Principal Area vs Total Area: How the Reference Area Changes Sports-Lighting Results

What PA and TA Actually Identify

EN 12193 uses principal area, or PA, for the playing area needed by the sport. It often follows the marked field, but for some sports it includes additional playing space beyond the markings. Total area, or TA, generally combines the principal area with an additional safety area. The relevant sport and competition level determine the geometry to investigate. These definitions are explained in the SIST preview of EN 12193:2018.

The practical consequence is simple: drawing a rectangle around visible lines does not establish the PA. Likewise, calling everything inside a fence the TA does not establish the correct total area. Check the applicable sport requirements, facility drawing and adopted standard together. Record the source and edition used to settle the boundaries.

This guide does not assign a universal extra strip or a universal TA lighting percentage. Those details belong to the applicable requirements. Its purpose is to show how an agreed boundary changes the meaning of a result and how to keep that boundary consistent through procurement.

Put the Reference Areas on the Approval Drawing

Use separate outlines for the field markings, PA, TA where applicable, spectator areas and access routes. Include dimensions, coordinates and the evaluation height. For a rectangular area, a length and width without an origin are insufficient: the same rectangle can be shifted relative to the poles and sample different parts of the beam pattern.

A tennis enclosure illustrates the problem. The marked court, the space needed around it for play and the fence line are visibly different boundaries. The designer must establish which requirements apply to which surface. Neither the sales drawing nor the visual appearance of the enclosure should silently make that decision.

Ask the venue representative and lighting designer to approve this drawing before competing proposals are compared. The electrical contractor should receive the same revision. Otherwise, a later conversation about a dark edge may become a dispute over whether that edge was included in the order.

How a Larger Area Changes the Numbers

Consider an illustrative calculation using equally weighted sampling points. Twenty points inside the agreed PA have a combined illuminance of 10,000 lx, an average of 500 lx and a minimum of 350 lx. The minimum-to-average ratio is 0.70. These numbers are invented for the example; they are not a requirement or a measured ZC project.

Now include ten additional points in a surrounding strip, using a compatible grid for this illustration. Their combined value is 2,000 lx and their minimum is 100 lx. Across all thirty points, the average becomes 400 lx and the minimum-to-average ratio becomes 0.25. The original PA result has not changed. The wider assessment has revealed a different distribution.

Neither row proves compliance until it is matched to the correct criterion. The example also assumes compatible, equally weighted points. Do not combine separate grids by averaging their reported averages unless their weighting supports that operation. A prescribed calculation method may require different treatment. Keep the PA and TA reports separately identifiable rather than hiding both inside one favorable headline.

The Grid Is Part of the Result

Moving, removing or adding points changes what is sampled. A coarse grid can miss a narrow weak zone between beams. A shifted grid can place points closer to bright regions. This is why a report should state the grid coordinates, spacing, number of points and evaluation plane, not just show a colored rectangle.

Require the numerical point table or an export that can be checked. If two bidders use different grids, ask them to rerun the agreed one before comparing minimum values. More points are not automatically the correct answer either: the method should follow the applicable requirement and remain reproducible.

Do not delete a low point because a goal, bench or temporary object makes it inconvenient. Establish how permanent obstructions and excluded surfaces are to be treated, document the reasoning and obtain approval. An exclusion should describe the actual facility and accepted assessment method, rather than improve a ratio after the calculation is complete.

Read the Ratio With Its Surface Attached

The CIE definition of illuminance uniformity uses minimum divided by average illuminance on a surface. A report may also show other ratios under different labels. Write out the formula when comparing results; a value of 0.70 means little without its numerator, denominator and reference area. See the CIE uniformity definition.

A small bright area can increase the average while leaving the minimum unchanged, reducing this ratio. Conversely, changing the area can remove the weakest location and make the ratio look better. Ask where the minimum occurs. Its position may matter more to the next design revision than the decimal value alone.

When a TA result is weak, inspect the surrounding strip and the PA separately. The response might involve a different distribution or aiming arrangement rather than increasing every luminaire’s output. Any revision should then be checked for player glare, boundary effects and the other required surfaces.

Area and Measurement Plane Must Travel Together

A horizontal surface at playing level answers a different question from a vertical plane facing a camera. Giving both the same outline does not make their illuminance values interchangeable. Name the plane, height and orientation next to every result, including any directional vertical assessments requested for the event.

For indoor facilities, confirm that the model includes relevant geometry and surface assumptions. For outdoor facilities, record pole locations, mounting heights, aiming and any objects that materially affect the modeled distribution. Keep these inputs unchanged when evaluating whether an area revision alone explains a difference between two reports.

A useful comparison sheet has one row per surface and operating mode. PA horizontal, TA horizontal and each required vertical direction should remain distinct. This prevents a report summary from substituting the best result for the result actually requested.

Multi-Sport Facilities Need More Than One Rectangle

A hall marked for several sports or a field divided into training areas creates several possible operating arrangements. Identify which sport, orientation and lighting scene is being assessed. A whole-field result does not establish the performance of a cross-field training layout when only part of the installation operates.

Ask the operator which arrangements will actually be used. Preparing every imaginable layout wastes design time, but omitting a regular booking format leaves an approval gap. Name each agreed arrangement in the quotation and keep a separate plan showing its relevant reference areas.

Where adjacent activities operate simultaneously, review their interaction. A luminaire serving one area may enter the sightline of a player in another. The area definition is the starting point for that review, not proof that all visual conditions have been addressed.

Commission the Area That Was Approved

Before the site visit, issue a measurement plan derived from the approved calculation. Include the point identifiers, coordinates, instrument orientation, operating scene and method for recording site conditions. Confirm that the venue will be available and that temporary installations will not obstruct the agreed assessment.

At the venue, establish the drawing origin from identifiable physical references. Check the real pole and luminaire arrangement against the model. If a pole moved during construction, note the deviation before interpreting the readings. Repeating the old calculation without the actual geometry cannot explain the installed result.

Separate initial commissioning measurements from maintained design targets. New equipment, clean optics and the current output setting influence a site reading. Agree how the acceptance procedure relates those readings to the design assumptions. Avoid applying an unexplained adjustment merely to make the measurements resemble the report.

If a low result appears at the edge, repeat the reading using the agreed procedure, verify the coordinate and investigate aiming or obstruction. Record a correction and retest the affected surfaces. Removing the point or renaming the area is not a corrective action.

Make the Reference-Area Schedule a Contract Attachment

A compact schedule can prevent a long dispute. For each sport and mode, list the drawing revision, PA and TA boundaries, evaluation plane, grid, required metrics and acceptance method. Include the party responsible for resolving a mismatch between the venue drawing and the sport requirements.

Ask ZC Lighting for a proposal against that schedule, with the exact luminaire configuration, optical file and aiming plan identified. Product wattage or a family name alone cannot establish area performance. Any offered configuration must be evaluated in the agreed geometry before it becomes the approved supply.

When the client changes a field dimension, fence position or use pattern, ask whether the reference-area schedule also changes. Record the design impact before accepting a price or delivery consequence. The same control should apply if a contractor substitutes a luminaire, optic or mounting bracket.

The Final Check Before Approval

Keep the full numeric export as well as the PDF summary. In a later review, a screenshot may show the contour colors but omit the point values, scale or active scene. Name the calculation files so that the drawing revision and assessed arrangement can be recovered without relying on someone’s email history. Archive superseded versions rather than allowing them to circulate as equally valid options.

For a phased installation, identify the temporary operating area separately from the completed venue. The first phase might use the final poles but only some of the planned luminaires. Ask for an assessment of the arrangement that will actually open to users. Future equipment shown on a masterplan cannot support an acceptance conclusion about the lighting available today.

Open the drawing and the results page side by side. Can another engineer identify every assessed surface without asking the original designer? Can the commissioning team reproduce the grid? Can the buyer connect the quoted fixture to the photometric file used in the report? If one answer is missing, the package is not yet clear enough to approve.

PA and TA become useful when they keep design, supply and acceptance aligned. Their purpose is not to create another acronym in the tender. They make it possible to say precisely where the promised lighting performance applies.