Heat Harvest - Harvest of urban solar excess heat from buildings and surfaces to avoid summer overheating in cities

"Harvest" of solar urban excess heat from building surfaces, sidewalks, streets and squares to avoid urban heat islands by lying flat absorber pipes, which are then fed into geothermal probe storage tanks for later use as a source for heating buildings.

Short Description



Starting point / motivation

To avoid urban heat islands, greening measures as well as green and/or water surfaces are already being propagated and used in many places. However, the use of these solutions is not always sufficient, approvable or desirable, such as in old, historic or listed buildings.

Contents and goals

A simple, invisible and seasonal solution is the "harvesting" of solar urban excess heat from building surfaces, sidewalks, roads and squares through shallow absorber ducts, which are then used in borehole heat exchanger (BHE) fields for later use as heat source for the buildings.

However, since temperatures in urban surfaces are sometimes very high (up to 50 ° C) and these cannot easily be introduced into BHE fields, common calculations and simulations are not sufficient to accurately predict the thermal behaviour of the subsoil in the densely built sensitive urban space with a lot of area competition.


Conventional calculation and simulation methods for the design of BHE fields are limited by the conditions that occur in strongly heated inner city areas, or simulations with higher temperatures are not easily possible.

The underground temperatures of a city are already increased by building and use compared to the climatic conditions. The introduction of waste heat for seasonal storage and the integration of heat pumps is therefore very sensitive and must be based on reliable and accurate figures and calculations.

Expected results

The aim of the project Heat Harvest is to carry out comprehensive investigations of the thermal behavior of the subsurface in the case of solar thermal waste heat in a large-scale test facility on an open-air site and accompanying laboratory experiments as well as simulations under different conditions.

In this way, the appropriate framework conditions for the harvest of solar waste heat in urban areas can be explored purposefully to later embed the approach into a larger cooperative research project.

Project Partners

Project management

AIT Austrian Institute of Technology GmbH

Project or cooperation partners

  • TERRA Umwelttechnik GmbH
  • Geologische Bundesanstalt

Contact Address

DI Dr. Edith Haslinger
Giefinggasse 2
A-1210 Wien
Tel.: +43 (505) 50-3608
Fax: +43 (505) 50-6390
E-mail: edith.haslinger@ait.ac.at
Web: www.ait.ac.at