Twilight Photos vs. Occupancy Sensors

[David E. Rose]

I have a question for the architectural photographers in our forum. I am shooting a recently completed project that has a sustainable focus and therefore uses occupancy sensors for the lighting in most rooms. A twilight shot is desirable, but the building is never fully occupied, so the lights go off in the un-occupied spaces, leaving parts of the facade dark. The lighting designer confirms that there is no override switch for the lights. The sensors are the latest technology (PIR) and require movement to trigger them. Have you run into this and does anyone have a solution for activating the lighting short of having a person stationed in each room?

[Kirk Gittings]

Small world.......see the latest entry in my blog.

[spiky247]

how long do you plan on exposing? maybe have an assistant "drive" remote controlled car through the corridor?

[Vaughn]

Rig up a little pendeleum (sp?) in front of each sensor (a machine nut on a string suspended out form the sensor if wall mounted)?

[Marko]

Tie a balloon - the kind you can buy in most supermarkets - to a small fan in front of every sensor you want to keep active.

[argos33]

I like the gerbils idea - just release a couple hundred in the building and you shouldn't have to worry about them going off!

Really I think it depends on how long they stay on once motion has stopped. Vaughn's idea sounds like a good one to me.

[David E. Rose]

Guys,
Thanks for the suggestions, humorous and otherwise. Kirk, thanks for the link to your blog. I was not aware that you were doing that and your efforts to share knowledge are very much appreciated!

The intent for this twilight shot is a series of exposures of one view over the course of a half hour or so. The individual exposures will be bracketed, and probably not run any longer than a couple of seconds. The idea of placing some moving object in each room was my initial thought. I keep looking at my son's toys for likely candidates. One of the problems is that the sensors have become more difficult to fool as they have become more sophisticated. The other issue is that the latest designs have the ability to learn the use patterns of the room and adjust the turn-off time to achieve the best energy efficiency and convienence for the normal occupancy. This means that the shut-off time after no movement varies.

As sustainability and energy efficiency become normal design criteria, I believe that we will face this challenge frequently. We need to find the perfect cheap wind-up or battery driven moving object (toy) that will keep the lights on!

[Kirk Gittings]

I like the fan idea, perhaps a small cheap oscillating type, but I think I will test it with a piece of crepe paper or ribbon attached rather than hassling with balloons. Something like this:

http://www.jr.com/holmes/pe/HMS_HACP9/

[Paul Metcalf]

So what do the owners do when they want to sit quietly and read a book? Wave their arms every few minutes? I can't imagine why there isn't an override, and if I were king (for the day) I'd make it part of the electrical code to have a manual override. (And how long will it take for criminals to figure out that a "sustainable" house is unoccupied when the lights are out. Sheez) But of course I'm never king.

Does the house have central air or heat? You could turn the fan on the air/furnace (assuming it has a manual switch unlike the lights) and have crepe paper attached to each outlet in each room.

[Arne Croell]

Guys, with respect to the ideas with fans, ballons, etc.: Not all, but most motion detectors are based on the change of IR radiation in their field of view, such as when a human body with a higher temperature than the surroundings passes by (see: http://en.wikipedia.org/wiki/Passive_infrared_sensor). If the moving fake object has the same temperature as its surroundings, nothing will happen. Otherwise, any movement of, say, a curtain due to airflow would trigger it.