Building Energy Savings by Tuning Indoor Lighting

Lighting plays an important role in non-visual responses in areas such as physiology, psychology, cognition, sleeplessness, alertness, and work productivity. Among the various possible non-visual responses, there is a long-held belief that warm-colored lighting induces feelings of warmth, while cool-colored lighting produces the opposite effect, which was first proposed in 1926.

In theory, if lighting could adjust human thermal sensation levels, it can serve as a possible tool for building energy savings by allowing heating and cooling temperature settings to vary over a wide range, and hence reduce building energy use. Particularly, light-emitting diodes (LEDs) are revolutionizing the lighting domain because they offer a number of unique advantages, including almost full control of their spectra and a vast intensity of responses. With the ability to tune lighting spectra and intensity, even small effects on temperature perception may achieve significant energy savings over the long term. Our preliminary simulation indicates that the potential energy savings by widening 1°C cooling and heating thermostat setpoints could be about 15%. There have been a few prior studies on the hue-heat perceptual interaction, but the conclusions drawn in these studies are ambiguous and controversial.

This research team proposes to establish a new thermophysiological model of indoor thermal perception to electrical lighting and develop a visually-integrated thermal comfort (ViTCo) building control system for tuning indoor lighting SPDs with specific timing and durations for achieving building heating and cooling energy savings. As a step toward this research goal, the research objectives of this seed fund proposal are to collect preliminary evidence about effects of light on thermo-physiological responses and initially design the ViTCo control scheme.

Resulting Publications


Javad Khazaei

Javad Khazaei
Former Assistant Professor of Electrical Engineering, Penn State Harrisburg

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