Daylight quality: high-transmittance glass versus low transmittance glass - effects on daylight quality, health, comfort and energy consumption

Effects of dim-evening lighting optimised for geographical orientation versus standard lighting on mental health: protocol paper for a quasiexperimental study in a psychiatric hospital

INTRODUCTION

Research has provided novel insights into how light stimulates circadian rhythms through specialised retinal ganglion cells to the suprachiasmatic nucleus. In addition, there has been a revolution in light-emitting diode (LED) technology, leading to tunable LED light sources and lighting systems, enabling 24-hour dynamic light scenarios with bright blue-enriched short wavelength light during the day and dim evening light, stimulating the circadian system. These dynamic LED lighting systems are now being implemented at hospitals without adequate understanding of how it may affect the health and well-being of patients and staff.

METHODS AND ANALYSIS

An optimised dynamic LED lighting scenario is investigated at a newly built psychiatric hospital in Copenhagen. In the 12 months baseline period, a standard lighting scenario with dynamic colour temperature and fixed light intensity is investigated. In the following 12-month intervention period, a new DEL scenario is investigated, having dynamic colour temperature as well as dynamic light intensity with a higher daytime and lower evening-time melanopic daylight equivalent illuminance. This setting is furthermore adjusted for geographical orientation to compensate for differences in sunlight access in wintertime. The study uses a quasiexperimental design comparing patients admitted in the two study periods. Prior to each of the study periods, daylight and the contribution from the LED-lighting scenarios was measured. Patient sociodemographic and mental health data will be retrieved retrospectively from electronic medical records and by questionnaires administered in the two periods, evaluating lighting, noise, sleep quality and quality of life. Primary outcome is the proportion of patients receiving pro re nata medications. Secondary outcomes are the length of stay, sleep onset latency, sleep quality and quality of life.

ETHICS AND DISSEMINATION

No ethical issues are expected. The results will be disseminated through peer-reviewed international journal, lectures, posters and interviews.

TRIAL REGISTRATION NUMBER

NCT05868291.

Indoor environmental quality in schools: NOTECH solution vs. standard solution

Background

In many Danish schools, the indoor environmental quality (IEQ) is challenged and studies document a poor IEQ in a majority of existing schools. Municipalities cannot afford comprehensive renovations and expensive mechanical ventilation solutions, hence public schools often suffer from poor indoor environment conditions. This study tests a new façade based, demand-controlled ventilation solution called NOTECH in the renovation of school. The study tests NOTECH vs. existing mechanical ventilation solution, comparing performance of both solutions at Skovbrynet Skole in Denmark.

Methods

The project investigates the effect of the NOTECH solution in a primary school classroom, comparing it to a similar classroom with conventional, mechanical ventilation. Methodically, indoor environmental quality and energy performance is monitored in the two identical classrooms during one school year 2018 - 2019.

Results

The results show that both systems keep the conditions within acceptable limits and CO2 levels below 1000 ppm, which is the requirement according to the Danish Building Regulations. In terms of costs, the NOTECH system has a lower overall cost than the mechanical ventilation system, with total estimated costs for installation, heating, electricity and maintenance amounting to approximately 35% of the mechanical system's costs. Finally, the results show that the NOTECH solution has a smaller embedded CO2 footprint for building materials, reducing the estimated carbon load by 95% compared to the mechanical ventilation solution.

Conclusions

While the performance of the both systems complies to the Danish Building Regulations, the indoor environmental quality between systems differs significantly. Results showing a higher air-temperature and lower relative air-humidity in the classroom with mechanical ventilation during winter and lower CO 2 levels in the mechanically ventilated classroom during winter and summer. Costs for implementation, energy consumption for heating and CO 2 footprint for building materials are significantly lower for the NOTECH solution, compared to the mechanical solution.