16C? I wouldn’t have thought that was even possible when ambient temperatures are above 30.

When I was still working the management of the company maintained that they were prevented (by law or regulation?) from reducing the ambient temperature by more than 5C. This was Geneva city and canton and I don’t know if it was true.

I would first ask at your local commune if regulations apply.

I would also look at other options (geothermal cooling; window protection; etc.)as well.