Interior lighting design

Overview

Light one room at a time. Give it an outline, a ceiling height, how reflective the surfaces are and the luminaires (a maker's .ies or .ldt file, or a generic type to try it), and it works out the lux on the workplane, the uniformity, glare (UGR) and watts per square metre, with the light that bounces off the floor, walls and ceiling included. Add windows and it gives a daylight factor under the standard overcast sky. List furniture and partitions and they block the direct light. Draw an escape route and it checks the emergency lighting on the floor.

It works in CadCraft (rooms from closed shapes, results drawn on layers) and in BimCraft (rooms and windows from the model, luminaires placed as light fixtures in the room's level, lux written into the plan view). The numbers are a design aid, not a certificate: the person responsible for the lighting design checks the result.

Who it’s for

• An electrical designer or architect who wants to check that a room reaches its target lux and uniformity before choosing luminaires.
• An interior designer comparing luminaires or window sizes for a room.
• A BIM user who wants real light fixtures in the model, scheduled with their wattage, and the calculated lux on the plan.
• A lighting engineer who wants a quick first pass before a full simulation program.

What you can do

• Plan the fewest luminaires, in an even grid, that reach a mean lux and uniformity you type; or place a grid or rows yourself. Layout section.
• Read mean, lowest and highest lux on the workplane, uniformity, wall and ceiling lux, UGR and watts per square metre, with a colour map. Calculate.
• Check the result against typical requirements for 15 kinds of room, or your own numbers. Requirements section.
• Add windows (wall, position, size, glass) and read the daylight factor and its spread. Windows and daylight section; in BimCraft the model's windows fill in when you pick a room.
• List boxes (furniture, columns, partitions) that block direct light. Furniture and partitions section.
• Check emergency lighting along an escape route and over the open area. Emergency lighting section.
• CadCraft: draw the luminaires and the lux values on layers LD-LUMINAIRE and LD-LUX (one undo). BimCraft: place them as IfcLightFixture in the room's level and draw the lux as numbers in the plan view (undo steps).
• Print a report page (with a map, requirement checks, daylight and emergency results) or save every grid point as CSV.

Methods and standards

Direct light is the inverse-square cosine law on the luminaire's own candela table (.ies or .ldt). The room's surfaces are cut into patches, each a matt reflector with the reflectance you give; the light that bounces between them is solved with a radiosity iteration (disc form factors, rows scaled to one, Gauss-Seidel). The workplane grid is spaced by the rule of EN 12464-1. Glare is the CIE 117 UGR formula as an estimate. All lux are maintained values (light loss factor, 0.8 by default).

Daylight uses the CIE standard overcast sky, whose luminance is Lz (1 + 2 sin g) / 3 at altitude g, so an unobstructed horizontal plane gets 7 pi / 9 times Lz. Each window is cut into small cells; a point receives T times the sky luminance times the two cosines times the cell area over the distance squared from each cell; directions below the horizon give nothing. The light that comes in is added to the patches and bounced like electric light. Furniture and partitions are boxes; a luminaire reaches a point only if the straight line crosses no box (a slab test); bounced light is not blocked. Emergency lighting is the direct floor illuminance from the luminaires on the emergency circuit at their emergency output, along the route's centre line and over the open area, reflections ignored.

Data and sources

It ships five synthetic luminaire types (not a maker's) and typical requirement numbers for 15 kinds of room and for emergency lighting. Those numbers were typed from memory of EN 12464-1 and EN 1838, are not checked against any edition and wait for a lighting engineer to confirm them; each can be typed over. It reads .ies and .ldt photometry files you load. The room comes from your drawing or model; nothing is sent anywhere.

Verification

Limits

It is a design aid, not a certificate, and nobody has compared a result with DIALux or another lighting program on the same room. Walls do not block light from each other, so a room that is not a box reads a little too bright in its bays; furniture you list blocks direct light only. Daylight has no sun, clear sky, ground reflection, buildings or trees outside, the same glass transmittance at every angle and no frames. The requirement numbers for rooms (EN 12464-1 style) and for emergency lighting (EN 1838 style) are typed from memory, unverified, and waiting for a lighting engineer; never read them as the standard's. Emergency lighting counts direct floor light only: no signs, duration or switch-over time. UGR is an estimate not compared with a published table. Not built: isolines, a 3D picture, a maker's catalogue, exterior and road lighting. The BimCraft window height is assumed 1.2 m and the room's ceiling height is the walls' usual height. The SuperCad Studio adapter is not built.

Files and formats

Reads IES and EULUMDAT (.ies, .ldt) photometry files. Writes an HTML report, a CSV of the grid, drawing entities in CadCraft (layers LD-LUMINAIRE and LD-LUX), and in BimCraft IfcLightFixture elements (CadCraft_Electrical and CadCraft_LightDesign property sets) and drafting lines in the level's plan view.

Get started

1. Switch the add-on on in Settings, Add-ons, then open the Lighting design tab.
2. Pick a room (CadCraft: select a closed shape and press Read again; BimCraft: choose one of the model's rooms) or type the outline, then set the ceiling and workplane height.
3. Choose a luminaire, plan for a target lux, press Calculate, and read the numbers; add windows, boxes or an escape route when the room needs them.
4. Press Draw in the drawing to put the result in the drawing or model, or Report for a printable page.

Languages

The text is available in:

• Afrikaans (af)
• Amharic (am)
• Arabic (ar)
• Azerbaijani (az)
• Belarusian (be)
• Bulgarian (bg)
• Bengali (bn)
• Bosnian (bs)
• Catalan (ca)
• Czech (cs)
• Danish (da)
• German (de)
• Dhivehi (dv)
• Greek (el)
• English (en)
• Spanish (Spain) (es-ES)
• Spanish (Mexico) (es-MX)
• Estonian (et)
• Persian (fa)
• Finnish (fi)
• Filipino (fil)
• French (fr)
• Galician (gl)
• Guarani (gn)
• Hebrew (he)
• Hindi (hi)
• Croatian (hr)
• Hungarian (hu)
• Armenian (hy)
• Indonesian (id)
• Icelandic (is)
• Italian (it)
• Japanese (ja)
• Georgian (ka)
• Kazakh (kk)
• Khmer (km)
• Korean (ko)
• Kyrgyz (ky)
• Lao (lo)
• Lithuanian (lt)

Works in

Comes with

Nothing else.

Permissions

• Adds a panel section
• Opens or saves its own file types
• Keeps its own settings in this browser
• Adds commands

From its manifest. Shown again when an update changes them, and the update waits for your yes.

Versions

Licence and maker

CadCraft (CadCraft, first-party). Licence: Apache-2.0. Dependencies carry their own licences, listed on their pages.