Thijs Hamilton - Daylight control modelling with a multi-screen shading device - Stichting Dutch Daylight

Thijs Hamilton – Daylight control modelling with a multi-screen shading device

Nomination Dutch Daylight Student Award 2024
Project type: Research

Daylight control modelling with a multi-screen shading device
Case study on Museum Boijmans Van Beuningen in Rotterdam

Thijs worked on developing a shading control strategy tailored for museums with sensitive artwork. His approach involved simulating various shading parameters and assessing the resulting light exposure. The outcome of his research is a more efficient decision-making process, helping curators and designers select the optimal shading combination to protect valuable artwork.

Topic: shading control strategy for museum with sensitive artwork
Method: simulation of shading parameters and final light exposure
Impact: Streamlined the decision process to pick the best shading combination

For a museum, it is important to be able to regulate the amount of daylight. Daylight influences the experience of the visitors, but it can also have a harmful effect on the displayed artwork. Within this thesis, the framework of an approach is outlined. The museum Boijmans van Beuningen in Rotterdam is currently closed for restoration. The oldest part of this museum was built around 1930. The architect Van der Steur made an extensive study of lighting in museum rooms. For the final design of the building, this resulted in a pitched roof with glass and a layer of horizontal glass panes (legramen) that form the ceiling of the exhibition rooms. Below the glass panes timber blades (schoepen) are placed under an angle to disperse the light around the room as seen in Figure 1. For the restoration, the museum board wants to preserve the original vision on daylight of Van der Steur and is now considering the options for sun shading above the ceiling. This addition will allow the museum to better control the light levels in the museum and to protect the valuable artwork. For this situation, the research question was formulated: How to design a method to assess the daylight exposure in museum BVB, to be used for a combined lighting design (daylight and artificial), focussing on optimal visibility and art protection, to assess a multi-screen shading device and its effects on the illuminance?

This report (Hamilton, 2024) describes a method to assess the daylight exposure in the museum Boijmans van Beuningen, without the need for extensive real-world measurements. It can be used for a combined lighting design (daylight and artificial), focusing on optimal visibility and art protection. The purpose of the method is to compare different sun shading solutions and their effects on the illuminance in an exhibition room. With this approach, a toolbox is made that can also be used on other museums with top light rooms. For the restoration, the museum board has chosen an illuminance level of 250 lx with an art – wall ratio of 2:1. This means that the illuminance on the wall is restricted to 125 lx (CIE 157, 2014) (NPR-CEN/TS 16163, 2014).

The method starts with a 3D model of one of the museum rooms, based on the design model supplied by the architect. As the museum is currently being restored, several alterations had to be made to accommodate the temporary renovation state. For the validation of the model, HDR images were made on-site. This method is described by (Pierson, Cauwerts, Bodart, & Wienold, 2021). The validated model can be used for the calculation of the sun shading system. For the total process several steps were needed to combine different models, as illustrated in Figure 2. In Figure 3 a cross-section of the model is shown, with the different elements of the sun shading system.

These results were compared with the calculation made with the 3D model. By iteratively adapting the characteristics of the floor, the schoepen and the legramen the best possible fit was made. The resulting false colour images are given in Figure 4 to Figure 9. The scatterplot in Figure 10 shows a strong positive association between the HDR and the simulated results. Using the Morris method a sensitivity analysis was done to determine which parameter has the most influence on the system (Morris, 1991). The wall is the most dominant factor (Figure 11). With the validated model an hourly daylight simulation was done using the EPW climate-based weather data. The resulting illuminance exceeded the desired level at several points in time in the museum. For the calculation of the effects of the sun shading, three different types of sunscreens were chosen. These were schematised as a continuous horizontal layer on top of the legramen.

For 3 sensor points around the room (Figure 12) the behaviour of the sun shading was calculated on three specific days (the 21st of June (summer solstice), the 21st of December (winter solstice) and the 21st of September (equinox, halfway between solstices). Figure 13 to Figure 15 show the maximum values for each hour. A daylight factor of 2% was found between the illuminance on the wall and the outside
illuminance, Figure 16. With this relation and the EPW weather data, it is possible to predict the desired sun shading states for an entire year, see Figure 17. This procedure can be used to develop a control mechanism for the opening and closing of the sun shading based on local measurements. When the sun shading state changes, the illuminance can fall below the desired level of 125 lx. In that case, additional artificial lighting is needed.