Introduction
During the last century, huge movements of people have been observed
between rural and urban habitats. Currently, about 50% of the world
population lives in urban areas [4]. With the
increase of people in cities, the so-called urban heat island (UHI)
effect has become a bigger and bigger problem for health and comfort.
Indeed, urban materials like asphalt and concrete trap heat fluxes
inside the urban centres. [2] This effect increase
locally the temperature, which may lead to several hazards, particularly
during summer [1]. A huge amount of studies has
tried to describe the role of green roofs as a solution against the heat
effect (e.g. Takebayashi &
Moriyama, 2007[5], Kleererkorper et al,
2012[3], Zinzi & Agnoli,
2012[7], Susca et al,
2011[6]). Among others, Takebayashi & Moriyama
proved by measuring experimental data that the heat flux on green
(vegetalized) surfaces would be significantly smaller than on a grey one
[5]. Vegetation may then have a reducing effect on
heat increase. Susca et al (2011) studied the effect of vegetation and
green roofs against UHI in the city of New-York, USA, and used some
monitoring stations spread in the city to obtain measures during a
complete year. They demonstrated the advantages of having green roofs
against UHI, but also for biodiversity and air quality improvement
[6]. In this paper, we will focus on the city of
Geneva, Switzerland. We will try to measure a reduction of heat
measurement in the locations where a green surface is present, and
confirm the propositions made previously.