Daylight, Energy and Sustainable Buildings

In an age where quantification reigns supreme, lighting design finds itself at a crossroads. From lux levels to lumens-per-watt, metrics have undeniably driven remarkable advances in lighting performance, efficiency, and standardization. But as our environments become increasingly measured, we must ask: are we optimizing the right things?

This talk explores the double-edged nature of metrics in lighting — powerful tools for progress, yet potentially reductive when used without context or vision. Using comparative urban case studies such, we reflect on how different metrics—car counts vs. human activity—led to vastly different mobility strategies and urban atmospheres. Similarly, the evolution of lighting technologies, from incandescent to LED, has improved energy efficiency exponentially, but often at the expense of visual comfort.

The paper also delves into emerging challenges brought about by innovations such as Human Centric Lighting. While tunable white and spectral precision have the potential to enhance circadian health, they often prioritize human benefits in isolation, ignoring broader ecological consequences. This calls for a paradigm shift from human-centric to eco-centric lighting — one that values biodiversity, light pollution reduction, and nighttime preservation.

Technological precision has raised expectations. Metrics like lx/W offer more targeted evaluations of lighting effectiveness in application, while new indices could quantify color shifts, and even “bad lumens” — those contributing to glare or spill light. However, even these advanced metrics cannot replace the necessity of holistic, context-sensitive design thinking. A light that performs perfectly on paper may still fail in practice if it undermines user comfort, spatial identity, or long-term adaptability.

This presentation advocates for a broader, systemic approach to lighting progress. It highlights the role of adaptive infrastructure — such as flexible systems and upgradeable luminaire software — as pathways to sustainable, future-proof design. It underscores the need for dynamic, evolving eco-standards that push beyond static efficiency targets, and for lifecycle-based assessments that inform environmentally responsible manufacturing and procurement.

Ultimately, we must reframe the purpose of measurement. Metrics should not be the end, but a means to enhance. As AI and data-driven design become more prominent, the risk grows that we will chase averages rather than embrace complexity. The future of lighting depends not just on what we can measure, but on what we choose to value.

By bridging performance with purpose, and metrics with meaning, lighting design can lead the way toward environments that are not only efficient, but enriching — for people, places, and the planet.

Residential spaces have increasingly evolved into hybrid environments that support living, studying, and work-related activities. Daylight, due to its critical visual and non-visual effects on occupants, is the most effective source for achieving optimal performance in various visual tasks. As residential spaces are now more frequently used as daytime working environments, the rise in lighting energy consumption emphasizes the need to effectively utilize daylight through daylighting systems. However, existing studies have not evaluated how daylighting system designs—particularly when combined with manually operated shading devices—affect lighting energy consumption while ensuring the required visual comfort conditions for multiple visual activities in hybrid residential spaces. Therefore, this study aims to assess the impact of different daylighting system solutions on lighting energy consumption while maintaining visual comfort for diverse visual tasks.

For a residential room with single-sided daylight opening, multiple design parameters—including room geometry, window size, and shading device configurations—are parametically examined to identify daylighting solutions that satisfy visual comfort requirements and minimize lighting energy demand. Grasshopper for Rhino is used to generate a parametric residential model incorporating design parameters that influence daylight performance across different design stages. The visual comfort assessment follows EN 17037 criteria, covering daylight provision, glare, and view out. Each visual comfort metric is calculated separately for each visual task area within residential spaces accommodating both living and working activities. In the final stage, the overall visual comfort performance of the hybrid-use residential space is determined using a weighted matrix approach, whereby the visual comfort conditions achieved in each task area are evaluated based on function-oriented, area-based weighting coefficients. Lighting energy consumption is evaluated using daylight autonomy which is the primary indicator of daylight-responsive lighting energy demand. Simulations are performed in ClimateStudio under two shading scenarios: with and without manually controlled interior shading devices that reflect occupant-driven behavior. The comparative analysis reveals daylighting design strategies that address the visual comfort needs of multiple activities in hybrid-use residential spaces while ensuring energy-efficient lighting performance, thereby supporting healthy, comfortable, and energy-efficient living environments.

Lighting Attenuation Structures (LAS) are used at tunnel entrances to prevent direct sunlight from reaching the road surface, where strong luminance contrasts and glare can create unsafe visual conditions. Although their primary purpose is to block sunlight, LAS design is complicated by the changing position of the sun over time and by competing requirements related to spacing, material use, and visual performance. This work presents an analytical method for designing LAS geometries based on solar altitude and azimuth, with the aim of defining clear geometric limits for effective daylight control.

The method is built on explicit geometric relationships linking solar position, shadow length, and structural dimensions. These relationships are used to calculate the maximum allowable spacing between structural elements that still prevent direct sunlight penetration. By evaluating the equations using time‑dependent solar data, the analysis identifies critical periods when shadow coverage becomes insufficient, showing that certain sun positions cannot be fully addressed through simple overhead beams alone. This provides a clear justification for supplementary vertical or box geometries.

The work further extends the analytical approach to include solar panels as an integrated part of the LAS. Incorporating photovoltaic elements introduces additional geometric constraints, as shading strategies beneficial for daylight control may reduce power production for tunnel lighting. The method therefore treats shared shading conditions as a design parameter, allowing panel layouts and electrical zoning to be aligned with predictable shadow patterns. This reduces energy losses caused by partial shading and links solar power generation directly to the temporal availability of sunlight.

In addition to shading performance, the study evaluates road surface luminance beneath the LAS. Passive daylight contribution is assessed independently and compared to required threshold luminance levels, demonstrating that LAS systems—regardless of geometry—cannot meet safety requirements through daylight alone. Artificial lighting is therefore treated as a necessary complement rather than an optional addition, with the LAS reducing but not eliminating lighting demand.

Overall, the work provides a clear analytical framework for understanding how LAS geometry, solar shading, luminance performance, and integrated solar panels interact. It supports early design decisions, reduces reliance on trial‑and‑error simulation, and clarifies the limits of passive solutions in safety‑critical lighting environments.

Lighting quality is a critical component of indoor environmental quality in educational buildings, directly influencing user comfort, satisfaction, and productivity. This study evaluates and enhances indoor lighting performance within the library of the British University in Dubai (BUiD), in accordance with EN 12464-1 (2021) and LEED ID+C standards, by identifying performance gaps in existing lighting conditions.

A mixed-methods approach was adopted, combining quantitative and qualitative techniques through a case study methodology. Field measurements were conducted using a calibrated lux meter (Sekonic C-700), supported by user satisfaction surveys and simulation analysis using DIALux EVO software. Key performance indicators included illuminance (lux), Unified Glare Rating (UGR), and uniformity ratio, assessed across different lighting scenarios involving daylight and artificial lighting integration.

The results indicate that Strategy 3 (Scenario 1) integrating daylight with artificial lighting was the most effective approach. This scenario achieved an average illuminance level of approximately 650 lux, improved uniformity from 0.003 to 0.052, and maintained glare levels below UGR 19, ensuring compliance with visual comfort standards. In addition, significant energy savings were observed, with consumption reduced from 8987 kWh/year (base case) to 380 kWh/year under the optimized scenario.

The findings confirm that optimized integration of daylight and artificial lighting significantly improves visual comfort, energy efficiency, and user satisfaction in library environments. The study highlights the importance of user-centered lighting design and provides evidence-based guidance for sustainable lighting strategies in educational buildings.