BITS Faculty Publications
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Item Indoor plants’ effect on occupants’ performance, perceived comfort, and affect in an open-plan space in composite climatic regions, India(Elsevier, 2025-04) Dasgupta, Mani SankarBiophilic designs with indoor plants are being increasingly recognized for their potential to enhance indoor environmental quality (IEQ) and occupant satisfaction. This can contribute to sustainable and green buildings. However, evidence on the specific benefits of indoor plants remains ambiguous. Particularly, for the buildings in India, there is dearth of evidence of the impact of plants on occupants. We conducted a between-subjects study, with (WP) and without plants (WoP), to investigate effect of indoor plants on Indian building occupants in the composite climatic region of India. Subjective questionnaires queried participants’ indoor climate perception, sick building syndrome (SBS) symptoms, emotional state, self-assessed performance, and overall satisfaction with the space. Participants undertook a cognitive task targeting working memory (Operations Span). Air quality perception, SBS symptoms, and subjectively and objectively assessed performance did not differ significantly between WP and WoP groups. The WP group perceived the space to be better decorated (|r|, effect size = 0.42, p < 0.0001), cleaner (|r| = 0.16, p = 0.04), visually more comfortable (|r| = 0.22, p = 0.01), and cooler (r = 0.18, p = 0.02). The WP group also had enhanced positive emotions (|r| = 0.21 to 0.45, p < 0.0001 to 0.02) and reduced negative emotions (r = 0.18, p = 0.02). Our findings indicated that potted plants improved occupant perception of indoor environment and can potentially lower cooling energy use by over 8 %.Item Experimental Evaluation of Combined DCV and Economizer Cycle using a FLC Variable Air Volume (VAV) System(Taylor & Francis, 2016) Parameshwaran, R.A healthy indoor environment with sufficient fresh air is a prerequisite for the well-being and high productivity of building occupants. Carbon dioxide (CO2) based Demand Controlled Ventilation (DCV) optimizes and resolves the traditional conflict between reducing ventilation to save energy while maintaining adequate ventilation for air quality. Therefore, in conditioned spaces where occupancy levels vary, CO2based DCV can prove to be an energy efficient method for meeting ventilation needs while maintaining good IAQ. Furthermore, an economizer cycle can be used to save cooling energy. This design scheme takes advantage of cool weather conditions to supplement or satisfy the cooling load. When a Proportional-Integral-Derivative (PID) controller is used, it can respond only to linear variations using single input and single output operations. This can be improved by using a Fuzzy Logic Controller (FLC). This paper deals with the energy savings in a VAV air conditioning system achieved by combining DCV with an air conditioning economizer cycle incorporating FLC. The CO2 concentration and outside temperature are taken as input and damper angle as output for the FLC. Both laboratory measurements and simulations were made. Simulation was undertaken using MATLAB-Simulink. The potential energy savings of DCV combined with a temperature economizer cycle is in the range of 28% to 79% for VAV systems and 19% to 42% for CAV systems. The Indoor Air Quality (IAQ) is also maintained. An experimental test rig was developed and used to verify the performance of the system. This experimental work has been conducted to obtain the system’s response for design outdoor conditions.Item Effects of Indoor Plants on Occupants’ Emotional-State, Performance, and Perceived Comfort in an Open-Plan Seating Space(SSRN, 2023-09) Rai, Aakash Chand; Dasgupta, Mani SankarIndoor plants are a reliable means of introducing nature connection indoors, which can positively affect occupants’ well-being. To better understand the effectiveness of indoor plants on occupants’ well-being (perceived comfort, emotional state, and performance), we conducted a between-subjects study in a simulated open-plan seating space. Subjective questionnaires queried the occupants regarding their perception of indoor climate, sick building syndrome (SBS) symptoms, emotional state, self-assessed performance, and overall satisfaction with the space with and without indoor plants. The participants also undertook a cognitive task targeting working memory (operation Span). Participants in the group with plants (WP) rated the room to have better aesthetics (p = 0.004, r = 0.27), felt slightly cooler (p = 0.05, r = 0.18), and perceived less air dryness (p = 0.05, r = 0.18) than the group without-plant (WoP). Differences noted between the two groups’ perception of air quality, SBS symptoms, and their subjectively or objectively assessed task performance were not significant. The WP group had enhanced positive emotions (p < 0.0001 to 0.02, |r| = 0.21–0.45) and reduced negative emotions (p = 0.05, |r| = 0.18). Overall, our findings indicate that potted indoor plants positively impacted aesthetics, perceived thermal comfort, and mood in a simulated open-plan seating space.Item Effectiveness of plants for passive removal of particulate matter is low in the indoor environment(Elsevier, 2022-08) Rai, Aakash ChandParticulate air pollution is a major health concern and is responsible for about one in nine premature deaths worldwide. Significant exposure to particulate matter (PM) may happen indoors because people spend a large fraction of their time inside buildings. Indoor plants have been suggested as a potential solution for removing PM; however, their effectiveness has not been well characterized. We quantified the ability of eleven different plant species to remove airborne PM through experiments conducted in an environmental chamber. By introducing PM into the chamber and measuring its removal rate with and without the plants, we estimated plants’ deposition velocities and clean air delivery rates (CADRs).