Daylight planning and planning responsibility

Lighting design

Daylight planning between delegation or leadership?

Daylight in healthcare buildings
Daylight in Museums

DIN EN 17037 – Between standards, perception and planning responsibility. 
In current planning practice, daylight in interiors is increasingly no longer understood as an original design task, but primarily treated as a parameter that needs to be demonstrably proven according to norms. The assessment is often carried out within the scope of technical specialist planning – with a focus on simulations, key figures, and formal compliance with standards.

Berlin Museum Hamburger Bahnhof
Berlin Museum Hamburger Bahnhof

This development leads to daylight being captured computationally but decoupled in its design. Issues of spatial perception, non-visual effects, visual relationships, and atmospheric quality take a backseat to mere record-keeping.

A technical gap is emerging here. Daylight is not purely a technical performance indicator, but an architecturally effective medium, the quality of which cannot be solely depicted through norm levels, illuminance values, or simulation models. Its effect arises from the interplay of space, use, visual reference, and temporal change – and must therefore be considered early and integrally.

1. Daylight provision – from minimum brightness to target value

A key element of DIN EN 17037 is the assessment of daylight provision.
Unlike many previous standards, which were predominantly based on minimum values, DIN EN 17037 takes a more qualitative approach to assessment

The assessment is based on whether specific illuminance levels are achieved solely through daylight over a defined period on specified portions of the reference spatial area. The key consideration is not a pinpointed maximum, but rather an annual perspective.

The standard distinguishes between several recommendation levels (e.g., low, medium, high), which allow for a qualitative classification. However, it does not definitively specify which level is appropriate for which use. This means that deriving the target quality remains a planning task that must take into account usage, context, and architectural framework conditions.

Proof procedure
Evidence of daylight provision can be demonstrated in two ways:

  • about simplified key figures (e.g. daylight factor)
    or via dynamic illuminance simulations throughout the year

Both methods have different assumptions and do not necessarily lead to identical results. Dynamic simulations, in particular, require profound knowledge, as boundary conditions such as sky states, shading, or sun protection systems have a significant influence on the outcome.

2. Prospect – qualitative extension with methodological limitations

Another key element of DIN EN 17037 is the assessment of the view.
This is not carried out across the entire space as a whole, but rather for the areas where users actually spend time.
The following will be assessed, among other things:

  • the width of the view (horizontal field of view)
  • the external visual range (distance to opposite building structures)
  • the number of visible layers (ground, landscape, sky)

The assessment is based on findings from preference studies and describes which constellations are perceived as high quality. At the same time, it must be noted that the standard does not make any direct statements about the psychological effects of views in terms of occupational health or building code requirements.

In addition, neither the exact „area of use“ nor the operating status of solar or glare protection systems are clearly defined. Therefore, the application of the criteria requires interpretation and transparency to achieve consistent results.

3. Duration of Sunshine – Direct Sunlight as a Special Case

The DIN EN 17037 standard also takes into account the potential duration of exposure to direct sunlight. Direct sunlight produces illuminance levels that are far higher than typical indoor levels and may be significant from a biological perspective.

The standard specifies minimum times for this under clear geometric boundary conditions. However, these differ methodologically from previous regulations and are not directly comparable. Factors such as window reveals, minimum solar altitude angles, and verification locations significantly influence the calculable solar exposure duration.
Sun exposure is therefore understood as a qualitative additional aspect – not as the sole criterion for daylight quality.

4. Glare protection – Introduction of dynamic assessment methods

A key improvement in DIN EN 17037 lies in the systematic assessment of glare caused by daylight. The Daylight Glare Probability (DGP) is used for this purpose.
The assessment is usually carried out via an annual simulation, which determines how often defined limit values are exceeded. This procedure is particularly relevant for activities near windows (e.g. reading, writing, screen work).

Before the introduction of the standard, DGP was hardly widespread in European planning practice. Consequently, the demands on expertise, software, and interpretation of results are high. The standard allows for simplified verification procedures for selected standard situations, but does not replace professional assessment.

5. Implications of DIN EN 17037 – greater precision, greater integration

Overall, the DIN EN 17037 standard represents a significant shift towards a more scientific approach to daylight assessment. Structural analyses are increasingly being supplemented or replaced by dynamic simulations. As a result, daylight, façades, sun protection and artificial lighting are becoming more closely interlinked.
This development opens up new possibilities – but also leads to conflicting objectives:

  • Larger window areas vs. summer heat protection
  • High daylight levels vs. energy efficiency
  • Normative claim vs. urban context

The standard itself does not resolve these conflicts. It makes them visible.

6. Daylight planning as an integral part of lighting design

It is precisely against this backdrop that it is crucial not to view daylight in isolation. DAY & LIGHT positions daylight planning as an integral part of early, comprehensive lighting design, which begins in collaboration with architects during the first service phase of HOAI.
In this phase, the following will occur:

  • Spatial depth and proportions
  • Opening logic
  • Sightlines
  • Interactions with interior lighting

fundamentally defined. On this basis, technical specialist planners can be specifically involved to carry out simulations, verifications, and optimisations with sound expertise.

DIN EN 17037 – Role and responsibilities

What the standard achieves

  • Qualitative assessment of daylight supply, view, solar gain and glare
  • Introduction to Dynamic Detection Methods
  • Europe-wide comparability

Note: The application of DIN EN 17037 requires specialist knowledge and an understanding of the context. Results must always be assessed in the context of usage, architecture and technology.

DIN EN 17037 – Role and responsibilities

What they don't replace

  • architectural decisions
  • Prioritisation in the case of conflicting objectives
  • Integrated lighting design
  • Professional interpretation of the results

 

Classification and further development

Standard DIN EN 17037 provides a comprehensive set of tools for assessing daylight in interior spaces. However, its benefits can only be realised if it is applied in an integrated manner and incorporated into the design process.
Paul Ott ZWT scaled JPG