Growth light provision for indoor greenery: A case study

Adequate light provision for plants is essential when designing for indoor greenery, but there is a lack of knowledge with regards to lighting levels required for ornamental plants in the indoor environment. In practice, guidelines such as a lighting threshold of 1000 lx for indoor vegetated surfaces may result in over or under-compensation of lighting for plants. The objective of this study is to quantify the impact of growth light provision on indoor greenery. Field measurement was conducted in a building with extensive indoor greenery. A growth chamber study was also conducted to measure the whole-plant light compensation point (LCP) of two species of plants (Philodendron erubescens and Dracaena surculosa) used in the indoor greenery design. Results showed that LCP for both P. erubescens and D. surculosa was between 0.50 mol m−2 day−1 to 1.00 mol m−2 day−1. Onsite measurements of Photosynthetically Active Radiation (PAR) from 09:00 h to 18:00 h showed an excess of PAR arising from the combination of daylight and supplementary lighting, resulting in lighting over-compensation of approximately 0.56 mol m−2 day−1. However, this was not factored into the supplementary lighting plan, which specified a minimum lighting level of 1000 lx. Since electricity consumption is highly correlated with whole-plant LCP (R2 = 0.9989), significant savings in energy can be achieved by (1) determining actual lighting requirements for each plant and (2) measuring daylight availability onsite before installing greenery in the indoor environment.