Concentration, performance, communication, mood, satisfaction, health: everything suffers.
The result: although management believed that open offices increase the productivity and satisfaction of the workforce, the opposite is actually the case.
They felt disturbed more often by other people's conversations at work and complained more often about stress and physical complaints such as tiredness or headaches.
The consequences for health were also documented in a survey of more than 2,400 office workers in Denmark.
They counted 62 percent more sick days in open-plan offices with seven or more people compared to individual offices.
Having to listen in on other people's conversations is the biggest disruptive factor when concentrating on work.
No partitions, table dividers or sound absorption on the ceiling can help: a room-high partition is needed.
In surveys, only up to 30 percent of employees complained about distracting conversations from others if they had such opportunities to retreat - without this, the figure was up to 70 percent.
For open-plan offices, this means on the one hand: allowing free choice of space, for example via booking systems.
The main thing is to show consideration, for example by speaking quietly or moving telephone calls to designated areas.
Not involving employees at lower hierarchical levels - or only involving them in order to convince them of something that has already been decided.
Open-plan offices inhibit communication.
When employees moved from small offices to open-plan offices, the number of face-to-face meetings fell by around 70 percent - instead, they sent up to 50 percent more emails and other electronic messages.