Electric Lighting + Personal Control

I. Personal Control of Lighting System

As designers and building engineers implement energy saving control systems it’s critical to understand occupants’ preferences prior to installation in order to maximize savings and occupant satisfaction. A study by Sara Gilani and William O’Brien found that users in perimeter offices preferred some level of manual control over their lighting systems in order to maximize available daylight. With this information, they conducted a study where vacancy sensors (manual-on / auto-off) were installed in place of existing occupancy-based sensors in these offices and found that lighting electricity use was reduced by a factor of seven. Not only was this small change able to further reduce energy consumption, but it also increased the employees’ satisfaction since this is their preferred control method.

A separate study by Newsham et. al. found that the ability to control lighting and flow rate of ventilation based on individual preferences led to greater satisfaction with the office environment. Not only did the controls lead to higher satisfaction, but they found that individual preferences actually led to an increase in energy savings. Over the course of a day, their study revealed two to three control actions from users, but in a long-term pilot study (several months) those actions reduced to just one control action per person per day. Lastly the study found that during load-shedding situations, those with personal control were less affected compared to the participants with no personal controls.

A comprehensive report put together by Alison Williams, Barbara Atkinson, Karina Garbesi, and Francis Rubinstein of Berkeley National Lab synthesizes energy-savings data from 240 saving estimates found in over 88 papers and case studies. The collected data was categorized into daylighting strategies, occupancy strategies, personal tuning, and institutional tuning. In conclusion they were able to provide best estimates of average energy savings potential for occupancy, daylighting, personal tuning, institutional, and when multiple strategies are employed simultaneously. They found that personal tuning resulted in 31% energy savings alone. In order to achieve the highest energy savings potential they recommend utilizing more than one method.

II. Controls-Based Lighting Systems

Myer and his team conducted an in-depth evaluation of five advanced lighting control systems in a working office environment. The case study was designed to evaluate the capabilities of these advanced technologies and highlight their positive and negative attributes, instead of simply comparing one product with another. The evaluation was not only concerned with the energy savings performance, but other critical aspects of the system such as occupant satisfaction, installer experience, and overall system operation. The case study found: that the systems achieved an average energy savings of 63%, installers found the installation on par or easier than traditional lighting, and occupants expressed over 70% satisfaction with the systems. 

Richman and McIntosh of The Pacific Northwest National Laboratory (PNNL) compiled a similar report after conducting in-field evaluations for five different advanced control LED lighting systems. These evaluations occurred between November 2015 to September 2017 and were meant to provide data and information to help inform those responsible for energy use and savings at commercial facilities – not a direct comparison between systems. In addition to evaluating the systems, they also conducted pre- and post-retrofit surveys with building occupants and installers. Overall they found average energy savings to be around 66% and general satisfaction with system to be around 84%.

In Michelle Davidson’s evaluation of a warehouse case study where an advanced lighting control system was installed highlights the significant impact a lighting control system can have on the entire operations of a business. Despite the 200,000 sf facility being only 3-years old, its lighting fixtures were consuming over 1.3 million kWh each year. With the implementation of LED fixtures and an advanced lighting control system, the facility was projected to save roughly 500,000 kWh per year, however, since 2013 the building has averaged an annual consumption of 300,000 kWh – exceeding their savings projections. The lighting control system has also enabled the company to monitor space utilization, which ties into their HVAC system to optimize heating and cooling schedules. The lights are also able to track equipment usage, which has improved maintenance schedules and improved the efficacy of their operation. As technology continues to advance, lighting controls offer a unique opportunity for businesses that extend beyond energy savings.

The post-occupancy case studies reviewed by Doulos et al. revealed the importance of understanding the human factor as you design the lighting, both natural and artificial, within a space. Leveraging lighting control systems that react to the available daylight within a space is a great way to save energy, while maintaining a high-quality visual environment, but it’s important to conduct post-occupancy evaluations to determine overall satisfaction with the controls. Their study found that age impacted overall visual satisfaction, with older users preferring more light than younger users. However, the common theme among users was that natural daylight is preferred and all electric lighting control system should have a manual override that allows users to switch it on and off at will.

III. Thoughtful Lighting Design

Luenendonk’s article summarized existing literature related to the non-energy impacts on employees in the work environment. Until recently updates to office lighting were seen as an aesthetic improvement or even a reduction in energy consumption, but current research suggests that lighting has more profound – biological – impacts on those employees in the space. With this in mind it is vital that lighting is carefully considered within an office setting because the wrong choice can lead to headaches, eye strain, poor sleep quality, fatigue, and an overall reduction in productivity. In order to facilitate a healthy work environment, carefully consider the correlated color temperature (CCT) of the light source, the degree of personal control of the lighting system (i.e., can employees adjust the light output to match their needs), and when possible prioritize natural daylight.

In a study by Juslén et. al. they investigated the effect of illuminance on the speed and quality of workers assembling electronics in a factory setting. The two lighting scenarios, 1200 lux and 800 lux, were studied during both the summer and winter months to account for seasonal daylighting differences. The study found that under higher illuminance (1200 lux), there was a increase in production speed during both the summer and winter months. This is one of many studies that demonstrate the secondary benefits of a quality lighting system. 

IV. References

Primary Research

• Newsham, Guy, Mancini, Sandra, Veitch, Jennifer, Marchand, Roger, Lei, William, Charles, Kate, and Arsenault, Chantal. 2009. “Control Strategies for Lighting and Ventilation in Offices: Effects on Energy and Occupants.” Intelligent Buildings International (London) 1 (2). Taylor & Francis Group: 101–21. doi:10.3763/inbi.2009.0004.
• Gilani, Sara, and O’Brien, William. 2018. “A Preliminary Study of Occupants’ Use of Manual Lighting Controls in Private Offices: A Case Study.” Energy and Buildings 159. Elsevier B.V: 572–86. doi:10.1016/j.enbuild.2017.11.055.
• Williams, Alison, Barbara Atkinson, Karina Garbesi, and Francis Rubinstein. 2011. “A Meta-Analysis Of Energy Savings From Lighting Controls In Commercial Buildings”. Ernest Orlando Lawrence Berkeley National Laboratory. https://eta.lbl.gov/sites/default/files/publications/a_meta-analysis_of_energy_savings_from_lighting_controls_in_commercial_buildings_lbnl-5095e.pdf.
• Myer, Michael. 2018. “Evaluation Of Advanced Lighting Control Systems In A Working Office Environment”. Gsa.gov. https://www.gsa.gov/cdnstatic/Applied_Research/PNNL_Evaluation_Advanced_Lighting_Controls_11-2018.pdf.
• Doulos, Lambros T, Tsangrassoulis, Aris, Madias, Evangelos-Nikolaos, Niavis, Spyros, Kontadakis, Antonios, Kontaxis, Panagiotis A, Kontargyri, Vassiliki T, et al. 2020. “Examining the Impact of Daylighting and the Corresponding Lighting Controls to the Users of Office Buildings.” Energies (Basel) 13 (15). MDPI AG: 4024. doi:10.3390/en13154024.
• Davidson, Michelle. 2016. “Case Study: IoT Lighting System Cuts Energy Costs, Improves Productivity.” Network World. Network World. July 26. https://www.networkworld.com/article/3099682/case-study-iot-lighting-system-cuts-energy-costs-improves-productivity.html.
• Juslén, H. T, Wouters, M. C. H. M, and Tenner, A. D. 2007. “Lighting Level and Productivity: a Field Study in the Electronics Industry.” Ergonomics 50 (4). ABINGDON: Taylor & Francis: 615–24. doi:10.1080/00140130601155001.
• Luenendonk, Martin. 2019. “How Lighting Affects Productivity And Mood”. Cleverism. https://www.cleverism.com/how-lighting-affects-productivity-and-mood/.
• Richman, EE, and McIntosh, JA. 2018. “Advanced Lighting Control System Performance: A Field Evaluation Of Five Systems”. Designlights.Org. https://www.designlights.org/default/assets/File/Lighting%20Controls/DLC_Advanced-Lighting-Controls_Final-W.