By Gerry Cornwell, LC

Lighting is undeniably one of the most important aspects of building design, and also accounts for a significant percentage of a building’s energy consumption. Fortunately, improvements are occurring in this field that are making quality energy efficient lighting a serious possibility. The objective of a “quality” lighting design is to provide a safe and productive environment – whether for business or pleasure. This is accomplished by either a retrofit or upgrade to ensure that the appropriate quality and quantity of light is provided for the users of the space, at the lowest operating and maintenance cost. Some of the options that are now making this increasingly achievable include:

Improved technology

High Intensity Discharge (HID) lights are so efficient because they produce more light than the incandescent halogen bulb while consuming less power. The design is such that the filament of a standard light bulb is replaced with a capsule of gas. Ballasts are used to supply voltage and control the current running through the capsule. Consequently, HID lighting is ideal for industrial and street lighting and underwater illumination. Lately, smaller size HID lamps are being manufactured for office and retail applications.

Yet, until recently, options for retrofit of HID systems have been limited by the available technology. Replacing aging Mercury Vapor or Metal Halide systems with Pulse Start Metal Halide systems and with high bay T5HO lamp systems have been the primary measures. However, reliable and well-designed electronic ballasts, which were previously reserved for fluorescent lighting systems, are now available for HID lamps. In order to provide the best match for optimum performance of lamps and ballast in an HID system, the electronic ballast must:

The impact of electronic ballasts on fluorescent lighting systems has been huge: for the same light output fluorescent lighting systems now use 30-40% less power, compared with traditional lamps. Electronic HID ballasts include smart circuitry to regulate critical lamp starting and restarting processes, improve lamp lumen maintenance and lengthen lamp life. These ballasts automatically sense ‘end-of-life’ conditions in the lamp and shut down the starting process to preserve the ballast.

Integrated dimming in electronic ballasts is significantly less costly than ‘add-on’ systems. Like their fluorescent counterpart, electronic HID ballasts have the advantages of lower noise and improved system performance. They are ideal for applications using photocells and occupancy sensors that allow flexibility in system design, which was not previously practical with HID systems.

A single ballast design operates different HID lamps without compromising operating characteristics and greatly reduces restocking costs.

In addition, there are savings realized by greatly extended lamp life, reducing maintenance costs. Philips Lighting recently introduced an MH lamp rated at 30,000 hours when used with an electronic HID ballast. Conventional MH lamp systems using core and coil ballasts suffer lumen loss of approximately 30% over life (LLD = 0.7 at 40% of rated lamp life). This is due to degradation of the electrodes in the lamps. Electronic systems are delivering LLD values of 0.95; in other words, the lamp loses only 5% of the initial lumens at 40% of rated life.

Rethinking how lighting is used

In addition to using improved technology, such as electronic HID ballasts, energy savings can be made by rethinking how lighting is used. For example, significant indirect savings can be achieved by reducing the impact of lighting loads on building HVAC systems as fewer lights produce less heat and so less strain is placed on the cooling system to compensate for this. Furthermore, reducing lighting use during peak demand periods, when demand on the grid is high and electricity prices rise, is another way to increase lighting efficiency. This option is often overlooked but the benefits can be two-fold since cooling reduction costs are also significantly lowered when lighting is used more efficiently during this peak period.

Another option is to use lighting with a dimming system. There are many advantages to integrating the operation of the building lighting with other electrical loads, especially if the overhead lighting is dimmable. If a building’s lighting system consists of multiple dimmable zones that can be controlled from a central computer, the facilities manager, or an automated control system, can have near-instant control of electric demand throughout a facility. This is particularly useful in terms of responding to peak demand periods. As lighting averages 37% of typical commercial building electrical demand (US figures), reducing power to the lighting system by 25% would reduce electrical demand by 10%. Dimmable lighting allows owners and operators to adjust lighting power according to peak demand, hourly price of energy or some other utility pricing signal

In effect, these systems empower owners and operators to take control of the lighting electrical load and manage it pro-actively.

New technology and new ways of looking at how we use lighting now present building owners and users with significant opportunity to further increase energy efficiency. In addition to reducing energy costs and bills, greenhouse gas emissions are reduced, which will appeal to all concerned with issue of Corporate Social Responsibility.

Bibliography
Lighting Reference Guide, 2005, Cornwell G., Rouse, S.
Advanced Lighting Guidelines, 2003

Gerry Cornwell. L.C. is one of Canada’s leading lighting designers. He has an extensive background in professional display lighting and is an award winning independent lighting designer. He works at Energy Advantage Inc as an independent consultant as our lighting specialist.