The Effects of Indoor Living Walls on Occupant Thermal Comfort in Commercial Buildings

Abstract

Indoor living wall systems provide passive cooling through evapotranspiration and benefit occupants’ comfort. However, there is a lack of studies on quantifying the impact of indoor living walls on occupant satisfaction and thermal comfort. A thermal comfort study was designed for a hydroponic indoor living wall size of 25% leaf-to-floor area ratio (LFAR) at seven different room temperatures between 23 – 27C. Surveys on participants’ thermal comfort were collected in the comparison study for the space with and without the living walls. We found that occupants’ thermal comfort is enhanced with the presence of indoor living wall systems. Thermal sensation votes (TSV) were 0.47 lower on average with the living wall compared to without, which is equivalent to 1.40 °C ambient temperature reduction (ASHRAE/CBE comfort tool). There was a 15% reduction in participants preferring a “cooler” environment with the presence of living walls. We also found the difference between male and female TSV shrinks by 0.20 with the living walls (equivalent to 0.60 °C ambient temperature difference). Occupants can adapt to and endure higher temperatures based on our thermal comfort experimental results. With the presence of indoor living walls, the cooling setpoint can be increased by 0.74℃ (1.34℉) and 0.89℃ (1.61℉) for 90% and 80% thermally acceptable range.  As a novel feature of contemporary commercial buildings, indoor living wall systems would have a positive impact on energy efficiency and sustainability.

Keywords: Indoor Living Walls, Thermal Comfort, Commercial Buildings, Subjective Responses