Environmental Engineering Reference
therm al heat boiler
drinking water boiler
thermal heat solar
drinking water solar
Figure 6.20 Typical progression of thermal heat and hot water requirements in Germany
and proportion of solar system versus conventional heating based on the requirements
of an old building with a total solar coverage of 20%.
■ Collector surface with vacuum - tube collectors: 0.6 m 2 per 10 m 2 living area
■ Storage size: at least 50 litres per m 2 of collector surface
Variant 2: Medium-sized system for higher share of solar coverage
■ Collector surface with fl at - plate collectors: 1.6 m 2 per 10 m 2 living area
■ Collector surface with vacuum - tube collectors: 1.2 m 2 per 10 m 2 living area
■ Storage size: 100 litres per m 2 of collector surface
An optimal design would of course also take into account the actual heat require-
ments. The difference in requirements between an old building and an energy-saving
three-litre house is considerable. Table 6.1 shows simulation results for optimal
systems that were dimensioned according to the outline design described.
Table 6.1 Solar coverage.
Heat requirement for hot water in kWh
Heating requirement in kWh
Solar coverage Variant 1 (small system)
Solar coverage Variant 2
Assumes following: Berlin location, orientation 30 ° south without shade, 130 m 2 living area, optimal fl at-plate collector with combination storage.
Although the collector with the medium-sized system is double the size of the small
system and the storage is four times larger, this does not mean that the solar cover-