Lighting Design: Examination of Full-Spectrum Term Paper

This lighting component is connected by the "IR receiver/sensor to the dimming ballast...[which]...provides the control to change the lamp's lumen output." (Richman, 2005)

Another lighting system introduced by Knisley is one that "features a manual override of automated fluorescent lighting settings through use of a wall-mounted control, an infrared handheld remote control device, or a PC workstation." (Knisley, 2005) This system is capable of implementing natural daylight where available which is known as "daylight harvesting" and a strategy which utilizes "ceiling-mounted photocells to measure the changing contribution of daylight and then compares this light level to an established level of light in a room. The controller responds by dimming or brightening the fluorescent lighting to sustain the desired level. The controller is compatible only with specific manufacturer's electronic fluorescent dimming ballasts." (Knisley, 2008) Knisley describes yet another system which combines "fixtures, user controls, and digital communications and as an alternative to circuit enabling group control of fixtures the groups are established "by address and controlled with a group controller." (Knisley, 2005) Options for wall controls are in a range starting with very simple "group dimmers or broadcast controls to programmable scene controllers." (Richman, 2008) Control software for the computer that enables digital controllable ballasts in ceiling-mounted fixtures is also available. Included in system features is individual occupancy control of assigned fixtures, standard lighting control functions, logging of fixture operating levels and reporting of lamp and ballast failures." (Knisley, 2005) Richman states that Florescent lamp dimming that uses electronic ballast is accomplished in three ways as follows: (1) 0-10VDC analog, phase control analog, or digital control; (2) 0-10VDC - analog control system most commonly used presently and has a group of fixtures that are connected to the control circuit to receive the same command signal, allowing the control to extend beyond a single power circuit layout; (3) Phase control technology - Richman states that this is ideal 'for an architectural lighting scheme in a smaller space, such as a conference room or an individual office.' Generally, a phase control dimming ballast uses the same pair of conductors for power and control, thus providing for a simple cost-effective retrofit where control from a single location is desired; and (4) Digital Control System - this send digitally encoded pulse signals free from noise or radio frequency interference and improves the reliability of signal and control flexibility. (Richman, 2005)

The Lighting Research Center states that full-spectrum lighting describes electric light sources "that simulate the visible and ultraviolet (EV) spectrum of natural light." (2005) the Lighting Research Center states that full-spectrum is "not a technical term, but rather a marketing term implying a smooth and continuous spectral power distribution (SPD) without the spikes and troughs in radiant energy common with most discharge light sources. Full-spectrum products are usually marketed as electric light sources that emulate natural daylight; the explicit or implicit message is that 'natural' daylight is always better than 'artificial' electric light. Some full-spectrum light sources are also marketed as emitting ultraviolet (UV) radiation, as well as visible." The following figure demonstrates the SPDS of two electric light sources claimed to be full-spectrum, the Duro-Test Vita-Lite 5500 fluorescent lamp and GE Reveal 60W incandescent lamp, as well as daylight at 5500K correlated color temperature (CCT). Daylight has smooth SPD without sharp spikes or dips, whereas the claimed full-spectrum lamps that have SPDs that differ form daylight and from each other." (2005)

Spectral Power Distribution Comparison

Lighting Research Institute (2005)

Because the full-spectrum lighting is much more costly than others it is important that benefits be understood from using this type of lighting system. The Lighting Research Institute states the following benefits from full-spectrum lighting:

Improves color perception;

Improves visual clarity;

Improves mood;

Improves productivity

Improves mental awareness

Improves retail sales

Improves plant growth

Improves results of light therapy in treating seasonal affective disorder (SAD)

Improves results of light therapy for sleep disorders

Improves scholastic performance of students

Improves vitamin D synthesis in the body

Reduces incidence of dental decay (Lighting Research Institute, 2005) survey was conducted by the Lighting Research Institute in 2003 in order to assess "252 lighting specifiers, including electrical contractors and facility managers were asked 'Compared to other types of lighting, please indicate how you think full-spectrum light sources impact the following..." As shown in the following figure.

Perceived Benefits of Full-Spectrum Light Sources Among Lighting Specifiers

Lighting Research Institute (2005)

The respondents to the survey supported full-spectrum lighting benefits with fifty percent claiming that this type of lighting system had a positive effect and positive response was given by eighty-six percent who responded positively to color perception benefits.Dental health was stated to have positive effects by less than twenty percent of respondents in the survey. Across the range of benefits only a mere four percent of respondents claimed some type of negative impact. Overall, full-spectrum lighting is being adopted and the industry is thriving according to the Lighting Research Institute." (Lighting Research Institute, 2005) the Lighting Research Institute states that visual performance is not actually improved using full-spectrum lighting "under most circumstances" therefore "lumen for lumen...full spectrum light sources are...no better than any other light source." However, it is related in the report that full-spectrum lamps may provide the perception of "brighter architectural spaces than other lamps." (Lighting Research Institute, 2005) This is attributed to the high correlated color temperature (CCT) of 5000K - 7500K of the full-spectrum lighting sources. Further, the full-spectrum light has "color rendering properties meaning that surface colors will appear more saturated. Greater saturation will also give the impress of greater brightness." (Lighting Research Institute, 2005) Finally the full-spectrum florescent lamps produces UV radiation that has a "fluorescing, brightening effect on textiles and paper that have been treated with whitening agents. These combined effects on brightness perception may indeed have positive impact on building occupants, but greater perceived brightness can also be a liability, depending upon the expectations of the space's occupants." (Veitch and McColl, 2001; as cited by the Lighting Research Institute, 2005) Full spectrum light is also stated to not provide health benefits because research conducted recently has provided empirical evidence of circadian cycles in the sleeping and waking cycle of the human being which involves mental awareness, mood and immune system effectiveness all linked to daily patterns of sleeping and waking. The Lighting Research Institute states: "Light is the most important environmental stimulus for regulating these circadian cycles and synchronizing them to the solar day. Short wavelength (blue) light is particularly effective at regulating the circadian system; long wavelength (red) light is apparently inconsequential to the circadian system. Thus, to maximize efficiency in affecting the circadian system, a light source should not mimic a full spectrum, but instead should maximize only short wavelengths. Even if a full-spectrum light source includes short wavelength light in its spectrum, it will not necessarily ensure proper circadian regulation because, in addition, the proper intensity, timing, and duration of the light exposure are all equally important for satisfactory circadian regulation..." citing Rea et al. (2002). However, the psychological benefits to full-spectrum lighting are noted significantly and "particularly in societies that place value on 'natural' environments." The benefits of individual control systems allow individuals in different "latitude are relating to: "...latitude, time of day, season, and so forth" to accommodate the day as natural light does not have a fixed spectrum. Psychological benefits include positive affect in individuals relating to mood and motivation realizing an increase in employee productivity and retail sales. While these benefits are noted there has not been found to be a "...biophysical explanation for these observations" (Heschong, Wright and Okura, 2000; as cited in Lighting Research Institute, 2005) Even so, the Lighting Research Institute states the following: "Still, the power of psychological associations cannot be denied and it is certainly conceivable that cleverly marketed full-spectrum light sources may provide beneficial effects to some people susceptible to that marketing. As NLPIP's survey demonstrated, there appears to be a strong positive association with full-spectrum light sources that has resulted from marketing, presumably because of the association between full-spectrum lighting and "natural" light." (Lighting Research Institute, 2005) Harmful effects are noted in the Lighting Research Institute series which is interestingly that there is no harm caused the human by UV radiation in ultraviolet lighting but architectural items such as materials and cloth are notably affected by UV lighting. In terms of how one would identify the most effective full-spectrum lighting source, the Lighting Research Institute states: "Formally then, the proposed reference full-spectrum light source is an ideal light source with equal energy across the visible region of the spectrum, from 380 to 730 nm, inclusive." (Lighting Research Institute, 2005)

METHODOLOGY

The methodology employed in this study is one of a qualitative nature and will be through a review of literature in this area of study. Literature will be reviewed for the….....