Published at the end of 2018, the new European Standard EN 17037 deals with daylight in buildings. It is the first Europe-wide standard to deal exclusively with the design for, and provision of, daylight. EN 17037 replaces a patchwork of standards across different European countries or provides one where no existing standard is present.
Daylight is important for the health and wellbeing of building users, for providing sufficient illumination to carry out tasks, and for giving a connection with the outdoors. Providing appropriate levels of daylight also helps in saving energy, by not having to rely on artificial lighting as often. All of these factors have driven EN 17037’s publication.
Are there existing daylight design standards?
BS 8206-2:2008 is the code of practice for daylighting. As it is a British Standard, it applies to the UK only and gives recommendations for daylight design in buildings, including how electric lighting can be designed when used in conjunction with daylight.
EN 17037 deals exclusively with daylight and includes other methods of calculation for design parameters that do not feature in BS 8206-2.
Some existing European Standards include daylight as a factor - for example, EN 12464-1 and EN 15193. However, both of these also look at it in the context of electric lighting provision, and so EN 17037 is truly unique in focusing on the quantity and quality of daylight for building users.
What areas of daylighting design are covered by EN 17037?
The new European Standard for daylight design covers four different areas:
- daylight provision
- assessment of the view out of windows
- access to sunlight
- prevention of glare
Some designers may already have familiarity with designing to provide daylight, but the other three aspects of design significantly extend the scope of the standard.
How is the provision of daylighting design measured?
To provide flexibility for architects and designers, while also making the standard useable and understandable, EN 17037 sets a minimum level of performance that must be achieved for each of the four areas of daylighting design.
As well as the minimum recommendation, it also gives two further performance levels: medium and high. Users of the standard are free to select the performance level that best relates to the building design and proposed building use.
A simplified and detailed method is available with which to assess each design area. The standard harmonizes the evaluation of daylighting but takes into account national and local conditions so that solutions are appropriate and specific to each project.
Designing for daylight and building occupant comfort
Daylight provision, or illuminance levels, allow users to carry out tasks and play a part in determining the likelihood of artificial lighting being switched on. Assessment can be via either climate-based modeling or daylight factor calculations.
Building users should have a large, clear view of the outside. EN 17037 considers the width and outside distance of the view, as well as landscape ‘layers’ (sky, landscape, and ground). The view should be perceived to be clear, undistorted and neutrally colored. Width of view can be established via a detailed or simplified approach. Outside distance and number of layers are each measured by a single approach.
Calculating access - or exposure - to sunlight is a comfort and health factor for people in dwellings, nurseries, and hospital wards. Daily sunlight exposure can be established through detailed calculation or table values.
As its name suggests, prevention of glare is concerned with removing the probability of glare for building users, especially those who do not choose where they sit. It uses a detailed calculation of daylight glare probability (DGP) or a standard table of values for sun-screening materials.
What building types does EN 17037 apply to?
The new European standard for daylight design in buildings, EN 17037, has been written so that it can be applied to any building. The areas of design covered by the standard, and the flexibility for designers to choose what performance level is achieved, means internal spaces can be designed to suit intended activities.
Does EN 17037 require specific levels of illuminance?
When it comes to daylight provision, the standard only gives levels of illuminance in terms of the minimum, medium and high-performance levels that are a feature of the document. It does not specify levels for particular tasks or building uses.
The minimum level of 300 lux is based on a number of studies, having been described as suitable illumination for prolonged office work, and the level at which the probability of switching on electric lighting is low. Design levels for artificial lighting also use a 300 lux threshold.
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