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VIDEO TUTORIALS

Retail Lighting Design (SLL Lighting Design Handbook)
Retail Lighting Design
(SLL Lighting Design Handbook)

This video tutorial is the part 1 of the series of tutorials for Retail Lighting Design. The information discussed here is based on the SLL Lighting Design Handbook chapter 12.

Chapter 12: Retail lighting


12.1 Functions of retail lighting


For the retailer, lighting is an essential part of ‘setting out the stall.’ Lighting has four major roles
in retail premises. They are:

  • to attract attention

  • to send a message to would-be shoppers about the nature of the shop

  • to guide shoppers around the shop

  • to display the merchandise to advantage.

Subsidiary lighting systems are needed to provide security after closing and to facilitate egress in
an emergency (see Chapter 8). Examples of retail lighting design are available in Turner (1998).


12.2 Factors to be considered


12.2.1 Shop profile


Retail premises differ on four dimensions: price, usage, range of products and sales style. It is the
position on these four dimensions that determine the shop profile. Table 12.1 indicates the most
common shop profiles.


Table 12.1 Four common shop profiles

Shop profiles matter because different profiles have different lighting styles. Low budget shops
tend to be big box stores using high level uniform general lighting with no accent or display
lighting (Figure 12.1). Exclusive shops tend to be much smaller and use low levels of general
lighting combined with strong accent and/or display lighting on the merchandise (Figure 12.2).
Value for money and quality shops lie between these extremes, with both general lighting and
some accent lighting being used.

Figure 12.1 A budget retail store                                                                         Figure 12.2 A "high-end" retail outlet

12.2.2 Daylight or electric light


Many retail premises do not allow much daylight penetration into the shop so this question is
moot. However, in many out-of-town ‘shed’ stores, daylight may be admitted through roof
lights. The use of daylight adds an attractive dynamic element to the store.


12.2.3 Nature of merchandise


The type of lighting and the colour properties of the light sources used depend on the nature
of the merchandise. Merchandise, such as bedding, needs to be displayed in a warm, cosy
atmosphere. This calls for low light levels and a warm colour appearance. Conversely, free
standing white goods are best shown at high light levels with light of a cool colour appearance,
although when incorporated into displays simulating a home setting, lighting that looks like
attractive home lighting is desirable. Merchandise such as meat, fish, fruit and vegetables needs
lighting that emphasises whatever characteristic indicates freshness, e.g. redness for meat.
Therefore, understanding the nature of the merchandise is essential when designing
retail lighting.


12.2.4 Obstruction


Some stores, such as DIY stores, have more in common with warehouses than shops. The store
is divided into a large number of aisles and the merchandise is displayed in racks extending to
head height and above. Where obstruction occurs, it is essential that the layout of the lighting
and the merchandise is coordinated.


12.3 Lighting recommendations


12.3.1 Illuminances


Retail lighting is essentially a balance between general lighting, accent lighting and display
lighting. This balance itself depends on the shop profile. Therefore, the illuminances to be used
depend on the shop profile. For low budget shops, where there is no accent or display lighting,
the average illuminance should be in the range 500 to 1000 lx. This illuminance should be
provided on the merchandise. For a supermarket, this means on the vertical faces of the shelves.

For a shop with an exclusive profile, which means the widespread use of accent and display
lighting, the average general lighting illuminance should be in the range 100 to 200 lx. This
lower illuminance is necessary for the accent lighting to be effective and should be provided on
a horizontal plane at counter level.


For shops with value for money and quality profiles, where some accent lighting is used, the
average general lighting illuminance should be in the range 250 to 500 lx and should be
provided on the merchandise.


12.3.2 Illuminance uniformity


Regardless of the shop profile, general lighting should be uniform. An illuminance uniformity
(minimum/average) of at least 0.7 should be achieved by the general lighting alone. Where
accent and display lighting is used, the overall illuminance uniformity is low, by design.


12.3.3 Luminances


For accent lighting to be effective, the luminance of the merchandise lit has to be higher than
the luminance of its immediate background. Different luminance ratios will give different
strengths of highlights and shadows. Table 12.2 indicates the luminance ratio for different
strengths of accents.


Table 12.2 Luminance ratios for different strengths of accent lighting

12.3.4 Light source colour properties


The colour appearance of the light used in a shop will contribute to the message the lighting
sends to would-be shoppers. A cool light appearance tends to convey a business-like
atmosphere while a warm colour appearance indicates a homely feel. As a general rule, the
colour appearance of the light sources used changes from cool to warm as the shop profile
moves from low budget to exclusive. Where daylight is used in the shop it is necessary to
choose a light source colour appearance that blends well with it. For some merchandise, the
colour appearance of the light used is important. Chiller cabinets look fresher and white goods
look crisper and cleaner under a cool light source. Conversely, gold looks more attractive when
illuminated by a warm light source.


The other aspect of light source colour properties that needs attention is colour rendering.
In general, light sources with a CIE general colour rendering index greater than 80 should be
used in retail premises.

This will often be satisfactory but where the merchandise is most likely to be seen under
different lighting, e.g. a coat is most likely to be seen under daylight, it is wise to use lighting
that does not distort the colour of the merchandise relative to how the merchandise will be seen
in use. For some retailers, there can be a temptation to choose a light source that enhances the
appearance of the merchandise. An example is the notorious butcher’s lamp, a lamp that
exaggerates the redness of meat. This is a temptation that should be resisted. In other shops it
will be important to choose a light source with colour rendering properties that give an
appealing appearance to human skin, particularly in areas where an individual’s appearance may
be closely examined, e.g. fitting rooms. While the CIE general colour rendering index is a
useful guide, the final choice of light source is best made by viewing the lit objects of interest.


12.4 Approaches to retail lighting


12.4.1 General lighting


General lighting in shops with a low budget or value for money profile is usually provided from
a regular array of luminaires (Figure 12.1). These luminaires range from bare fluorescent lamp
battens through recessed fluorescent louvres to pendant metal halide globes. The purpose of
such general lighting is to produce a uniform illuminance over the relevant plane without
causing glare.


In shops with quality or exclusive profiles, the architecture is more likely to be a feature of the
store and the general lighting will need to be integrated with it. This may involve the use of
recessed downlights, cove lighting or suspended uplights rather than a regular array (Figure
12.2). Regardless of the lighting approach used, the appearance of the luminaires needs to be
consistent with the style of the shop.


12.4.2 Accent lighting


Accent lighting is designed to provide additional illuminance on some areas so as to emphasise
specific items of merchandise and to provide a meaningful variation in brightness and shadow
throughout the store. If well done, accent lighting can guide shoppers through the shop and
draw their attention to merchandise. The best form of accent lighting depends on the area
to be accented.


For large area wall displays, wall washing luminaires fitted with fluorescent lamps are used
(Figure 12.3). For gondola displays, the lighting can be built into the gondolas (Figure 12.4).
For small area accent lighting, aimable spotlights attached to power track should be used (Figure
12.5). Whatever the form of accent lighting, some flexibility is required. This is because the
nature and aiming of accent lighting will depend on the merchandise to be accented. As the nature and layout of the merchandise changes, the accent lighting will need to change.

Where wall washing luminaires are used, the important characteristic of the luminaires is the
light distribution, the ideal being a uniform illuminance from the top to the bottom of the wall.
A similar consideration applies to accent lighting built into gondolas. The illuminance
distribution from the top to the bottom of the gondola should be as even as possible. Where
spotlights are used, the luminous intensity at the centre of the beam, the shape and dimensions
of the resulting light spot with respect to the size and shape of the area to be lit are important.
Accent lighting in shop windows has competition from daylight reflected from the window
glass and from the windows of nearby shops. Depending on the shielding from daylight and the
lighting of adjacent shops, the general lighting of the window during the day needs to be in the
range 500 to 2000 lx, while accent lighting needs to be in the range 3000 to 10,000 lx. These
illuminances should be reduced after dark.


12.4.3 Display lighting


The function of display lighting in shop windows is to gain the attention of passersby and to
make the merchandise look attractive. Inside the shop, the main purpose of display lighting is to
emphasise the desirable features of specific merchandise. Inside the store, display lighting can
be applied to merchandise open to examination (Figure 12.6) or to merchandise in showcases.

Display lighting is designed to gain attention by using an appropriate combination of brightness,
colour and modelling. Relative brightness can be expressed in terms of the luminance ratios
given in Table 12.2. The higher is the luminance ratio, the more likely the display is to gain
attention. As for colour, strongly coloured light on an object of the same colour will deepen the
colour whilst strongly coloured light on the background and surroundings will change the
atmosphere. The modelling achieved depends on the relative strength of light delivered from
different directions. Modelling is usually achieved by some combination of key-light, fill-light,
back-light and up-light. Table 12.3 describes these techniques.


Table 12.3 Descriptions of the components of display lighting

Figure 12.3 Luminaires providing vertical illuminance.

Figure 12.4 Lighting of a gondola in a shop.

Figure 12.5 A shop lit using spotlight on track

Figure 12.6 Display lighting for mannequins

Figure 12.7 Lighting the racks

Different materials require different display lighting techniques. Table 12.4 lists some of the
more common techniques for specific materials.

Table 12.4 Common display lighting techniques for particular materials