EES Engineers Put a Wooden Stake into the Heart of Vampiric Outdoor Lighting Time Clocks

Posted by Daniel F Luna, P. E. on Apr 24, 2023 8:30:00 AM

EES lighting systemsLighting based on time clocks can sometimes feel like it’s a draining the life out of your wallet. EES tackles this problem with a simple, closed-loop control solution.

Vampires and outdoor lighting have something in common: they are supposed to be active at night and dormant during the day.  Mythology and movies are replete with vampires missing their window to get back to the safety of the shadows, but little is said about parking lot lights controlled by evil time clocks.

Ray-Ban sunglasses and sunscreen may save a vampire, but they won’t help a poor building manager who has to deal with simple time clocks for control of the parking-lot lights.

For a good many years, simple time clocks have been used to turn on and off parking lot and building night lights.  Some became more sophisticated, providing astronomical clock mechanical calculations for the turn on times. This was to follow the changing amount of daylight, but little for the when the time is off.

Many buildings have a simple 24-hour clock that turns the lights on and off.  This is not an ideal situation for building managers because the clock needs to be adjusted several times a year, by hand.  

These clocks cause a multitude of problems: my team hears the complaints all too often. Both night and day suffer. At night, those who are in the building need more light. They face a serious safety issue if the building is too dark. Then during the day, the people who pay the electric bill are frustrated when their lights stay on during daylight. They’re just throwing money out the window.
When you call EES to help out, we do a multitude of things.  One task we take on is to put the outdoor lighting on a photocell. That way, the lights exactly match the length of the night at all times.  This also addresses lighting issues when there are bad-weather days and during the time of year when it gets dark early.

Open and Closed Loop Control

This is a good opportunity to dive into the topic of open- and closed-loop control, which I do when training folks on control.  Open-loop control does not measure the variable it is trying to control.  Like the timeclock controlling lumens, it does not look at the amount of daylight to decide when to add more light.

Imagine if your home’s heating was open loop.   The open-loop controls would struggle to maintain a certain temperature in your home. This is because an additional system would have to account for the weather, your home’s nascent energy loss, how much cooking you did, and so on.  It would have no idea that when you burnt the roast and opened the windows you also let the heat out.  It also doesn’t account for how much heat your TV and other electronics generate.

Closed-loop control measures the variable it is controlling. Keeping with the example of heating your home, close-loop control would simply measure the temperature.  When the temperature is measured  below a desired number, the controls turn the heat on.  When it reaches the desired number, it turns the heat off.  No elaborate calculation about thermal transfer and such.  Cruise control in your car is another example of closed-loop control.  Imagine how hard it would be to figure out how much acceleration you would need, minute by minute, without it.

Lighting in an Open and Closed Loop Control

Going back to lighting, most buildings and parking structures that have not been updated operate on an open-loop control system. Meaning the lights are not accounting for any other variable other than time; the lights are not measuring light.

Lights that utilize closed-loop control monitor the light levels outside and add more when needed, not based on a schedule like with open-loop control.  This maximizes the energy saved.  Neither safety nor cost are compromised: all stakeholders are given the best possible outcome.  Money is saved and risk is averted.

Consider EES your Van Hellsing to this vampiric lighting problem. Reach out to us today to update your lighting system and start saving money.

Topics: controls, control systems, engineering, dan luna, open-loop controls, outdoor lighting system