Solving Glare Problems in Architecture Through Integration of Hdri Image Techniques And Modeling with Diva

This paper describes a replicable process of design solutions to problems of excessive direct glare in buildings. First, glare is evaluated using HDR image technique. Second, a Radiance model of the building is calibrated using the HDR images. Finally, proposed shading strategies are evaluated using the calibrated model and DIVA annual simulation of glare. A case study using a recently completed building with severe glare problems provides a demonstration of the method. Three potential shading strategies are evaluated: brise soleil, venetian blind and mechoshade. The ability of each to reduce glare is discussed and a solution is proposed. INTRODUCTION AND OBJECTIVES A well-designed daylit space should satisfy both quantitative and qualitative respects. The former one refers to a space with sufficient illuminance ratios on working planes in even distribution; the latter one is related to a comfortably visual environment for occupants. In order to reach this goal, shading device is usually implemented to block direct sunlight and reflect parts of it to the rear space. With the absence of shading device, a space may have a risk of severe glare. The popularity of glass curtain wall in modern buildings has led to many situations of severe glare. In this paper, the more serious glare issues come from a huge curtain wall in winter with low sun angles. Under this situation, the authors combine the method of physically analysing glare by using High Dynamic Range (HDR) images with the available simulation tools of estimating glare. The application of these tools allow analysis of solar control strategies to effectively reduce the glare in the space. A recently completed hospital located in Milwaukee (43.1N, -87.8W), USA, has severe glare in its twostory entry lobby and patient commons. The facility is located on a bluff overlooking Lake Michigan, and the lobby and common space is enclosed by a twostory curtain wall. The lobby is a congregation spot to welcome patients, to ask information, and to direct patients to the appropriate waiting area in the commons, the plan is illustrated in Figure 1. The lobby is an 18.3m by 14.8m rectangle facing southeast. The waiting area is 104.3m along eastwest direction by 9.4m along north-south direction with glazing facing south and southwest. The ceiling is 11.6m high with two four-floor height sections reaching 21.3m. With the tall curtain wall facing southeast, south and southwest, the common presents the occupants with direct sunlight and serious glare problems, especially in winter with low sun angles. Movable partitions have been added and moved around by staff throughout an entire day to temporarily block direct sunlight (Figure 2 a and b). A shading strategy is desired to reduce glare and provide both staff and patients a visually comfortable environment. There are a number of studies illustrating the effectiveness of shading strategies with regard to illumination and luminance levels and energy impacts. There are few studies concerning daylighting performance in terms of combination of static and dynamic glare. Since this paper is primarily a response to the reduction of glare, other criteria concerning thermal environment or energy consumption is beyond the scope of this paper.