Evaluation and Optimization of Interior Circadian Daylighting Performance for the Elderly in Traditional Dwellings: A Case Study in Western Hunan, China

With the implementation of China’s rural revitalization strategy, the sustainable preservation of traditional dwellings has become a research priority. Moreover, with the aging population in the countryside increasing, the limited mobility of the elderly may result in them receiving daily corneal illuminance too low for a healthy circadian stimulus. This work aims to explore the relationship between circadian and daylighting design parameters inside traditional dwellings and to develop easy-to-use methods for guiding indoor circadian design in traditional dwellings in western Hunan. Additionally, it seeks to promote the digitalization and informatization of traditional dwellings in western Hunan for preservation purposes, aiming to integrate these efforts with sustainable tourism and community development, which supports the local economy while preserving cultural heritage. The main contributions are as follows: (i) Systematic evaluation of the indoor lighting and circadian status of traditional Miao dwellings in western Hunan. (ii) Simplification and application of the CS and corneal illuminance fitting model for guiding circadian design, especially suitable for indirect indoor circadian aspects of lighting in daylight scenarios. The simplified model provides quick circadian design feedback and promotes healthy circadian concepts. Its accuracy has been verified by fitting it with simulation data from Climate Studio daylighting software. (iii) Exploration of daylighting conditions using simulation software, focusing on ρ′ (the area-weighted average of room surface reflectance), ρ (the reflectance of the surface where the first reflection occurs), and the WWR (Window-to-wall ratio) in two different types of traditional dwellings. This also includes defining the dwelling parameter intervals necessary for an appropriate circadian stimulus in traditional Miao dwellings in western Hunan. (iv) The analysis suggests that enhancing ρ′ has a greater effect on circadian lighting than WWR, indicating that increasing ρ′ should be the preferred method for achieving high-quality and efficient circadian lighting.