Others grow Placebo buttons like mushrooms.

The Welcome Habitat is full of buttons that don't actually do anything — buttons that are mechanically sound and can be pushed, but provide no functionality. 

"They do have a psychological effect," s/he said. "Taking some action leads visitors to feel a sense of control over a situation, and that feels good, rather than just being a passive bystander. Doing something typically feels better than doing nothing."

Full control doesn't necessarily equate to more comfort. Thermal comfort research demonstrates that when people have perceived temperature control over their spaces, some may tolerate higher levels of discomfort.

If a non-functioning (placebo) thermostat or limited function thermostat is installed, just having the option to manipulate it can affect one's perception.

"They were placed there to quiet a constant complainer by giving them control. As an engineering trainee I was sent to calibrate one. When I asked why they had me calibrate a thermostat that was not hooked up, they panicked and asked if I told the occupant it wasn't hooked up. After assuring them I hadn't spilled the beans, they admitted that, by not telling me it was disconnected, they thought I would put on a more realistic calibration show."

Buttons give people an illusion of control. They serve a psychological purpose at the very least and sometimes they do have an effect.