Dale K. Tiller

The performance of occupancy-based lighting control systems: A review

This paper reviews the literature on occupancy-based lighting control as a prelude to the application of sensor networks to building management. Many buildings include systems to detect occupancy and control building services. Current systems use single measurement points to detect occupancy, and there can be significant uncertainty associated with the measurement of occupancy. Long time delay and high detector sensitivity settings compensate for this uncertainty, but these diminish the savings that could be achieved with more accurate occupancy measurement. More effective control may be provided by more extensive sensing, using a network of occupancy sensors, and more extensive analysis of sensor data. The literature reviewed in this paper establishes the need for an investigation of the performance of sensor networks when used for lighting control.

The subjective response to linear fluorescent direct/indirect lighting systems

This paper characterizes human subjective response to spatial distributions of light resulting from different uplight/downlight photometric distributions. An array of pendant-mounted linear fluorescent luminaires illuminated a 12.7×7.2 m room. Eleven light settings were established at constant horizontal illuminance, which differed in the percentage horizontal illuminance contribution from the uplight and downlight components. Two studies are reported where subjects evaluated the light settings using psychophysical assessments; the first study utilized paired comparisons and the second utilized semantic differential scaling. Findings include: 1) the walls and the ceiling contributed to the perception of overall brightness when the work plane illuminance was held constant, 2) the room appeared more spacious when more light was supplied indirectly, and 3) light settings where the indirect component had a horizontal illuminance contribution of 60% or more were favoured.

Measuring the subjective response to interior lighting: paired comparisons and semantic differential scaling

Paired comparisons and semantic differential (SD) scales were used as part of a larger study assessing subjective responses to linear fluorescent direct/indirect lighting systems. Two experiments were performed under identical lighting conditions, one with each technique, yielding independent subjective response data sets for the same light settings. This article compares independent multidimensional scaling solutions from the two datasets and describes an intercorrelation analysis of the SD scaling responses. These analyses highlight strengths and weaknesses of the two psychometric techniques. Guidance is offered for applying paired comparisons and SD scales in future lighting research.

Tuning the Fluorescent Spectrum for the Trichromatic Visual Response: A Pilot Study

Abstract Results of a pilot study are presented that explored the hypotheses that brightness and color perception would be enhanced by increasing the proportion of spectral content within the 450–530-610 nm regions. Expert and naïve subjects completed a forced choice task, comparing pairs of offices illuminated at 538 lx (50 fc) with one of four different prototype lamps that varied in spectral content in the 450–530-610 nm regions. Rooms illuminated with lamps having a higher percentage of their spectral power in these regions were perceived as brighter and more colorful. Expert and naïve observers had similar responses but the experts expressed their opinions more definitively. These data suggest that the perception of brightness, color, and visual clarity are more reliant upon the placement of radiant power within key spectral regions, rather than on the magnitude of the energy within those regions. These results cannot be explained with the S/P ratio.

Validating the application of occupancy sensor networks for lighting control

A new occupancy detection sensor network was developed, commissioned and installed in two private offices: data were collected to evaluate the utility of the sensor network for lighting control. Results show that there is considerable uncertainty associated with the determination of occupancy using measurements from a single detector in a space. A sensor network reduces uncertainty, because data from other detectors provides converging information that can be used to determine if a space is occupied. Sophisticated analysis techniques can be applied to the sensor network data stream to provide improved occupancy measurement and lighting control, compared to current systems.

The Effects of Fluorescent Lighting Filters on Skin Appearance and Visual Performance

(2002). The Effects of Fluorescent Lighting Filters on Skin Appearance and Visual Performance. Journal of the Illuminating Engineering Society: Vol. 31, No. 1, pp. 40-60.

Converging Redundant Sensor Network Information for Improved Building Control

Knowing how many people occupy a building, and where they are located, is a key component of building energy management and security. Commercial, industrial and residential buildings often incorporate systems used to determine occupancy, however, current sensor technology and control algorithms limit the effectiveness of both energy management and security systems. This topical report describes results from the first phase of a project to design, implement, validate, and prototype new technologies to monitor occupancy, control indoor environment services, and promote security in buildings. Phase I of the project focused on instrumentation and data collection. In this project phase a new occupancy detection system was developed, commissioned and installed in a sample of private offices and open-plan office workstations. Data acquisition systems were developed and deployed to collect data on space occupancy profiles. Analysis tools based on Bayesian probability theory were applied to the occupancy data generated by the sensor network. The inference of primary importance is a probability distribution over the number of occupants and their locations in a building, given past and present sensor measurements. Inferences were computed for occupancy and its temporal persistence in individual offices as well as the persistence of sensor status. The raw sensor data were also used to calibrate the sensor belief network, including the occupancy transition matrix used in the Markov model, sensor sensitivity, and sensor failure models. This study shows that the belief network framework can be applied to the analysis of data streams from sensor networks, offering significant benefits to building operation compared to current practice.

Sensor Networks for Lighting Control

This paper summarizes results from a research program investigating the development and application of sensor networks to lighting control and building energy management. Commercial, industrial and residential buildings often incorporate systems used to determine occupancy, however, current sensor technology and control algorithms limit the effectiveness of these devices in both energy management and security systems. These systems rely on single measurement points to detect occupancy, and as a result there can be significant uncertainty associated with the measurement of occupancy. Long time delay and high detector sensitivity settings compensate for this uncertainty, and as a result, more energy is wasted than if occupancy were more accurately measured. A network of inexpensive occupancy sensors provides a more accurate, reliable and robust occupancy measurement, and is potentially more economical in terms of initial investment and operating costs, than single-point detection systems. We show that it may be possible with a sensor network to reduce the operating time of occupancy-based building systems by an extra 20% (compared to current systems) and that the simple payback periods associated with wireless sensor networks applied in generic small and large commercial buildings may be less than two years.© 2009 ASME

Authors’ response to AR Bean:

with considerable care to methodology (they established, for instance, that subjects were able to make consistent decisions) while the usefulness of some of the previous research on this topic is limited by incomplete experimental design. The present work provides a model for testing other, more complex, situations. Secondly, every additional example of brightness distribution preferences is useful. The goal is to answer much more general questions: for instance, ‘Why do people have lighting preferences?’, ‘On what bases do they make judgements’, ‘Are choices related to the cultural background or environmental experiences of the subjects’. The literature on perception suggests that satisfaction or pleasure due to a visual environment is a far deeper process than a purely photometric response. In order to develop hypotheses concerning our perception of the light and colour in real places we need a rich repository of observations and experimental results.

Authors’ response to P Jay

with considerable care to methodology (they established, for instance, that subjects were able to make consistent decisions) while the usefulness of some of the previous research on this topic is limited by incomplete experimental design. The present work provides a model for testing other, more complex, situations. Secondly, every additional example of brightness distribution preferences is useful. The goal is to answer much more general questions: for instance, ‘Why do people have lighting preferences?’, ‘On what bases do they make judgements’, ‘Are choices related to the cultural background or environmental experiences of the subjects’. The literature on perception suggests that satisfaction or pleasure due to a visual environment is a far deeper process than a purely photometric response. In order to develop hypotheses concerning our perception of the light and colour in real places we need a rich repository of observations and experimental results.