Green walls and living facades

The architecture researcher Yiming Shao had 43 people do desk work in three rooms in 2024, one with a living wall, one with a fake living wall and one with a bare white wall, recording EEG and heart rate variability throughout. Negative psychological states built up about three times more slowly with the real wall than in the plain office. After resting in the living-wall room people came back less alert and less focused, and Shao’s recommendation follows from it: put the wall in the rest area, not beside the desks.

The rest of this literature mostly measures the building. The building researcher Ibtihaj Alsadun ran two identical office rooms in Dhahran for twelve months in 2025, one of them retrofitted with a modular hydroponic green wall, with sensors on carbon dioxide, volatile organic compounds and PM2.5 and a sub-meter on the cooling. The green wall room used 13.5% less cooling energy across the year, 574.5 kilowatt hours, rising to 17.1% at the summer peak. Carbon dioxide fell 14.1% during occupied hours, volatile organic compounds 28.1% and PM2.5 20.9%. The economic case in that paper is modelled from published relationships rather than measured, which belongs in a different column from the sensor readings.

The architecture researcher Luciana Kristanto shaded a test office in a tropical climate with Vernonia elliptica at two foliage densities in 2026. At a leaf area index of 1.5 the glass luminance dropped by up to 56.1% while the daylight factor held at 6.2%, and glare was a Daylight Glare Index of 21.67, which rates as perceptible rather than disturbing.

The architecture researcher Fatemeh Delkhosh replaced the leaves with algae. Panels of spirulina at one part algae to 60 parts water left 85% of the office space glare-free across the year, and holding the density reached after a single day of growth raised that to 95.5%.

The process engineer Victor Pozzobon modelled the same idea across four American climate zones using five years of weather data. In hot dry conditions a microalgae biofacade raised the share of time with comfortable indoor humidity from 19.7 to 62.5%. In cold humid and hot humid zones it made no difference worth having, and the thermal gain over ordinary double glazing was 0.42 gigajoules per module per year.

4 of these 5 measure light, air, energy or humidity. Only Shao measured a person, and there were 43 of them.