On the average horizontal illuminance in rooms with one or two point light sources

ABSTRACT

To ensure high-quality lighting in indoor spaces, many objective parameters have been suggested in building codes and standards all over the world. Despite the emergence of luminance-based metrics, the average horizontal illuminance (E_av) remains popular in practice. For the case of relatively small rooms with one or two point light sources, it is often intended to determine the point with horizontal illuminance equal to E_av. It is also intended to have the computation for various room scenarios, so that the outcome can be predicted using a simple model. This study, therefore, aims to propose a method to identify the location of point of E_av on horizontal plane in cuboid rooms with various sizes, with one or two point light sources, and to further verify the theoretical concept. To achieve the objective, scenarios and assumptions are described using mathematical tools, followed with verification using grid computations and Monte Carlo simulation of 10,000 random scenarios. Logarithmic models to predict E_av value and its representative location are proposed. The room length-to-width ratio is found more influential, compared to the source luminous intensity characteristics, in affecting the location of point of E_av.

KEYWORDS:

• Room lighting
• average horizontal illuminance
• point of average illuminance
• point light source
• room length-to-width ratio

Data availability statement

The data that support the findings of this study are openly available at URL: https://bit.ly/3L3NAUs.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research is supported by the Ministry of Education, Culture, Research, and Technology of the Republic of Indonesia, through the Indonesia Collaboration Research Program (RKI) 2022.