Lumeitalia
A comparison method for luminaires intended for architectural facade and monument lighting: what to look at, what to ignore, how to make data comparable.
Comparing two datasheets is not the same as comparing two installations. In architectural facade and monument lighting projects the right choice only emerges by simulating both solutions in the real geometry and assessing their behaviour over time. Architectural lighting enhances built heritage but is also one of the applications most exposed to criticism for spill light and unnecessary consumption.
The regulatory reference for architectural facade and monument lighting is not a single document but a coordinated set of standards covering performance, safety and environmental impact. In design practice the following documents drive the main choices.
The first step is checking that data come from homogeneous test conditions and that photometric files refer to the configuration actually offered, not to a different variant of the same family. Comparing data gathered under different conditions produces arbitrary conclusions, however precise the numbers look.
Meaningful comparison happens in the project geometry: same grid, same heights, same maintenance factor, same reflectances. Only then can you see which solution meets requirements with lower installed power or fewer light points. Extrapolating from headline figures often leads to conclusions opposite to those of the simulation.
The lighting result should then be paired with an assessment of maintainability, spare-part availability and compatibility with the planned control systems: factors absent from the calculation but decisive over the whole life cycle.
The difficulties that most often emerge in architectural facade and monument lighting projects are not about product selection, but about defining requirements and verifying results.
An orderly method drastically reduces variations during works and disputes at commissioning. Three choices make the difference from the earliest stages.
Non-conformities found at commissioning almost always come from three causes: requirements not declared or declared without a reference standard, calculation run on idealised geometry, and an optimistic maintenance factor. All three can be avoided at zero cost during design.
A architectural facade and monument lighting project holds up over time when requirements are declared, the calculation reproduces real conditions and on-site verification follows an agreed protocol. Component selection matters, but comes later: without measurable requirements even the best product delivers a result that cannot be demonstrated. Centro Studi Lumeitalia makes its technical office available to review requirements and design checks.
Methodological note: This content is written for technical information purposes by Centro Studi Lumeitalia and does not replace the lighting design or a full reading of the standards cited. Applicable performance values are those of the standards in force at design time.
It is the preferable solution where possible, because it drastically reduces upward spill compared with uplighting.
It depends on the applicable regional law: many require switch-off or reduction after a set hour, with justified exceptions for specific assets.
From a written definition of performance requirements and verification conditions: this step drives every later choice and makes the result either disputable or defensible at commissioning.
Photometric files of the proposed luminaires, declaration of conformity, lifetime data declared per IES LM-80 with its conditions, the maintenance schedule and warranty terms.
