This is a great paper written up by UC Davis showing the benefits of lighting controls in classrooms. Laney College used rebates and incentives to offset costs and save $17,500 annually. Laney College also has a great electrical trade program. Add the two together and you have a recipe for success.case_study_icls_laney_college_aug2013

Does anyone even really know what “411” is anymore or have I dated myself? I digress…

In offices buildings, lighting can account for 15%- 20% of energy use. Lighting controls, when properly used, can reduce that by 25%. Because there are diverse types of controls technologies and applications, it is recommended to game plan accordingly.

First used in the 70’s as an alternative to microwave and ultrasonic motion detectors, Passive Infrared (PIR) detectors promised lower costs and false alarms. The technology originated at Optical Coating Labs in California. PIR motion detectors use thermal sensors which detect small temperature increases.  Ultrasonic motion detectors detect occupancy by sending out ultrasonic sound waves into a space and measure the speed at which they return. As movement by a person occurs, frequency changes and triggers the sensor.

When sensors are used correctly they can be highly efficient at saving energy, keeping occupants safe and keeping lighting fixture maintenance costs low. When used incorrectly, sensors can be a burden on occupants and cause more headaches than they cure.

New and improved sensor technology make it so occupants never give the sensors a second thought. With dual technology sensors, unless an occupant is napping under his/her desk, there is no worry of lights being turned off while an occupant is in the room. With switched plugs clearly marked, occupants don’t have to worry about PC’s being shutdown improperly and unexpectedly.

Let’s talk a little more about the basic technology behind occupancy sensors:

Passive Infrared Motion Detection

PIR (Passive Infrared) occupancy sensors are best used for detecting large or major motion like an occupant walking through a space.  PIR works by detecting movement of heat sources in the space. It can only detect heat in its direct range of view and its cover is directional and limited to line of sight. Thus, planning and design are key with this type of technology. Since PIR only detects large movement, they are prone to false offs. Here is an example of a Wattstopper PIR ceiling sensor CI-355:

Ultrasonic Motion Detection

Ultrasonic technology in occupancy sensors is used for minor or small motion detection. This makes ultrasonic an appropriate choice where small movements, such as working at a desk, takes place for extended periods of time. As previously mentioned, ultrasonic works by emitting an ultrasonic sound wave into the space and measuring the frequency. When there is movement in the space, the signal bounce back is read differently and the sensor knows there is movement in the space. Ultrasonic technology can detect motion even around corners. Limits to this technology include: higher power needs and false triggers. Here is an example of a Lutron ultrasonic ceiling sensor LOS-CUS-1000-WH:

Dual-Tech Motion Detection

Like it sounds, dual-technology combines both ultrasonic and PIR sensor technologies to provide optimal detection, with minimal false reads. The occupancy sensor will not turn on the lighting until both PIR and Ultrasonic elements are triggered. Once a light is turned on, the sensor only needs one of the technologies to keep the lights on. This helps ensure the lighting is not turned off while the occupant is in the space. Dual-technology sensors are more expensive (though not much), but are more effective. Here is an example of a dual technology ceiling sensor from Wattstopper DT-355:

Here is an example of a dual technology wall mount sensor by Wattstopper DSW-100:

Occupancy with Daylight Sensor

Some occupancy sensors are equipped with a daylight sensor that allows the installer to set a light level at which the occupancy sensor will not trigger the lighting on based on daylight in the space.  So, the end user can save additional money by not using lighting if the space does not require it based on natural light.  Generally, you can adjust sensitivity according to your interest.  These are only used to detect the lighting in the space to switch lighting on or off, depending on the light levels and they are not applicable to certain energy codes that require daylighting and dimming requirements.

Occupancy vs. Vacancy Sensors

Occupancy sensors generally are equipped with Auto –On setting so when an occupant enters the room, the lights turn on.  Some have the ability to switch to a Manual- On, a vacancy setting, meaning that the lights will turn on only if the occupant turns the light on at the switch.  However, it will detect movement and keep the lights on until the occupant leaves the room, at which point the sensor will detect vacancy and turn the lights off.

Have questions about which sensor is right for your job? Contact us at literitecontrols.com and we can help. Already have sensors in mind? Check out literitecontrols.com for the best pricing.

Different Types of Light Dimming

In the old days, light dimming is through a variable resistor. As the nob is turning, the amount of resistant will vary which makes the current delivered to the load vary. Therefore, the voltage drop caused by the resistive nob will decrease the load voltage and dim the light down. The disadvantage of this is its inefficiency, it doesn’t save any energy since the applied voltage and current are the same between the dimming load and non-dimming load. Current must travel through a resistive nob so the energy is wasted as heat from the resistive nob. It can also be potentially dangerous since it creates a lot of heat.

Incandescent Dimming (Also referred to as 2-Wire Forward Phase Dimming)

The use of incandescent dimming can reduce energy consumption and increase lamp life. Since incandescent lights uses resistive filaments, it can be dimmed by most electronic dimmers. Typical incandescent dimmers such as Lutron DV-600P. These dimmers use a silicon device, usually an SCR or a Triac, to turn the AC waveform on part way through its cycle. By varying the point at which the waveform turns on, we can alter the amount of power delivered to the lamp. Incandescent dimmers cannot be used to dim low voltage loads, but magnetic low voltage dimmer or electric low voltage dimmer can be used to dim incandescent loads.

Benefits of Incandescent Dimming:

• Incandescent compatible LED Drivers/lamps work with most 2-wire forward phase dimmers making them perfect for many retrofit applications.
• Some LED Drivers are specially designed to eliminate the problems associated with using 2-wire forward phase dimmers with LED fixtures including flicker, ghosting, pop on, drop out, etc.
• 2-wire forward phase dimmers are the least expensive and have the most installations in the marketplace. In many cases, these dimmers are less expensive than electronic low voltage dimmers or 0–10V dimmers.
• Generally, provide smooth dimming down to 10% depending upon the dimmer’s limitations.

Drawbacks of Incandescent Dimming:

• 2-wire forward phase dimmers should not be used with ELV drivers because doing so could cause any of the following malfunctions: dimmer buzz, lamp flicker, interaction between circuits or radio frequency interference (RFI).
• At times, noticeable noise in a forward phase dimming system can be observed as the filaments of the lamps are being dimmed. When the power is turned on to the lamp part way through the waveform cycle, the filament expands very rapidly, and then as the voltage ramps back down again the filament cools. This rapid cycle of expansion and contraction leads to “Lamp Sing” (an audible hum that can be objectionable).

Magnetic Low Voltage Dimming

Modern dimmers chop up the sine wave and turn off the circuit whenever the voltage switches polarity and turn it back on. The amount of time it turns off will dictate how bright the light will be. If the dimmer is set on a lower light, then the turn off time will be longer. If it’s on a brighter setting, then the turn off time will be shorter. It usually has a very smooth turn off period.

Magnetic transformers step down the 120 VAC line voltage into 12 VAC or 24 VAC. It uses copper winding around a steel core to produce magnetic flux. It’s usually rated as Volt-Amp because it’s heavily inductive and produces reactive power; which we need to take it into account for on the rating. Dimmers with magnetic low voltage transformers use the technology known as “leading edge”, it’s often used with inductive loads such as motors.

Drawbacks of MLV Dimming:

• Typical incandescent dimmers cannot be used to dim low-voltage lighting systems, nor they can be used to dim fluorescent lights. DO NOT USE REGULAR INCANDESCENT DIMMER ON LOW VOLTAGE DIMMING. It produces a small amount of DC voltage which may harm the magnetic transformer.

Electric Low Voltage Dimming (Also referred to as Reverse Phase Dimming)

Electric transformers step down the 120 VAC voltage to 12 VAC or 24 VAC using electronic circuitry. It’s usually very small compare to magnetic transformers. They tend to have capacitive input which leads the current, and will require a trailing edge waveform for dimming. It’s very smooth to turn on but requires a Neutral wire connection.

Benefits of ELV Dimming:

• ELV dimming drivers are generally widely tested and approved by dimmer manufacturers for LED loads.
• Generally, 2-wire reverse phase dimmers work better on LED Drivers than most 2-wire forward phase dimmers. The reason is that most LED Drivers use Electronic Low Voltage (ELV) Transformers. These transformers are generally capacitive type loads which work much better when controlled by Reverse Phase dimmers.
• Allows smooth dimming down to 5% depending upon the dimmer’s limitations.

Drawbacks of ELV Dimming:

• 2-wire reverse phase dimmers can be more expensive than forward phase incandescent or magnetic low voltage style dimmers.
• Smaller install base could mean replacing incompatible dimmers on retrofit projects.
• 2-wire reverse phase drivers should not be used with forward phase dimmers because doing so could cause any of the following malfunctions: dimmer buzz, lamp flicker, interaction between circuits or radio frequency interference (RFI).
• 2-wire reverse phase dimmers require a neutral wire. This can result in having to pull additional wire on remodel projects.
• Some architectural loads (e.g., linear fluorescent) perform better when dimmed with ELV dimmers. However, it is very important to refer to the luminaire manufacturer’s datasheet to verify compatibility of forward or reverse phase dimming.

0-10 V Dimming Also Referred to as 4-Wire Dimming)

Low voltage 0-10 V dimming are usually used on LED or fluorescent lights. It uses low voltage 0-10 VDC signal connected to each LED power supply or fluorescent ballast. 0 V would be the minimum brightness and 10 V would be the maximum brightness. Its most common applications would be LED lighting fixture with 0-10 V dimming input. It usually requires a power pack providing DC power to the 0-10 V dimmer.

Benefits of 0-10V Dimming:

• Use existing 0–10V systems in retrofit applications.
• Large 0–10V install base in commercial applications due to IEC standards.
• Allows smooth dimming down to 5% depending upon the dimmer’s limitations.
• Compatible with many daylight harvesting controls, occupancy sensors, and building automation.

Drawbacks of 0-10 V Dimming:

• Some manufacturers do not follow the IES standard. This leads to LED Drivers and lamps that claim 0–10V compatibility but drop out or pop on, or dim backwards with the lowest output at the top and the highest output at the bottom. Also, a function of correct pairing of LED Driver and LED load.
• The control signal is a small analog voltage and long wire runs can cause a signal level drop that can produce different light levels from different drivers on the same control circuit.

Digital Dimming (Also Known as Dali)

With digital dimming, the driver receives a digital signal which tells it how to respond. The advantage of digital dimming is that fixtures are addressable. You can also have many more different levels of light output when using digital dimming. Light fixtures require a Dali Driver and were more common among fluorescent fixtures.

Reference:

http://home.howstuffworks.com/dimmer-switch.htm

http://ecmweb.com/lighting-control/shining-light-dimming

http://reader.mediawiremobile.com/Lutron/issues/107167/viewer?page=91

http://www.lutron.com/europe/ResourceLibrary/362219.pdf

https://www.acuitybrands.com/products/detail/257121/fresco/fresco-dxt/assemblies-for-high-performance-dmx-networks/-/media/products/fresco/257121/document/0-10vdc-best-practice_pdf.pdf

http://www.lutron.com/en-US/Education-Training/Pages/LCE/DimmingBasics.aspx