M/E Roundtable: Optimal Illumination
A greater recognition of building lighting and its widespread effect on a building's energy efficiency has led to a closer analysis of where-and when-light is shining...
A greater recognition of building lighting and its widespread effect on a building's energy efficiency has led to a closer analysis of where—and when—light is shining. In this month's M/E Roundtable, a group of lighting designers and engineers share some of their recent experiences with control systems and ponder their effects on design practices.
Mary Alcaraz, P.E., LC, CEM, electrical engineer and lighting designer, Ewing Cole Cherry Brott, Philadelphia
Nancy Clanton, P.E., IALD, principal, Clanton & Associates, Inc., Boulder, Colo.
Scott Easton, LC, IESNA, architectural engineer, Affiliated Engineers, Inc., Madison, Wis.
Ron Kurtz, IALD, associate and senior designer, Randy Burkett Lighting Design, St. Louis, Mo.
Jeromie Winsor, moderator
CONSULTING-SPECIFYING ENGINEER (CSE): How common are advanced lighting controls-that incorporate motion sensors, photosensors or presets-in your projects? Do you find that you need to educate the end-user on their benefits?
ALCARAZ: In our experience with commercial facility lighting design, lighting controls are becoming more accepted by owners, especially when they can be justified with associated energy savings. Occupancy sensors typically pay back in 1 to 1-1/2 years or less and are becoming common to every project we design.
The evolution to 'daylight harvesting' using photosensors is coming closer to the forefront of design. We have been specifying daylight-harvesting technology on 'green buildings,' which we have designed for the U.S. government, including a recent building at the Washington Navy Yard.
KURTZ: The application of more advanced lighting controls, in our experience, is largely dependent upon project type, scale and geographic location. There is almost always some level of education required for the end-user to better understand the advantages and value of employing such systems. It revolves primarily around first-cost issues, but can also include system maintenance, the intuitive nature of the system and hosts of other smaller technical and operational issues.
CLANTON: Currently, advanced lighting controls are not common here in the U.S., but once owners are educated about the benefits, they typically agree to include them in the design. When energy benefits are explained, owners readily embrace the concepts.
EASTON: We are also currently specifying advanced lighting controls on nearly every project for various reasons, including energy-code requirements, client criteria and complexity of the building architecture. Regardless of the motivation, these systems are usually either new to the user, or more likely, they have had a negative experience with them, so education on system benefits and application is essential.
CSE: The U.S. lags behind Europe in the use of dimmable fluorescent lighting. Have you seen more use of dimming controls recently? Are clients aware of life-cycle costs and energy savings?
EASTON: We have not seen a significant increase in the use of dimming systems for the purpose of cost or energy savings. I think a large reason is that the United States also lags behind Europe in the application of effective use of daylight. While many architectural firms are growing to embrace the concept of daylit buildings, only a few are really applying well-thought-out, successful design strategies. As carefully applied 'green architecture' advances and as the cost of dimming ballasts comes down, the use of dimming systems will likely increase, but I don't think we're there yet.
KURTZ: Fluorescent dimming is on the increase in our specifications, particularly when used with standard linear T8 fluorescent lamps. The first cost, availability and reliability of electronic dimming ballasts have significantly improved over the last few years. Compact-fluorescent-lighting [CFL] dimming specifications are also increasing, but not as quickly. The comfort level with the technology for CFLs is not as great as with the linear ballasts and there is typically a more significant first cost.
Most end-users are less aware of the benefits of dimming fluorescent lamps than they are with those for incandescent lamps. So when an application arises where dimming fluorescent lamps is suggested, there is usually an education process that will be required to understand the benefits.
CLANTON: Dimming controls are still perceived as expensive and a luxury. Again, if clients are educated in giving dimming control back to the user in addition to life-cycle cost savings, then they are generally open to the idea.
ALCARAZ: We have seen an increase in the use of dimmable fluorescent-lighting systems for health-care and pharmaceutical facility clients that require flexibility of illumination levels for specialized tasks. The costs of dimmable-fluorescent lighting systems are minimal compared to the value of the flexibility in illumination levels achieved.
We see life-cycle cost/energy savings being a design driver for dimmable lighting systems where we are trying to justify daylight harvesting for the purpose of saving energy. In our experience, government clients are more aware of the benefits of daylight harvesting and are often advocates for the use of dimming fluorescent controls where justified by life-cycle cost savings.
CSE: What are the barriers to the widespread use of more elaborate control systems? Will these barriers eventually be removed?
EASTON: Three reasons come to mind: initial costs, the perception that more elaborate systems must be more complex to operate and [the assumption] that these systems will not work as intended or at least not before experiencing several problems. The latter seems to apply largely to some clients' perceptions about occupancy sensors.
Certainly all of these barriers can be overcome. It takes educating not only the client, but also other members of the design team including contractors and construction managers. It only takes one these members with a loud enough voice to throw a control scheme right out the window. We have seen it time and again.
First cost issues
KURTZ: The largest barriers we have encountered with any control system routinely involves first-cost issues and comfort with the technology. Pressures to bring a project in on budget cause controls to be one of the first things cut or 'value engineered.' It is particularly difficult to specify energy conservation-related control systems in areas where energy costs are minimal, such as the Midwest, and paybacks for such systems exceed five years.
CLANTON: 'Elaborate' controls may not be the answer. End-users have a complex control phobia, similar to programming a VCR. The major barrier is a fear of complexity. Another barrier is a fear of losing control ... having lights turn on and off at the wrong times.
Yet, simple controls used in concert with each other to add some automatic controls but to not take away user control works well. An example of this would be to give an occupant manual dimming control ... but if the occupant forgets to turn off his light when he leaves, the occupancy sensor will turn off the lights. When automatic controls are transparent to the end-user and the end-user can change the lighting level manually in his space then controls work.
ALCARAZ: The capital costs of elaborate control systems are a barrier to their widespread use. We recently came across such a cost-prohibitive barrier in the design of an open-protocol building-automation system [BAS] specified to centralize the control of central-plant mechanical equipment, variable-air-volume controls and lighting controls.
The cost barrier will lessen over time with the laws of supply and demand. With the adoption of the new codes mandating energy saving lighting controls such as ASHRAE/IESNA [American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating Engineering Society of North America] 90.1, 1999, demand for such systems will rise and costs will eventually come down.
CSE: How have lighting controls been integrated with the controls of other building systems? Has this caused more integration in the design process between engineers of different systems?
KURTZ: With the increased capabilities of microprocessors, the Internet and digital communication, lighting controls are more frequently integrated with other building-control systems than ever before. Energy-management systems, audio/visual systems and emergency systems are all routinely interacting with the building's global and local lighting-control systems.
This has increased coordination requirements between lighting designers, engineers and other specific systems designers. However, the signaling requirements between the systems are becoming easier to manage.
CLANTON: In the past, it was crucial for the lighting controls to be controlled through the energy-management system. Now, lighting controls can work independently and yet still communicate with the building-management system. I think that a well thought out lighting-control system will do its part in saving energy. An example of this would be automatic daylighting controls for public spaces. When the HVAC is at its highest demand, the lighting controls have dimmed or turned off the lighting. Occupancy sensors also help in reducing the demand of lighting. At night, when few people are in the area, occupancy sensors turn off the lighting.
EASTON: This is a hot topic with our information-technology engineers. Currently, most low-voltage lighting-control systems operate on a daisy chain network over a twisted-pair cable, and can interface with other building systems via a dry contact closure or serial/networked-communication interface if both systems share the same protocol. A long-term goal is to have these systems configured in a star topology where all systems share a structured cabling system and communicate over the same routers, thus eliminating the need for multiple systems' backbone cabling.
CSE: What controls have you designed into your most recent projects? Has there been a particularly challenging or innovative project?
CLANTON: For high-end office areas, we have designed manual dimming in combination with occupancy sensors for private spaces such as individual offices and conference rooms. For public areas, automatic daylight dimming with occupancy sensors work together to minimize lighting loads.
The most challenging project was giving occupants in an open office area individual manual dimming controls over their ambient lighting. In addition, occupancy sensors dimmed their ambient-lighting systems when they left their work areas. The occupants loved the dimming capability and thought the occupancy sensors were not working even though they were!
EASTON: We are currently working on a project to design the lighting systems for nine buildings on a new corporate campus. We are challenging manufacturers to furnish an integrated lighting-control system, capable of incorporating every lighting-control requirement on the project and expanding with the company's growth. The most exciting part is that we are confident it can be done.
ALCARAZ: One of our recent projects, focusing on innovative use of lighting controls, is the Atlantic City Boardwalk Hall, where we interfaced an energy-efficient lighting-control system with a theatrical dimming lighting-control system to control lighting for sports and theatrical events. The interface provides the flexibility of control for the various events from a single central-control system terminal.
CSE: What are the challenges when integrating an existing light system with new controls?
KURTZ: The most notable challenges that arise are dealing with existing circuiting, demonstrating cost savings, overcoming physical constraints, changing old management habits and educating the user.
CLANTON: An existing lighting system is more difficult to control with traditional control wiring. Alternatives are infrared controls that are remote controlled. Occupancy sensors that replace the wall box switches are also easy retrofit ideas.
EASTON: One of the largest challenges is the existing circuitry and control groupings. Oftentimes, in new design, our circuiting and control methodology goes hand in hand. With existing conditions, you take what you get and find creative ways to integrate new systems.
ALCARAZ: We currently have a very large, challenging controls retrofit project in construction for the City of Philadelphia's historical City Hall building. The project is administered through the City's Municipal Energy Office and therefore only focuses on adding energy-saving technology, which makes for a challenging project in an old historic building like City Hall which has old wiring, historical architecture and historical luminaires. In addition to lighting upgrades, we are adding occupancy sensors and time switches to save over $210,000 in annual energy costs over approximately 670,000 square feet.
CSE: The ideal lighting system would seemingly offer the most energy-efficient fixtures and controls while providing adequate illumination for each task in each space. Is this a possibility?
EASTON: Absolutely, though I tend to have a little different spin on this subject. I once heard James Benya [Benya Lighting Design, Portland, Ore.] talk at a seminar about the difference between energy efficiency and energy-effective design, and it has really stuck with me. You may have the most energy-efficient tools at your disposal, but careless application of these tools will likely yield a design that is neither an effective use of energy nor adequate in providing the correct amount of illumination. Conversely, a well thought out design approach will result in very effective use of energy and visual comfort, even with less of that stellar equipment.
ALCARAZ: Designing the ideal lighting system will be a necessity for designers and engineers in the future. The competitive manufacturing product market and rapidly developing technology will make specifying the ideal system a reality. The key to successfully obtaining the ideal lighting system is to not only design for energy efficiency and adequate illumination, but also to design for a high aesthetic quality of illumination for human comfort and interest.
KURTZ: Assuming that 'ideal' is not perfect and that there may be more than one ideal solution for a project, this lighting system is not only a possibility, but is routinely designed and installed by owners and designers with enough foresight to understand the positive benefits available [with respect] to energy costs, lighting control and global environmental issues.
CLANTON: Because every occupant and task requires different lighting, the best scenario is to give people back control of their lighting. Manual dimming controls provides the ability to vary lighting levels for individual needs. Occupancy sensors that only turn off the lighting when no one is in the space will save additional energy. Daylight dimming sensors work the best in public spaces where decreases in lighting levels are usually not noticed. It is this combination of controls that are automatic but transparent and manual to give people more control. If controls are over-ridden for any reason, then they did not work.