Successful properties have lighting that suits the needs of their occupants. Proper lighting can boost productivity, mood and an overall sense of worker wellbeing. While bad lighting can do the opposite. Light flicker is detrimental to the workplace, often causing migraine headaches, eye strain and general eye discomfort in workers. Even worse, light flicker can often be a hidden danger, going unnoticed for months or years while negatively affecting occupants. Understanding and detecting light flicker ensures a healthy and safe working environment.
What is Light Flicker?
Light flicker is the repetitive and rapid changing of a light brightness over time. Such light repetitions are too fast for most humans to see but can still produce negative side effects in individuals with sensitivities, including headaches, nausea and eye strain.
Lights flicker because of their power source. Most facility light sources run on alternating current (AC) electricity. AC produces electrical cycles that fluctuate from positive to negative. Power starts at zero, grows to a maximum positive charge, then reverses itself to a maximum negative charge. These cycles are measured in hertz, and most power is delivered in 50 or 60 hertz.
Because most industrial and commercial lighting runs on AC current, their bulbs must also follow a similar alternating cycle. Illustration 1 shows the alternating waveform of a standard incandescent bulb. The bulb cycles through a maximum positive charge to a maximum negative charge. Essentially, the AC power supply is turning the incandescent bulb on and off.
However, as the bulb’s cycle moves from one maximum charge to another, it passes through a lower voltage. Therefore, the bulb goes from bright to dim to bright again. It’s these repetitions that cause light flicker.
Illustration 1. The typical alternating voltage waveform for an incandescent bulb. These changes in voltage are why light flicker happens.
We normally don’t notice light flicker because of the speed at which it occurs. Lights reach maximum brightness twice in each cycle, so at 60 hertz power, that’s 120 cycles or 120 times per second! At that speed, the light appears to be “on” all the time. This is why turning (slowing) down an incandescent bulb using a dimmer switch can produce a visible flicker.
Ways to Detect Light Flicker
To eliminate light flicker, first you must locate it. The easiest place to start is your “Suggestion Box” or tenant satisfaction survey. Are you getting complaints about the lighting? You may have a big problem, even if it’s only a small group of respondents. Remember: not everyone is susceptible to light flicker effects, so don’t let “only a few complaints” lull you into a false sense of security.
If you do suspect there’s a problem, go through and test suspected areas of your building. The easiest way to detect light flicker is to take a photo of a fast-moving object. Snap a photo with your smartphone of an object like a ruler (see Photo 1 below). If you can see discrete positions of the ruler (left), the lighting has a high light flicker. But, if the position blurs together (right), it has a low light flicker.
Photo 1: The stepped appearance of the waving ruler on the left photo indicates high flicker rate in a bulb, while the blurred left image indicates a bulb with less flicker. Photo courtesy of Susan Mander.
Another strategy for testing for light flicker is to use your smartphone’s camera app. Most people have at one time or another witnessed dark horizontal bars appear on their phone’s screen when they view light sources such as LED bulbs, computer monitors or TVs. These horizontal bars form because the camera’s video frame rate and/or screen refresh rate is high enough to capture the source’s dimming light cycles.
To test a bulb for flicker using your phone, take a photo of the light source, a “slow mo” video or simply hold the phone close to the source while viewing a live image. If there are horizontal bands of dark bars, there is light flicker (Photo 2).
Photo 2: Slow motion video reveals dark horizontal bars across a light source like an LED bulb or computer monitor. Photo courtesy of Susan Mander.
Reducing the Effects of Light Flicker
You can combat light flicker with natural light. Since light flicker exists because of the fluctuation from bright to dim, you can use natural lighting, which has zero flicker, to fill in the gaps. While sunlight isn’t a substitute for quality bulbs and proper electrical system upkeep, it can be a good short-term solution. What’s more, natural lighting has other benefits to the physical and mental health of workers.
Fluorescent Bulbs
Early in their development, gas-filled linear fluorescent bulbs were notorious for producing light flicker in office buildings. Early models caused worker headaches and eye strain, but the later switch from magnetic to electronic ballasts eliminated the flicker along with the complaints.
Today, linear fluorescents and their small cousins the compact fluorescent bulb (CFL) enjoy widespread use. However, fluorescent lights can still produce light flicker for a variety of reasons.
Like any bulb, these gas-filled illuminators work less effectively with age. And, unlike incandescents, they don’t suffer catastrophic failure. That is, fluorescents won’t simply go out. Instead, they will continue to work even if only way. That means flickering side effects could go on for some time. So keep fluorescent bulbs fresh. If replacements are still flickering, you may have a bad ballast, especially if you hear a hum.
LED Bulbs
LED bulbs are the growing trend in facility illumination because they’re more efficient than incandescents and fluorescents. LEDs also extend bulb life, with a run time of around 20K to 100K hours.
Instead of tungsten filaments and gas vapor, LEDs use electronics (light emitting diodes) to produce light. Because of this, they tend to have a harsher AC flicker wave profile than other bulb types. So, bulb designers attach electrical components in the LED bulb’s base to reduce flicker.
However, when it comes to light flicker and LEDs, it’s a buyer beware situation. You usually get what you pay for. Some LEDs have almost no flicker, while others have an abundance. It all depends on the quality of their electronics. Perform your own flicker detection tests before you decide.
Mander, Susan. “Key Lighting Principles for Facilities Managers.” Presented 15 June 2021. Online presentation for Facilities Managers Association of New Zealand.
Are you finding it hard to procure office equipment? Is your supply closet running short on toilet paper? Supply chain issues are a global problem, and shortages are hitting every sector. Office managers in the U.S. are finding it hard to locate basic office supplies like paper, printer ink, lightbulbs and, yes, even toilet paper.
Trade experts say the global supply chain conundrum could be years away from resolving itself. So, many firms will need to adjust their procurement practices to locate alternative resources and manage rising costs. To that end, here are five tips for surviving the supply chain issues you’ll want to try out this year.
1. Barter with Competitors
Supply issues are prime times for beefing up your business relationships or calling in old favors. If you have excess resources, find a competing property owner who needs them and offer a trade. Such transactions could also include services-for-supplies too. Don’t be too proud. Cooperation helps the whole industry win. NOTE: Depending on where you do business, you may be required to report such bartering “profits” as taxable income. Check with your CPA.
2. Buy Used, Source Local
With international supply chains still struggling, many are looking to local and/or second-hand stores for procuring used supplies like office equipment or furniture. Look at both brick-and-mortar and online stores. On trading platforms like Craigslist, eBay or TradeMe you can easily filter searches by location to find products/services within a workable range for quick delivery. Buying used cuts down delivery time and gets the job done until you can find replacements. It’s also better for the environment!
3. Reduce Your Use
One upside to doing without is learning to live with less. Supply shortages are great opportunities to launch campaigns around efficiency and cost cutting. Use less paper products by transitioning to digital documents. Is your disposable coffee cup supply running low in the break room? Then buy your staff personlised mugs. Necessity is the mother of Invention, so use an unpredictable situation to promote conservation and frugality among your team and tenants.
4. Promote Flexible or Remote Working
By embracing the remote work trend, you can offset some supply use and costs to workers, many of whom will be happy to trade sweatpants and a much shorter commute. Besides using fewer resources, flexible work models offer more benefits for both employees and companies including increased productivity and higher retention.
5. Prepare for Tenant Backlash
Lack of supplies inevitably trickles down to your tenants. Sidestep complaints and backlash by preparing them before scarcity hits. Here are a few themes to weave into your tenant messaging.
Fairness. Some tenants may feel others are getting preferential treatment. Strong messaging is needed here. Any emails or correspondence needs to firmly dispense with such rumors before they grow. Maintain a voice of empathy and understanding around the shortages and their implications.
Transparency. Keep tenants abreast of delivery updates. Being in the dark is worse. When tenants can see there’s an end in sight, their patience increases dramatically. But even if you have no idea, be honest about your situation; sincerity does the heavy lifting when it comes to acceptance of a bad situation.
Collective Struggle. Take a “We’re in this together” approach. Groups get through things easier when there’s a feeling that everyone is sacrificing. However, this isn’t a time to point out how you’re the victim too; don’t unwittingly create a competition for “who’s got it worse.” Instead, stress collective sacrifice as a balm for individual angst and impatience.
Fire protection systems are one of the most complex and ubiquitous structures within facilities today. They contain many parts intertwined with other building components. For example, emergency lighting and smoke detectors wire into your electrical system. Fire pumps and hydrants hook up to your water mains. Fire alarms connect to your building’s access system to automatically unlock exterior doors.
Your HVAC system is also closely coupled to your fire protection equipment, and its maintenance and condition can directly impact the safety of your inhabitants and the extent of damage to your property.
1. Ductwork
Your system’s ductwork distributes conditioned air throughout the building. But during a fire, such distribution is unwanted. As temps rise and smoke builds, your HVAC’s return ductwork can carry smoke, toxic gases, and superheated air throughout other areas. This spreads the fire and puts occupants in danger. Even worse, supply side ductwork can actually “feed” a localised fire with fresh oxygen, increasing the temperature and property damage.
During a fire, smoke is the number one killer. In fact, most fire deaths are not caused by burns, but by smoke inhalation. Therefore, controlling its spread is safety 101. Plus, smoke can often emit from sources besides an open flame. Burnt toast or microwave popcorn could result in smoke rolling through an entire office floor. This could cause a panic and dangerous stampede to exits. So, any fire safety plan should also include the perception of fire itself as a real threat to life and property.
Duct smoke detectors can help. These devices reside within your ductwork where they detect smoke moving throughout your HVAC system and initiate pre-programmed actions. For example, one of your HVAC fan motors overheats and produces smoke. Once activated, the duct detector could turn on an exhaust fan, close a damper, shut down automation systems, signal an alarm and/or cut power to the fan motor itself.
2. Fire and Smoke Dampers
Fire dampers are another critical way your HVAC systems aid your facility’s fire protection system. Dampers are essentially air valves that shut off airflow in the event of a fire. They’re normally installed at any point where your system’s ductwork passes through a wall, floor or other fire-rated partition. The idea is to close off HVAC ventilation for any area where a fire exists. So, locating them within a fire-rated wall, for example, retains the integrity of the wall even if the ductwork falls away or is damaged by fire.
There are two basic types of dampers: fire and smoke. Fire dampers are usually triggered by a physical device such as a fusible link. Once the temperature rises above a specific point, the fusible link will melt and trigger the closing of the fire damper. As its name suggests, the damper’s main function is to stop fire from spreading through the ductwork.
Smoke dampers are part of the smoke suppression system. They typically connect to fire alarm systems, which trigger the dampers to close and prevent smoke transference. There are smoke/fire combination dampers as well.
Most fire codes require fire and smoke dampers to be actuated and tested every few years, depending on the facility type. Make sure you know your fire code and test that your dampers are physically working, installations are compliant and any replacements are compatible with your system.
3. AHU Support and Location
In the event of a fire, your alarm system should shut down any air handling units (AHUs) within the affected area or site wide. Again, the purpose is to contain the movement of smoke and air, and your AHU is the central place where this happens. However, operation isn’t the only consideration.
AHUs are large, heavy pieces of equipment weighing several tons depending on the size of the system. They’re also loud; that’s why they’re usually located within mechanical rooms and building rooftops. In multi-storey properties, these behemoths can become a danger to building inhabitants. During a fire, walls and floors weaken under intense heat, and those supporting heavy AHUs can give way quickly. While there’s little you can do to predict heat intensity during a fire, you can ensure your AHUs are appropriately located and that building floors are rated for their weight and size.
Conclusion
To function correctly, building systems must work together. It’s not enough just to tackle preventative maintenance for one system and ignore another. Their intertwining requires awareness of how changing one system affects another. Your HVAC system is no different. Upkeep and maintenance of it directly affects the effectiveness and efficiency of your fire protection system.
The COVID pandemic increased awareness and use of relatively new decontamination methods for medical facilities. In addition to standard surface cleaning and disinfection, hospital managers employ vaporized hydrogen peroxide (VHP) systems within negative pressure rooms to eliminate SARS-CoV-2. Sometimes referred to as “Deprox,” these systems distribute a mixture of hydrogen peroxide and water within a room. The mixture is small enough to decontaminate areas that are too difficult or impossible to clean by hand.
However, VHPs must work in conjunction with HVAC systems to be safe and effective, and most functional descriptions put strict limits on an HVAC’s operation during decontamination. Use the following information to guide your design when connecting to VHPs.
HP Vapor vs Aerosol Systems
There are two methods for dispersing hydrogen peroxide (H2O2) for airborne disinfection. One is vapor phase hydrogen peroxide (VPHP) and the other is aerosolised hydrogen peroxide (aHP). The main difference being the size and concentration of the hydrogen peroxide as it leaves the system. VPHP systems produce much smaller particles and at higher concentration than aHPs. They are much closer to a gas than aHPs, which are more of a “fog” ranging from 5 and 20 μm in size.
Exposure Limits
Both VPHPs or aHPs require some downtime for operation and room exposure levels to return to normal. Decontamination cycles may take up to three hours to complete. Exposure to hydrogen peroxide vapor can be harmful, resulting in irritation to the eyes, nose and throat. The OSHA standard for permissible exposure limits to H2O2 is 1 part per million parts of air (ppm) averaged over an eight-hour work shift.
Functional Descriptions
Include these sections when writing a FD that includes VPHP or aHP for negative/positive pressure rooms.
Room Modes—Room modes include isolation, deprox and standby. During the deprox process, the HVAC system should be turned off and dampers closed to ensure the VHP system works effectively.
Closing Dampers—When switching from standby or isolation to deprox mode, factor in a lag time to allow dampers to fully close. For example:
If the room is switched to deprox mode, the deprox LED will flash on and off for 75 seconds whilst the room dampers are driving closed. Once the 75 seconds have passed, the LED will be enabled.
Velocity Pressure Setpoint—Include a deprox pressure setpoint when setting duct velocity pressure points.
If the room is put into deprox mode, the velocity pressure setpoint is reduced to the deprox velocity pressure setpoint (To be determined at time of commissioning).
Smoke and Fire Detectors
Particles from VPHP or aHP can set off fire and smoke detectors. Consider the implications for your HVAC system. Since HVAC systems are normally integrated into fire systems to ensure proper exhaust of smoke, a false alarm may affect your system.
Colder weather often brings spikes in COVID-19 and influenza cases. With this in mind, we should continue promoting vaccinations, mask wearing, social distancing, surface cleaning and handwashing inside your buildings. However, we shouldn’t forget about our HVAC systems; they also play an important role in stopping the spread of COVID. In fact, if not properly managed, these systems significantly contribute to virus transmission. To properly protect your facility’s visitors and workers this winter, prep your HVAC system the right way by following these guidelines.
Use an Air Dilution Strategy
Viruses like SARS-CoV-2 travel within tiny liquid droplets expelled through our coughs and sneezes. These droplets can range in size from larger particles (5-10 μm) to smaller ones (less than 5 μm). Larger droplets fall to the ground quickly, while smaller aerosols linger in the air much longer. Their hang time presents both a problem and an opportunity. The problem is that these tiny airborne particles can easily cluster together, becoming concentrated within small areas like offices. Concentration makes them more potent and contagious.
However, these clusters are also easily dispersed or “diluted” by adequate air flow. So, an effective dilution strategy is to keep a good mixture of air within every part of your building. It’s a similar idea to running vs standing water. Which is safer to drink? Here are some tips for an effective dilution strategy.
Increase Outside Air Flow
Increasing outside air flow helps dilute recirculated interior air and break up any high concentration particle clusters. The CDC recommends the following tips when introducing outside air flow into your interior spaces:
Disable demand-controlled ventilation (DCV) systems
Open outdoor air dampers beyond minimum settings
When conditions allow, open windows and external doors
Use stand-alone fans inside windows
Set indoor AC unit fan speeds to “on” instead of “auto”
Run your systems longer, 24/7 if possible
CAVEAT: Increasing outside air flow during very cold or very warm weather raises your energy costs and puts added stress on your system to maintain set points. So, some actions may only be practical during milder weather. Another concern is the introduction of pollutants and pollen into the building. For occupants with allergies, outside air could contain possible health risks from contaminants. Increasing outside air flow during very cold or very warm weather raises your energy costs and puts added stress on your system to maintain set points. So, some actions may only be practical during milder weather.
Another concern is the introduction of pollutants and pollen into the building. For occupants with allergies, outside air could contain possible health risks. Most higher-rated filters can catch pollen (which is between 5 -11 μm) so introduction of outside air through fans, open windows and doors pose the greater risk.
Target 5 Air Changes Per Hour
Your air change rate (ACH) is a measure of how often you replace the air within a space. However, ACH is a bit misleading since one cycle doesn’t equate to 100% removal. In fact, it takes longer than you’d expect to vacate any contaminants from a room.
“When we change air in a room,” explains Lance Jimmieson, of Jackson Engineering, “we’re not magically taking out all of the air that’s there and replacing it with fresh air. It comes in, mixes and turns over, and typically mixes between perimeter and center zones. So, we’ve got to remove it.”
Jimmieson advises targeting a minimum of 5 air changes/hr (12 cycles) and bases his recommendation on CDC data (Table B.1). “Even with ten air changes an hour, i.e. every 6 minutes, it’s still going to take half an hour to get rid of any traces of an aerosol in the room, so air change rates need to be relatively high,” he explains.
The choice of filter matters when trying to arrest droplets containing small contaminants like viruses. ASHRAE recommends a minimum MERV-13 grade or better for commercial buildings. MERV-13 through 16 can achieve a 95-99% average removal efficiency for particles from 0.3 to 1.0 μm.
High Efficiency Particulate Air (HEPA) filters have an even higher performance, capturing 99.97% of particles with a size of 0.3 μm. However, their superior efficiency creates more pressure drop in your system, which will reduce airflow rates and therefore system performance.
CAVEAT Pressure drops from upgrading filters can have a significant impact on your HVAC system. In fact, most managers and owners will find it too difficult or impossible to retrofit their HVAC systems with HEPA filters without a costly or significant redesign. This hurdle is why ASHRAE recommends using portable systems with HEPA filters. Also, higher grade filters are costly and single use, so expect an uptick in operating costs.
Consider UV Germicidal Irradiation
Ultraviolet germicidal irradiation (UVGI) systems use short wavelength UV-C light to kill viruses and bacteria before they’re distributed by your ventilation system. UVGI systems for HVAC are usually mercury-based lamps or LEDs. As viruses pass through the HVAC system, the lamps “inactivate” any viruses captured by high efficiency filters or that move through the AHU.
UVGI lamps contribute to air sterilization, especially where outside air flow is restricted and/or dilution efforts are insufficient. However, UV-C does have limits. Jimmieson notes that one critical restriction that’s often overlooked is particle size. “By and large, a good rule of thumb is that if you’ve got a particle size that is bigger than 5 μm then you’re going to struggle to nuke that particle with UV light.”
It’s a fact that has implications for your filtration system, since low efficiency filters allow particles greater than 5 μm to pass through. If those larger particles are hosting viruses, then they may not be neutralized by your UVGI. “You really want to position the UVGI system downstream of a good quality filter to take the lumps out of the air,” Jimmieson recommends.
