Recessed Lighting – Planning Your Downlight Layout
There are several considerations that should be addressed when planning a recessed lighting (or downlight) layout:
- Room size
- Ceiling height
- Bulb luminosity & angle of beam
- Desired effect (relaxed/ambient or ‘task’ lighting)
When planning to install open plan recessed downlighting, divide the floor space into areas of 250 sq ft (average room size) for manageability.
Recessed Lighting Layout – Room Size
First, we must gain an accurate calculation of the size of the room in which you intend to install recessed downlighting. Room size is an important starting point because the likely number of bulbs required for adequate lighting in a given space can be calculated and used as a baseline on which later considerations can be made. In order to calculate the size of a floor space, multiply the width of the room by the length of the room.
- 5,000 lumens is the suggested optimum lighting level per 250 sq ft
- Eight 10 Watt LED bulbs will provide 5,000 lumens per 250 sq ft
Working from an average of eight 10 Watt LED bulbs per 250 sq ft allows us to make further considerations about the downlight layout, specifically regarding ceiling height and the desired lighting effect relevant to the function of the room.
Downlight Spacing Guide
As a guideline, divide the height of room by two and use that number as the measurement for the distance between downlights. For example, where a room is eight feet in height, average spacing of around four feet should be observed when installing recessed downlights. TIP: If you are unsure about downlight spacing, adopt the above average spacing strategy and install a dimmer switch. This can help to control lighting levels as necessary, without relying on spacing to create a desired lighting level.
Downlights – Ceiling Height Considerations
If we now know that a floor area of 250 sq ft can be illuminated to an adequate lighting level using eight 10 Watt LED bulbs, why do we need to consider the ceiling height? Ceiling height is relevant because the light beams of the bulbs must cross at around 30 inches above the ground – this will help to light the entire floor space while avoiding darkened corners. If we take average room height to be around 8 ft, a beam angle of 35-45 degrees should be sufficient in providing adequate blending between the light beams (this will help to avoid a situation in which individual beams create a circular spotlight effect on the ground).
Downlighting Effect – Clinical vs. Ambient
A final consideration when planning the layout of your recessed downlighting project is whether you wish to achieve a clinical lighting effect or an an ambient lighting effect. This is because the purpose of the lighting is a major factor that can increase or decrease the average recommended downlight spacing. For example, you may wish to decrease the spacing between the downlights so as to allow for a greater number of bulbs in situations such as lighting a garage in which you plan to carry out technical mechanical work. Alternatively, lighting an average sized room that is intended to be used as a snug or relaxation area may require slightly wider spacing.
The Kelvin Colour Scale…
The Kelvin Colour Scale is used to highlight whether a bulb will produce cool or warm light. Bulbs in the region of 1,000 – 4,000 Kelvin produce warm glows on a gradient towards daylight conditions at 5,000 Kelvin. For cooler clinical lighting that is ideal for use in kitchens, hallways, and other practical areas, select bulbs in the region of 6,000 to 10,000 Kelvin.