Ismail, Muhammad Hanafi and Othman, Rashidi and Wan Sulaiman, Wan Syibrah Hanisah (2026) Evaluation of algal properties and chlorophyll content for light reduction in the built environment. In: INTERNATIONAL GAZİANTEP SCIENTIFIC RESEARCH CONGRESS-VII, 12-13 SEPTEMBER 2026, GAZİANTEP, TÜRKİYE.
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Abstract
The increasing demand for sustainable building technologies has encouraged the development of biological systems that can simultaneously contribute to environmental performance and building envelope functions. Microalgae and cyanobacteria are increasingly investigated for building-integrated photobioreactors because their pigmentation, biomass density, and photosynthetic activity can influence light transmission and shading while providing additional environmental benefits. Previous studies have established that light availability, photoperiod, pH, and cultivation conditions strongly influence microalgal growth, pigmentation, and photosynthetic performance. In building applications, these characteristics are particularly relevant because microalgal photobioreactors can act as dynamic shading elements and potentially modify solar radiation and visual conditions within buildings. This study investigated the effects of optimized pH and photoperiod conditions on the optical properties and chlorophyll content of four algal species, namely Pseudanabaena amphigramulata, Alkalinema sp., C. radiosa, and D. brasiliensis, with emphasis on their potential application for light-intensity reduction in the built environment. The algae were cultivated using BG11 under different pH and photoperiod conditions, and the optimum condition for each species was determined based on its growth performance. Colour characteristics were subsequently evaluated using the CIELAB system, including lightness (L*) and colour coordinate a*, using a Mettler-Toledo UV7 spectrophotometer. Chlorophyll content was determined spectrophotometrically after extraction using ethyl acetate and chloroform, with absorbance measured at 480, 648, and 666 nm. The results demonstrated distinct species-specific optical responses under optimized cultivation conditions. P. amphigramulata achieved its optimum condition at pH 8 and a 12-hour photoperiod, recording a green-intensity value (a*) of 52.27, lightness (L*) of 65.43, and chlorophyll content of 4.02. Alkalinema sp. recorded a* of 47.05, L* of 77.23, and chlorophyll content of 4.01 at pH 8 and an 18-hour photoperiod. C. radiosa and D. brasiliensis achieved optimum conditions at pH 10 and pH 8, respectively, with 24-hour photoperiods and chlorophyll contents of 3.95 and 3.75. Among the tested species, P. amphigramulata exhibited the lowest L* value and highest chlorophyll content, indicating a darker and more strongly pigmented biomass that may provide greater potential for solar-light attenuation. These findings suggest that species selection and optimization of cultivation conditions are important for developing algae-based shading components. The results provide an experimental basis for further investigation of microalgae photobioreactors as adaptive shading and light-management systems within sustainable building envelopes, particularly in tropical built environments.
| Item Type: | Proceeding Paper (Plenary Papers) |
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| Uncontrolled Keywords: | Microalgae, cyanobacteria, CIELAB, chlorophyll, light attenuation, photoperiod pH; building-integrated photobioreactor; built environment. |
| Subjects: | BPC Science and Technology in Islam G Geography. Anthropology. Recreation > GE Environmental Sciences N Fine Arts > NA Architecture > NA2542.35 Environmental aspect of architecture S Agriculture > SH Aquaculture. Fisheries. Angling > SH389 Fisheries-Algae and Algae Culture T Technology > TP Chemical technology > TP248.13 Biotechnology |
| Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button): | Kulliyyah of Architecture and Environmental Design > Department of Landscape Architecture |
| Depositing User: | Dr rashidi othman |
| Date Deposited: | 01 Oct 2026 16:31 |
| Last Update: | 01 Oct 2026 16:31 |
| Queue Number: | 2026-09-Q5367 |
| URI: | http://irep.iium.edu.my/id/eprint/131618 |
| Indexed In: | UNSPECIFIED |
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