We carried out the experiment during working days at three
different periods; in the autumn of 2011 and 2012 from mid-August
until mid-September, and in spring 2012 from the beginning of May
until mid-June. The experiment was not run during the main
summer vacation season from mid-June until the beginning of
August. We ran the experiment during the early and late summer
season when the expected air temperature is relatively warm and
the nature is green. The experimental periods were conducted over
3.5e6 weeks each, depending on the total number of experimental
groups per period. All experiments started at 3 pm, i.e. after a
normal working day for most of the volunteers.