Upgrades building insulation and air tightness, to allow
heat delivery to be effective. Wet soils and areas with good
movement are best.
For horizontal collectors, adequate land area is needed - a rule thumb is at least
  for each Kw of capacity.
Under floor heating can rarely be retrofitted, so replacement of
or fan coils may be used instead.
Space for the heat pump unit and an
buffer tank.
For boreholes a
survey is recommended.