Sports-Lighting Report Glossary for Buyers: Terms That Change Project Decisions

Design Basis: Which Requirement Is Being Tested?

The design basis is the set of requirements and assumptions used to assess the project. It should name the sport, level of activity, relevant standard edition, event conditions and operating modes. “EN compliant” without this context is too broad to establish what a report has demonstrated.

Start by asking whether the report covers training, competition, television production or several separate scenes. Check that the requirements match the procurement brief. A calculation can be technically correct for an activity the venue did not request.

Keep a short list of deviations beside the compliance table. A deviation might be an assumed mounting height or a camera position awaiting approval. Resolve those assumptions before treating the proposal as a final design.

PA, TA and Reference Plane: Where Does the Number Apply?

Principal area and total area identify different reference areas used in sports-lighting assessment. Do not assume that either means the whole fenced enclosure. Obtain the marked drawing and dimensions from the designer. The EN 12193 preview from SIST explains that the principal area can include playing space beyond markings for certain sports.

A reference plane also has height and orientation. A result on a horizontal playing surface is different from a result on a vertical plane. Ask the supplier to label each results page with its area, plane and mode. If those labels are missing, the apparent precision of the lux figure is misleading.

Useful follow-up: “Please show this result on the approved drawing and identify the surface it evaluates.” That request often resolves more than asking for a higher output fixture.

Lux, Lumens and Candela: Three Different Quantities

Lux describes illuminance on a surface. Lumens describe luminous flux, and candela describes luminous intensity in a direction. A high lumen figure does not reveal how much light reaches the field or where it is distributed. The CIE provides the formal definition of illuminance.

When a supplier offers a replacement with fewer lumens, ask for the layout calculation before rejecting it. Conversely, do not accept a higher-lumen alternative without checking the distribution. Light delivered outside the useful area can raise the product figure without solving a weak point on the playing surface.

For quotations, distinguish total luminaire output from an LED component figure. The report and datasheet should identify the tested or declared configuration used in the design. Electrical watts and lumens belong in the evidence package, but neither replaces the calculated result.

Initial, Maintained and Maintenance Factor

Initial illuminance describes a new installation under its stated conditions. Maintained illuminance concerns the level to be preserved as the installation ages and requires maintenance. A new-system measurement should not be presented as a maintained prediction without the relevant assumptions. See the CIE maintained average illuminance definition.

Maintenance factor accounts for relevant losses over time, including dirt and source output depreciation. It is not a warranty period or an arbitrary safety margin. Ask for the cleaning interval, operating environment and supporting assumptions behind it. The CIE maintenance factor entry explains the underlying relationship.

In a simplified illustration, 625 lx initially with an assumed factor of 0.80 yields 500 lx maintained. This is arithmetic, not a recommended factor. If another proposal claims 500 lx but reports only its initial value, the two offers have not demonstrated the same duty. Request a comparison using the agreed maintenance basis.

Average, Minimum and Uniformity

Average illuminance summarizes the evaluated points. Minimum illuminance identifies the lowest sampled value. The usual CIE illuminance uniformity Uo is minimum divided by average. Some specifications and software also report other ratios, so write the formula beside the abbreviation rather than relying on a familiar-looking label. Refer to the CIE uniformity entry.

For illustration, 350 lx minimum and 500 lx average produce 0.70. A second design with the same minimum but a 700 lx average produces 0.50. More average light has not improved this ratio. This does not make the first design automatically preferable; both must satisfy all applicable requirements.

Ask for the coordinates of the minimum and the underlying grid. A buyer needs to know whether the weakest location is a repeatable result at an important edge or a value produced by a different assessment surface.

Horizontal, Vertical and Luminance

Horizontal illuminance is commonly used to evaluate a horizontal playing surface. Vertical illuminance evaluates a vertical plane and depends on its direction. Camera-facing requirements therefore need defined camera or reference directions. One horizontal average cannot demonstrate every required vertical result.

Luminance is a different quantity, expressed in candela per square metre and associated with light from a surface in a specified viewing direction. It is not another name for lux. The CIE luminance definition provides the formal distinction.

When a report switches between these quantities, check both units and geometry. Ask which visual task each page is intended to address. A glossy rendering may look convincing while concealing that the requested directional assessment has not been supplied.

GR, UGR and Obtrusive Light

Glare ratings are assessment results tied to a method and viewing conditions. CIE 112 describes an evaluation system for outdoor sports and area lighting; its scope is different from assessing spill outside the illuminated area. A product advertised with a low glare number has not established that number for every installation. See CIE 112.

GR and UGR should not be substituted for one another merely because both concern glare. Ask which method the applicable requirement uses and request the observer positions, viewing directions and assumptions. Pole locations and aiming can change the result even when the fixture remains the same.

Obtrusive-light review concerns effects beyond the intended task area. Request the relevant boundary or receptor assessments separately. A satisfactory player-facing glare result does not demonstrate acceptable conditions at a neighboring window.

CCT, CRI and Temporal Light Behavior

Correlated color temperature describes color appearance; color rendering describes how colors are rendered under the source. These are separate from illuminance and optical distribution. A higher CCT is not proof of better field visibility, and a higher CRI is not evidence that the layout meets its lux target.

Specify color requirements for the actual use and destination market, then request confirmation for the ordered configuration. A product family may offer several versions. The data used for the calculation and the version shipped should remain traceable.

“Flicker-free” is an incomplete purchasing statement unless the test method and operating conditions are stated. For a camera-sensitive project, identify the production requirements and request relevant test evidence at the planned output settings. Performance at full output does not establish every dimmed condition or every camera mode.

IES, LDT, Optical Code and Aiming

IES and LDT files carry photometric data used by lighting software. A file extension does not certify that the data describe the offered product. Check the model, optical version, output basis and any scaling applied in the calculation. Ask for the supporting photometric report when the file identity is unclear.

Beam-angle labels are useful for sorting options but do not describe the complete distribution. Two optics described as narrow can put very different amounts of light into the surrounding angles. The calculation must use the actual distribution rather than a generic cone drawn on a site plan.

An aiming schedule connects that distribution to the installation. It should identify fixture positions and directions in a form the installer can reproduce. A change in bracket orientation or mounting position may invalidate the intended aiming, even if the luminaire model number is unchanged.

Operating Mode, Input Power and Failure Case

A lighting scene identifies which fixtures operate and at what settings. A training mode, competition mode and a specified failure arrangement are separate assessments. Reducing the number of active fixtures can change distribution differently from reducing every fixture’s output.

Input power is electrical consumption for the stated configuration and operating condition. It should include the relevant driver or system loads consistently. A dimming percentage is not automatically the same percentage of full-load electrical watts. Use confirmed input values when estimating operating cost.

Backup capability needs its own documentation. A normal sports-lighting report cannot demonstrate escape lighting, transfer behavior or operating duration. Ask which failure mode was modeled and which separate electrical or safety evidence closes the remaining requirements.

Calculated, Measured and Accepted

A calculated result is a prediction from a model. A measured result records an installation under stated conditions. Acceptance is the agreed decision process for evaluating the supplied work. These three terms should not be merged into a single word such as “verified” without explaining what was done.

For site measurements, require the grid, plane, instrument information, operating state and relevant environmental observations. Compare the installed arrangement with the model before interpreting differences. A moved pole, changed output setting or temporary obstruction can matter more than another decimal place in the report.

When a supplier proposes an alternative ZC Lighting configuration, request the corresponding data and revised calculation before approval. Keep the accepted optical file, aiming schedule and equipment record together. That package is also what the maintenance team needs when a replacement is purchased later.

Five Questions That Turn Terminology Into a Decision

Read the small print below a results table as carefully as its green cells. A report may use an output multiplier, omit an unconfirmed area or exclude a mode from the assessment. Ask the designer to explain the purpose of each adjustment and whether it represents the equipment being purchased. A transparent assumption is useful; an adjustment that cannot be traced to the brief needs resolution.

Also distinguish a design recommendation from a contractual requirement. Software can flag a selected target, but selecting that target is a project decision. The buyer still needs to know who authorized it and which source or approved brief supports it.

First, what exact requirement is this result being compared with? Second, where is the evaluated surface and how was it sampled? Third, is the output initial or maintained, and under which operating mode? Fourth, which equipment configuration and photometric data produced the result? Fifth, how will the installed work be checked against it?

Send those questions with the quotation request. They help the supplier provide a comparable offer and reveal unresolved assumptions before procurement. A useful report makes the answers easy to locate; the buyer should not have to infer them from color maps or marketing specifications.

The purpose of this glossary is to make a purchasing decision traceable. Understanding the terms helps, but the final approval should rest on the matching drawings, data and acceptance records.