Roof-integrated dew water harvesting in Combarbalá, Chile Danilo Carvajal, Jean-Gabriel Minonzio, Elvira Casanga, Jorge Muñoz, Alvaro Aracena, Sonia Montecinos and Daniel Beysens ABSTRACT Dew harvesting can be a supplementary source of freshwater in semiarid and arid areas. Several experiments on small-scale dew condensers (usually of 1 m 2 ) have been carried out in many places in the world; however, few experiments have been conducted on large-scale collectors integrated into buildings. This work aims to assess one year of dew water harvesting in Combarbalá (Chile) using a painted galvanised steel roof as collecting surface. The roof (36 m 2 ) was coated with a high- infrared-emissivity paint containing aluminosilicate minerals (OPUR, France). Dew measurements were conducted daily from September 2014 to August 2015. The dew yield and its relationship with meteorological variables were analysed. The results show that despite the low nocturnal relative humidity throughout the year (average: 48%), dew collection occurred on 56.1% of the recorded days. The daily average collection rate was 1.9 L d 1 , with a maximum of 15 L d 1 . The maximum daily dew yield is correlated strongly with relative humidity and correlated weakly with air temperature and wind speed. Considering the same rooftop can collect dew and rain, it was estimated that over one year dew water could contribute to roughly 8.2% of the total water collected, considering both sources. Danilo Carvajal (corresponding author) Instituto de Investigación Multidisciplinario en Ciencia y Tecnología, Universidad de La Serena, Benavente 980, La Serena 1720170, Chile E-mail: decarvajal@userena.cl Danilo Carvajal Jean-Gabriel Minonzio Jorge Muñoz Daniel Beysens International Organization for Dew Utilization (OPUR), 60 rue Emeriau, Paris 75015, France Jean-Gabriel Minonzio Sorbonne Université, CNRS UMR 7371, INSERM UMR S1146, Laboratoire d’Imagerie Biomédicale, LIB, F-75006, Paris, France Elvira Casanga Club de Adulto Mayor Nuevo Despertar de Quilitapia, Calle Unión s/n, Combarbalá, Chile Jorge Muñoz Municipality of Combarbalá, Plaza de Armas 438, Combarbalá 1890317, Chile Alvaro Aracena Escuela de Ingeniería Química, Pontificia Universidad Católica de Valparaíso, Av. Brasil 2162, Valparaíso 2362854, Chile Sonia Montecinos Departamento de Física y Astronomía, Facultad de Ciencias, Universidad de La Serena, Av. Juan Cisternas 1200, La Serena 1720236, Chile and Centro Estudio Recursos de Energía, Universidad Arturo Prat (CERE - UNAP), Avenida Arturo Prat 2120, Iquique 1110939, Chile Daniel Beysens Physique et Mécanique des Milieux Hétérogènes, UMR 7636 CNRS — ESPCI — Université Pierre et Marie Curie — Université Paris Diderot, PMMH-IPGP, 1 rue Jussieu 75005 Paris, France Key words | atmospheric water, dew collection, radiative cooling, water resources INTRODUCTION The availability of freshwater has become a serious problem in arid and semiarid areas of the world. This phenomenon has been aggravated by population growth and industrial activities (UNDP ). As a consequence, various technol- ogies have been developed to obtain freshwater from unconventional sources, such as seawater and brackish 357 © IWA Publishing 2018 Journal of Water Supply: Research and Technology—AQUA | 67.4 | 2018 doi: 10.2166/aqua.2018.174 Downloaded from http://iwaponline.com/aqua/article-pdf/67/4/357/248610/jws0670357.pdf by guest on 16 November 2022