Room Lighting Calculator (Lumen Method)

A high-precision, browser-based lighting design tool that calculates the required number of luminaires and generates an optimal grid layout using the CIBSE Lumen Method.

🚀 Features

• Real-Time SVG Schematic: Visualizes fixture placement, spacing ($S_x, S_y$), and border distances.
• Lumen Method Engine: Calculates $N$ based on target Illuminance, Luminous Flux, and Maintenance Factors.
• Automated UF Interpolation: Performs linear interpolation of Utilisation Factors based on Room Index ($RI$) and surface reflectances.
• Uniformity Check: Monitors the Spacing-to-Height Ratio ($S/Hm$) and warns if it exceeds $1.5$.
• Dark Mode Interface: Built with a modern, high-contrast engineering aesthetic.

📐 The Formulae

The calculator operates on the following core principles:

1. Number of Fixtures ($N$): $$N = \frac{E \times A}{\Phi \times UF \times MF}$$
2. Room Index ($RI$): $$RI = \frac{L \times W}{Hm \times (L + W)}$$
3. Mounting Height ($Hm$): $$Hm = CeilingHeight - WorkplaneHeight - SuspensionLength$$

🛠️ Installation & Usage

This is a portable, single-file web application. No installation or dependencies are required.

1. Download the index.html file (or the HTML code provided).
2. Open the file in any modern web browser (Chrome, Firefox, Edge, Safari).
3. Adjust the Room Geometry and Luminaire inputs in the left panel.
4. The Schematic Plan and Results will update instantly.

📋 Input Parameters

Parameter	Description	Typical Value
Length/Width	Physical dimensions of the room (m)	-
Work Plane	Height where task light is measured	0.85m (Desk height)
Required E	Target illuminance in Lux (lx)	500lx (Office)
Flux ($\Phi$)	Light output per fixture (Lumens)	3000lm
MF	Maintenance Factor (dirt/aging)	0.80

📄 License

Distributed under the MIT License. See LICENSE for more information.