, various test runs are carried out for the validation of the simulated assumptions.

The required system parameters are monitored. The greywater-filtrate is qualitatively examined to determine its basic compatibility as an irrigation agent. Based on a plant trial, the actual tolerability is examined over a longer period of time, whereby a parallel experiment of a plant control group, which is irrigated with drinking water, takes place.

A selection of plants that are interesting for the climatically active greening and also greywater-filtrate compatible is to be defined. The investigations also evaluate the available greywater supply in residential buildings, considering different types of users. The recovery potential including possible application limits of greywater-filtrate will be known.

Project Partners

Project management

Schöberl & Pöll GmbH (consortium leader)

Project or cooperation partners

  • GEBE-STREBEL GmbH (applicant)
  • OeAD-Wohraumverwaltungs GmbH
  • Institute of Building Research & Innovation ZT GmbH
  • Universität für Bodenkultur Wien – Institut für Ingenieurbiologie und Landschaftsbau (IBLB)

Contact Address

DI Klemens Schlögl
Schöberl & Pöll GmbH
Lassallestraße 2/6-8
A-1020 Wien
Tel.: +43 (1) 726 45 66/14
Fax: +43 (1) 726 45 66/18