Use it all day.
Daylight is available for more than 4,400 hours every year, providing useful illumination even during cloudy weather.
Good architectural decisions benefit from objective evaluation. Standardized methods and design recommendations help make daylight performance measurable and comparable throughout the design process and, where appropriate, after construction.
Scroll to discover how daylight performance can be assessed.
Why assess daylight?
You can't improve what you can't evaluate.
Architectural decisions have lasting consequences for daylight, visual comfort, wellbeing and building energy performance. Standardized assessment methods help architects evaluate these consequences objectively, compare design alternatives and communicate design decisions with confidence.
Daylight provision - why it matters?
Save on lighting.
Natural daylight reduces dependence on electric lighting while improving visual quality throughout the day.
Save on energy.
Daylighting and passive solar strategies can reduce operating costs and environmental impact while making better use of renewable daylight.
See natural colours.
Daylight provides excellent colour rendering, supporting accurate perception of materials, finishes and architectural spaces.
| Recommendation level | ET / ETM (lx) | Reference plane (%): ET / ETM |
|---|---|---|
| Minimum | 300 / 100 | 50 / 95 |
| Medium | 500 / 300 | 50 / 95 |
| High | 750 / 500 | 50 / 95 |
Table 1. Recommendations and performance levels for daylight provision according to EN 17037.
Daylight provision
Learn how architects evaluate whether buildings receive enough useful daylight.
Design considerations
Daylight provision depends on decisions made long before construction begins. Building orientation, surrounding obstructions, window size and position, room proportions, surface reflectance and façade design all influence how daylight enters and spreads throughout interior spaces. These architectural decisions establish the daylight potential of a building and are easiest to improve during the earliest design stages.
Assessment criteria
EN 17037 evaluates daylight provision using standardized daylight metrics that estimate how much useful daylight reaches occupied spaces throughout the year. These objective criteria allow architects to compare design alternatives, verify daylight performance and demonstrate compliance using a common European framework. Assessment may be carried out using daylight factor calculations, climate-based daylight simulations or on-site measurements, depending on the project stage and available information.
Exposure to sunlight - why it matters?
Keep your body clock in sync.
Direct sunlight helps regulate the circadian rhythm and supports a healthy sleep–wake cycle.
Get the sunshine vitamin.
Sunlight enables the production of vitamin D, supporting bone health, immunity and overall wellbeing.
Support health and wellbeing.
Appropriate exposure to sunlight can improve mood, reduce stress and contribute to long-term physical and mental wellbeing.
Benefit from solar heat.
Thoughtful solar design can reduce heating demand during colder months through passive solar gains.
| Recommendation level | Sunlight exposure |
|---|---|
| Minimum | 1.5 h |
| Medium | 3.0 h |
| High | 4.0 h |
Table 2. Recommendations and performance levels for sunlight exposure according to EN 17037.
Exposure to sunlight
Evaluate how much direct sunlight reaches interiors to improve comfort, well-being and the quality of spaces.
Design considerations
Sunlight exposure should be considered alongside daylight, energy performance and visual comfort from the earliest stages of design. Building orientation, surrounding context, façade design, window size, shading devices and the intended use of each space all influence how much direct sunlight reaches the interior throughout the year.
Assessment criteria
Direct sunlight may be evaluated through computer simulations or on-site measurements by assessing the duration of sunlight reaching occupied spaces during defined periods of the year. Standardized performance levels allow architects to compare design alternatives and verify whether spaces receive an appropriate amount of direct sunlight for their intended use.
View out - why it matters?
Be in the picture.
Views provide a visual connection with the outside world, revealing the surrounding environment, weather conditions and time of day.
Relax with the view.
Looking outside offers visual relief, reduces mental fatigue and helps people refocus after prolonged periods indoors.
Home with a view.
The quality of a view influences the attractiveness, value and long-term desirability of homes and workplaces.
Look out, feel safe.
Being able to see the surrounding environment increases awareness, orientation and the sense of personal safety.
| Recommendation level | Horiz. sight angle | Outside dist. | Visible layers |
|---|---|---|---|
| Minimum | ≥ 14° | ≥ 6.00 m | Landscape |
| Medium | ≥ 28° | ≥ 20.00 m | Landscape + 1 |
| High | ≥ 54° | ≥ 50.00 m | All 3 layers |
Table 3. Recommendations and performance levels for view out according to EN 17037.
View out
Evaluate the quality of the view out to assess the visual connection with the surroundings.
Design considerations
The quality of a view depends on much more than the size of a window. Building orientation, viewing direction, surrounding context, distance, landscape, neighbouring buildings and interior layout all influence what occupants experience when looking outside. Good views should be considered as carefully as daylight itself.
Assessment criteria
EN 17037 assesses view out using the horizontal sight angle, the distance to the outside view and the number of visible layers. These criteria help architects compare design alternatives and evaluate the quality of the visual connection between interior spaces and their surroundings. The assessment also considers the clarity and visual quality of the view through the glazing.
Protection from glare - why it matters?
Stay focused, stay sharp.
Controlling glare helps people stay focused by reducing visual distractions and eye fatigue during demanding tasks.
Set up your workspace.
The location of workstations, viewing direction and daylight conditions all influence visual comfort throughout the day.
Shed some light.
Appropriate shading devices help reduce glare while preserving useful daylight and outside views.
Work in harmony.
A visually comfortable environment supports wellbeing, productivity and overall workplace satisfaction.
| Recommendation level | DGP threshold |
|---|---|
| Minimum | 0.45 |
| Medium | 0.40 |
| High | 0.35 |
Table 4. Recommended daylight glare probability (DGP) thresholds according to EN 17037. The applicable threshold should not be exceeded for more than 5% of the reference usage time.
Protection from glare
Evaluate the risk of glare and identify design strategies that improve visual comfort without sacrificing daylight.
Design considerations
Glare should be considered alongside daylight provision, sunlight exposure and the intended use of each space. Window orientation, façade design, shading devices, interior surface reflectance and workstation layout all influence the likelihood of visual discomfort caused by excessive brightness or direct sunlight.
Assessment criteria
Glare protection is assessed using standardized methods that estimate the probability of visual discomfort caused by bright daylight sources within the field of view. These methods allow architects to compare design alternatives, evaluate glare risk and verify that interior spaces provide appropriate visual comfort for their intended activities.