Energy and Circadian Assessment of a Combination Between Integrative Lighting and Daylight Harvesting

Abstract

This study deals with the health and wellbeing of humans who work in offices as well as the energy use for the lighting. The focus is on how integrative lighting and daylight harvesting can be combined in an attempt to reduce the energy consumption while still eliciting a circadian response for the workers.
 
The aim of this study is to investigate a combination of integrative lighting and daylight harvesting. Besides that, the study partly aims to make a literature review on the topic with the intention to find answers for unanswered questions for previous studies. The goal on the other hand is to understand how an integrative lighting system in offices could be engineered to consume less energy that it does today, while still eliciting similar variations of melanopic over photopic (M/P) illuminance ratios.

The research methods of this report included primary research of on-site measurements and observations as well as research of literature studies. Moreover, several modelling and simulation software’s within energy and non-visual effects of light were used and analysed in order to answer the research questions.

Literature on the subject along with technical information for the chosen light source has been a central and important part of the study, Adaptive Lighting for Alertness (ALFA) was a key factor in order to achieve optimum results. The results correlate with literature and previous research as they both confirm that the circadian entrainment is affected differently by different SPDs. The study shows that a combination of integrative lighting and daylight harvesting reduces the energy consumption, while the M/P ratios were both sufficient and insufficient depending on whether it is wintertime with overcast sky or summertime with
clear sky.

Popular Abstract

In modern societies, people tend to spend up 90% of their lifetime indoors of which a big share is spent at work, this raises the demands for several aspects in terms of health and wellbeing. Several studies have proved that the quality of lighting has an impact on workers’ health and performance. There is a network of circadian clocks in mammals that are reset with help of input and circadian signals that are delivered to the brain, a master clock at the top of this network that is located in the suprachiasmatic nuclei (SCN) is mainly controlled by ambient light. Intrinsically photosensitive retinal ganglion cells (ipRGC), which works as environmental irradiance detectors which senses light levels independently without the input from either rods or cones, is a proof of the non-visual pathway that affects the human physiology and psychology. The ipRGCs are responsible for transforming the information to the SCN which is located in the brain in order to help reset the circadian clocks.

A relatively new concept called integrative lighting is investigated in this study, the concept of integrative lighting is to support the circadian entrainment by varying in intensity and correlated colour temperature (CCT) during the course of a day in order to elicit a circadian response. Most of the integrative lighting systems that are available today are designed with the intention of supporting the circadian entrainment, which has led to lost or less focus on the energy consumption of such light source despite the fact that daylighting is free, and it stimulates the circadian entrainment better than any light source that are available today. Therefore, this study aims to investigate a combination of integrative lighting with daylight harvesting.

Earlier studies have shown that integrative lighting stimulates circadian entrainment. But since there were no studies that included the energy use, the objective of this study was to understand how integrative lighting systems in offices could be engineered to consume less energy than it does today with help of daylight harvesting, while still eliciting similar variations of melanopic over photopic (M/P) illuminance ratios.

The greater part of the results is consistent with previous research as they confirm that circadian entrainment is affected differently depending on the incoming light. Nonetheless, that M/P ratios were as desired in some cases and others not. Finally, yet importantly, a combination of integrative lighting and daylight harvesting was very beneficial in terms of energy as the energy demand significantly decreased. The time of the year turned out to be of great importance as the incoming light was different during different times of the year, which had a great impact on the results.

• author: Attar, Ribhi and Al Mawla, Omar
• supervisor: Niko Gentile; Jouri Kanters; Thorbjörn Laike
• organization: Department of Architecture and Built Environment; Division of Energy and Building Design
• course: AEBM01 20211
• year: 2021
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: ALFA, Circadian Entrainment, Correlated Colour Temperature, Cortisol, Daylighting, Daylight Harvesting, Energy efficiency, Integrative lighting, Intrinsically photosensitive retinal ganglion cells, Melatonin, Melanopic Lux, Photopic Lux, Spectral Power Distribution
• language: English
• id: 9050164
• date added to LUP: 2021-06-10 10:22:37
• date last changed: 2021-06-10 10:22:37