Laboratoire de Performance Integree au Design

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Transmittance thresholds of electrochromic glazing to achieve annual low-glare work environments

Marilyne Andersen, Sneha Jain, Jan Wienold

A recent study on the glare protection performance of electrochromic (EC) glazing showed that visible transmittance levels lower than 0.6% are necessary to achieve comfortable situations for sun positions, that were close to the central field of view. However, the question that arises is how often such situations occur throughout the year and how the glare protection performance of EC systems is for typical office situations for different climates and orientations. This study aims to quantify the annual performance for such configurations by applying improved simulation methods to conduct annual glare simulations and comparing them to the EN17037 classifications. The enhancement of the simulation method compared to existing methods was necessary to correctly consider the blurring effect in the lens of the eye – neglecting this would lead to an overestimation of glare. We found that for mid and north European climates the extreme situations do not occur such often, so that the EC- glazing systems being able to switch to transmittance levels of 1% can mitigate glare throughout the year reasonably well for typical office situations and reaches typically the highest glare protection category according to EN17037 for a viewing direction, that is parallel to the facade. For more sunny climates such as Rome, slightly lower transmittance levels (around 0.5%) would be necessary to achieve a similar glare protection level. The study also revealed that tables E.7 and E.8 of EN17037 with pre-calculated 95-percentile Daylight Glare Probability (DGP) values should be re-calculated.

2022

The Canopy Pavilion: A lightweight shading structure using a deployable auxetic linkage membrane

Arthur François Blanc, Etienne Bouleau, Tian Chen, Dieter Dietz, Florin Isvoranu, Mark Pauly

We present the Canopy Pavilion, a lightweight shading structure for a social gathering space. The shading surface is realized as a tensioned auxetic linkage membrane, composed of two double-curved anticlastic layers separated by a compression pole. The membrane is assembled flat on the ground from laser-cut hexagonal aluminium panels, and is subsequently mounted on a circular support frame. Tensioning then deploys the surface to its desired target shape. We apply numerical optimization to form-find the equilibrium shape of the tensioned membrane. The geometry of each individual linkage panel is further adapted to reduce material usage, while maximizing the main function of the structure, to provide shading. Our material system offers a number of distinct advantages. Individual panels can be cut from standard sheet material, all connections between panels are identical, the surfaces can be assembled on the ground and deployed easily to their double-curved shape. The pavilion is a first demonstrator for a novel lightweight construction system at architectural scale that has potential applications in facades, roofs, or support structures.

2022

Validation of spectral simulation tools in the context of ipRGC-influenced light responses of building occupants

Marilyne Andersen, Clotilde Marie A Pierson

With the growing awareness about ipRGC-influenced light (IIL) responses, design applications related to these responses are flourishing. To compare design options and optimize lighting conditions for building occupants, lighting simulations are typically used. However, as our IIL responses depend on the spectral characteristics of light, spectral simulations are required. The goal of this study is to validate two spectral simulation tools, ALFA and Lark, for the study of indoor spaces in relation to occupants' IIL responses. Indicators associated with IIL responses derived from ALFA- and Lark-simulated data are compared against indicators derived from data measured under indoor daylighting and electric lighting conditions. The results show that Lark outperforms ALFA in most cases, with a simulation error in the +/- 20% range for point-in-time indicators. When accounting for time dynamics of light exposure, at least 9% of the daylight exposures simulated for a 6-h period in Lark lead to a significant error.

TAYLOR & FRANCIS LTD2022