Environmental Engineering Reference
In-Depth Information
If no leakage is assumed for normal operation - which should be easy to realise
applying modern system technology - no such environmental effects will occur.
Thermal effects on the soil, the groundwater and the atmosphere.
The utilisation
of heat in the ground, the groundwater or the near-surface atmospheric layers by
heat pumps leads to a corresponding cooling effect.
In vertical ground probe systems, for instance, temperature decreases of up 2 K
occur within a distance of 2 m. If systems are dimensioned correctly, a thermal
balance is established in the long-term. Additionally, the influence of the heat
withdrawal remains at a local level. Furthermore, a moderate cooling of the
ground has no known effect on its structure. Icing caused by an excessive heat
withdrawal and the ensuing thawing process can change the structure in fine-
grained soils (e.g. clay), which can cause the soil to sink around the built-in verti-
cal ground probes /9-21/. As there are normally no living creatures or plant parts
at the normally used depths, the cooling does not lead to any known ecological
impairment. Additionally, the influence towards the surface of the earth is negli-
gible and is offset by the solar radiation heat. A negative impact on the groundwa-
ter can be excluded as well.
If vertical ground probes are used, they have a certain influence on the ground
fauna and vegetation. The range of influencing factors depends largely on the sys-
tem design. If the collectors are too small in dimension, the activity level of the
ground fauna (e.g. earthworms) is reduced - due to an excessive cooling of the
ground - to a large extent. It also leads to e.g. a considerable delay in vegetation
and a reduction in harvest amounts and flowers. If systems are designed appropri-
ately, which should always be aimed for, these effects are comparatively small.
For example no systematic change could be discovered in certain beetle popula-
tions which could have been caused by heat withdrawal by heat pumps with
ground-coupled collectors /9-21/. During the summer, the same temperature level
is achieved as without using collectors. A significant impact on the groundwater
can also be excluded - due to fairly shallow excavations to lay the probes.
The situation is similar in the case of heat withdrawal from the atmosphere.
The heat exchange - compared to heat withdrawal from the ground or the
groundwater - between individual fractions of air in near-surface atmospheric
layers is significantly more intensive. Thus a possible impact of cooling can be
balanced immediately. Related environmental effects have therefore not been ob-
served so far. Furthermore, the heat withdrawn from the ambient air for heating
purposes is discharged to the ambient air again by the building.
Additionally, due to cultural influences, the temperature of the ground, the
groundwater or the near-surface atmospheric layers has increased in many places.
Therefore cooling down can be positive. Up to now, no significant negative as-
pects of the cooling of ground, groundwater or near-surface atmospheric layers by
heat pump systems have become known.
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