# A Review of Light Shelf Designs for Daylit Environments
## 4 Conclusions
The use of a light shelf can increase the signal of the sensor due to the reflected illuminance making it difficult to accurately track the illuminance changes on the working plane. Therefore, more studies are needed on real spaces equipped with light shelf and daylight dimming systems. A decision support system (DSS) would be most welcomed by the design teams. This DSS should be based on a benchmarking process which involves estimating the performance of a specific light shelf design against a reference case. This case involvesthe use of a test room with specific dimensions. Benchmarking a design can provide insight into how well this is performing, allowing the design team to discover what characteristics need improvements. Last but not least, all the aforementioned issues should be accompanied by a life cycle assessment to identify the types of light shelves that are environment friendly. The conclusions of this review help to identify the strengths, weaknesses, opportunities and threats of the light shelves as a daylighting/shading system. These are presented in Table 1 as a result coming from the literature analysis. Figure 16 presents the annual number of papers reviewed from 1983 till today. It seems that in the last two years there has been a substantial increase in this number. We believe that the reason for this increase is the effort to achieve cost efficient solutions in order to exploit daylight, and, of course, the improvements in the daylight simulation software. \begin{table}
\begin{tabular}{l l l} \hline \hline \multicolumn{1}{c}{**Strengths**} & \multicolumn{2}{c}{**Weaknesses**} \\ \hline \(\bullet\) & Indoor lighting environment improvement. & \(\bullet\) & Justification of energy savings. Total energy savings are questionable since any increase in solar gains \\ \(\bullet\) & Productivity, well-being and mood improvement. & \(\bullet\) & might offset lighting energy savings. \\ \(\bullet\) & Illuminance uniformity improvement. & \(\bullet\) & Reflected illuminance can deteriorate the performance of a daylight-linked lighting control system. \\ \(\bullet\) & Lighting energy savings increase. & \(\bullet\) & Glare problems. \\ \(\bullet\) & Ease of installation. & \(\bullet\) & Maintenance, especially for dynamic systems. \\ \(\bullet\) & Well-accepted by architectural community. & \(\bullet\) & Daylight analysis software limitations. \\ \hline \multicolumn{3}{c}{**Opportunities**} & \multicolumn{2}{c}{**Threats**} \\ \hline \(\bullet\) & Development of new coatings/materials in an effort to & \(\bullet\) & Manufacturing of curved highly reflecting surfaces might be difficult. Any intolerance might adversely affect user acceptance. \\ \(\bullet\) & Davidish analysis software improvement. & \(\bullet\) & There is a lack of the expertise needed for advanced \\ \(\bullet\) & Manufacturing process upgrade for producing curved & \(\bullet\) & affect user acceptance. \\ \(\bullet\) & Light shelves. & \(\bullet\) & There is a lack of the expertise needed for advanced \\ \(\bullet\) & Development of control algorithms for sun tracking & \(\bullet\) & light shelf design since current design methodologies are quite complicated for the design teams. \\ \(\bullet\) & Cost reduction. & \(\bullet\) & Cost effectiveness. \\ \(\bullet\) & Benchmark development. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Synoptic presentation of the strengths, weaknesses, opportunities and threats of the light shelves as a daylighting/shading system. Figure 16: Annual number of papers dealing with the impact of light shelves on the illuminance in buildings. The main results of this work point out that there is research that needs to be realized in order to improve the performance of light shelves. It seems that there are several opportunities in relation to new materials, new geometries and dynamic operation of the light shelves, defining the future research focus. This study was funded by the \"Research projects for excellence IKY/SIEMENS\".