Page 118 - ISES SWC50

Martin Zogg
Country: Switzerland
Year Started Research: 1975
Title of Research: Computer simulation of solar water heating
University: University of Applied Sciences, Burgdorf
Still Active in Research: No

The widely diverging predictions for the usefulness of solar water heating motivated Martin Zogg, professor
in process engineering at the University of Applied Sciences in Burgdorf (Bern), to the first dynamic
simulation of a complete thermal solar system in Europe. In 1975/1977 Zogg developed a pioneering
program based on hourly meteorological data. Because there were no experimental data available even
the collector efficiency had to be calculated. As confirmed by later validations, the pioneering program
was already able to reproduce the dynamic behaviour of a solar hot water heating system quite precisely.
This made it possible for the first time to determine the profitability of solar hot water systems and to design such
systems in a well-founded way. In 1977 Zogg published his calculation models in detail. That aroused the interest
of Gerhard Schriber, the later head of the Swiss Energy Research Program. He enabled the further development
by several projects at the University of Applied Sciences in Burgdorf. Under the direction of Zogg and Roland
Hungerbühler, Medard Rieder and Markus Arnet as scientific assistants the following upgrades were made:
1981 Integration of experimentally determined collector efficiencies;
1982-1983 Thermally stratified storage tank, analytical solutions, improved solar radiation conversion;
1984 Systems with two stratified storage tanks and further control concepts;
1985 Validation on experimental reference systems;
1986-1987 Dimensionless number method for assessments without simulation, simulation of thermosiphon
systems;
1988 Integration of systems with combined water and space heating.
However, the ten-year path to a general recognition as a planning tool was quite painful. The turning point came with
the validation of the simulation programs on reference systems. The practitioners were amazed that the calculated
results matched the measured results within the scope of the measurement accuracy. Today, Zogg’s ideas live on in
the much more advanced and extended program “Polysun”.

100 | ISES SWC50 - The Century of Solar-Stories and Visions