An urban microclimate model is used to design a smart wetting protocol for multilayer street pavements in order to maximize the evaporative cooling effect as a mitigation measure for thermal discomfort during heat waves. The microclimate model is built upon a computational fluid dynamics (CFD) model for solving the turbulent air, heat and moisture flow in the air domain of a street canyon. The CFD model is coupled to a model for heat and moisture transport in porous urban materials and to a radiative exchange model, determining the net solar and thermal radiation on each urban surface. A two-layer pavement system, previously optimized for maximal evaporative cooling applying the principles of capillary pumping and capillary break, is considered to design a smart wetting protocol answering the questions “when,” “how much,” and “how long” a pavement should be artificially wetted. It was found for the current optimized pavement solutions that a daily amount of 6 mm wetting over 10 min in the morning, preferentially between 8:00 and 10:00, guarantees a maximal evaporative cooling for 24 h during a heat wave.
BarriopedroDFischerEMLuterbacherJ, et al. (2011) The hot summer of 2010: Redrawing the temperature record map of Europe. Science332(6026): 220–224.
3.
BłazejcżykKJendritzkyGBrödeP, et al. (2013) An introduction to the universal thermal climate index (UTCI). Geographia Polonica86(1): 5–10.
4.
BlockenBStathopoulosTCarmelietJ (2007) CFD simulation of the atmospheric boundary layer: Wall function problems. Atmospheric Environment41(2): 238–252.
5.
BouvierMBrunnerAAimeF (2013) Nighttime watering streets and induced effects on the surrounding refreshment in case of hot weather. The city of Paris experimentations. Techniques - Sciences - Methodes12: 43–52.
6.
CebeciTBradshawP (1977) Momentum Transfer in Boundary Layers. New York, NY: McGraw-Hill Book Co.
7.
CeliaMABouloutasETZarbaRL (1990) A general mass-conservative numerical solution for the unsaturated flow equation. Water Resources Research26(7): 1483–1496.
8.
ClarkRTBrownSJMurphyJM (2006) Modeling Northern Hemisphere summer heat extreme changes and their uncertainties using a physics ensemble of climate sensitivity experiments. Journal of Climate19(17): 4418–4435.
9.
CohardJMRosantJMRodriguezF, et al. (2018) Energy and water budgets of asphalt concrete pavement under simulated rain events. Urban Climate24: 675–691.
10.
ColeRJ (1976) The longwave radiative environment around buildings. Building and Environment11(1): 3–13.
11.
DefraeyeT (2011) Convective heat and mass transfer at exterior building surfaces. PhD Thesis, Katholieke Universiteit Leuven, Belgium.
12.
Della-MartaPMHaylockMRLuterbacherJ, et al. (2007) Doubled length of western European summer heat waves since 1880. Journal of Geophysical Research Atmospheres112(15): 1–11.
13.
FerrariAKubilayADeromeD, et al. (2020) The use of permeable and reflective pavements as a potential strategy for urban heat island mitigation. Urban Climate31: 100534.
14.
FialaDHavenithGBrödeP, et al. (2012) UTCI-Fiala multi-node model of human heat transfer and temperature regulation. International Journal of Biometeorology56(3): 429–441.
15.
FischerEMSchärC (2010) Consistent geographical patterns of changes in high-impact European heatwaves. Nature Geoscience3(6) 398–403.
16.
HagentoftCEKalagasidisASAdl-ZarrabiB, et al. (2004) Assessment method of numerical prediction models for combined heat, air and moisture transfer in building components: Benchmarks for one-dimensional cases. Journal of Thermal Envelope and Building Physics27(4): 327–352.
17.
HendelMColombertMDiabY, et al. (2014) Improving a pavement-watering method on the basis of pavement surface temperature measurements. Urban Climate10(P1): 189–200.
18.
HendelMColombertMDiabY, et al. (2015) An analysis of pavement heat flux to optimize the water efficiency of a pavement-watering method. Applied Thermal Engineering78: 658–669.
19.
HendelMGutierrezPColombertM, et al. (2016) Measuring the effects of urban heat island mitigation techniques in the field: Application to the case of pavement-watering in Paris. Urban Climate16: 43–58.
20.
JanssenHBlockenBCarmelietJ (2007) Conservative modelling of the moisture and heat transfer in building components under atmospheric excitation. International Journal of Heat and Mass Transfer50(5–6): 1128–1140.
21.
JanssenHCarmelietJHensH (2002) The influence of soil moisture in the unsaturated zone on the heat loss from buildings via the ground. Journal of Thermal Envelope and Building Physics25(4): 275–298.
22.
KubilayADeromeDBlockenB, et al. (2013) CFD simulation and validation of wind-driven rain on a building facade with an Eulerian multiphase model. Building and Environment61: 69–81.
23.
KubilayADeromeDCarmelietJ (2018) Coupling of physical phenomena in urban microclimate: A model integrating air flow, wind-driven rain, radiation and transport in building materials. Urban Climate24: 398–418.
24.
KubilayADeromeDCarmelietJ (2019) Impact of evaporative cooling due to wetting of urban materials on local thermal comfort in a street canyon. Sustainable Cities and Society49: 101574.
25.
LaunderBESharmaBI (1974) Application of the energy-dissipation model of turbulence to the calculation of flow near a spinning disc. Letters in Heat and Mass Transfer1(2): 131–137.
26.
LiHHarveyJTHollandTJ, et al. (2013) The use of reflective and permeable pavements as a potential practice for heat island mitigation and stormwater management. Environmental Research Letters8(1): 015023.
27.
MaillardPDavidFDechesneM, et al. (2014) Characterization of the Urban Heat Island and evaluation of a road humidification mitigation solution in the district of La Part-Dieu, Lyon (France). Techniques Sciences Méthodes6: 23–35.
28.
MoonenPDefraeyeTDorerV, et al. (2012) Urban physics: Effect of the micro-climate on comfort, health and energy demand. Frontiers of Architectural Research1(3): 197–228.
29.
NakayamaTFujitaT (2010) Cooling effect of water-holding pavements made of new materials on water and heat budgets in urban areas. Landscape and Urban Planning96(2): 57–67.
30.
Novatech (2010) 7th International Conference on Sustainable Techniques and Strategies for Urban Water Management, Lyon, France, 27 June–1 July.
31.
OpenFOAM (2018) OpenFOAM v6 User Guide. The OpenFOAM Foundation. Available at: http://www.openfoam.org
32.
ParisonSHendelMGradosA, et al. (2020) A lab experiment for optimizing the cooling efficiency and the watering rate of pavement-watering. Urban Climate31: 100543.
33.
QinY (2015) A review on the development of cool pavements to mitigate urban heat island effect. Renewable and Sustainable Energy Reviews52: 445–459.
34.
QinYHeYHillerJE, et al. (2018) A new water-retaining paver block for reducing runoff and cooling pavement. Journal of Cleaner Production199: 948–956.
35.
RichardsPJHoxeyRP (1993) Appropriate boundary conditions for computational wind engineering models using the k-ϵ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics46–47: 145–153.
36.
RobineJMCheungSLKLeRoyS, et al. (2008) Death toll exceeded 70,000 in Europe during the summer of 2003. Comptes Rendus Biologies331(2): 171–178.
37.
Rodríguez-VázquezMHernández-PérezIXamánJ, et al. (2020) Coupling building energy simulation and computational fluid dynamics: An overview. Journal of Building Physics44(2): 137–180.
38.
SaneinejadSMoonenPCarmelietJ (2014) Coupled CFD, radiation and porous media model for evaluating the micro-climate in an urban environment. Journal of Wind Engineering and Industrial Aerodynamics128: 1–11.
39.
SantamourisM (2013) Using cool pavements as a mitigation strategy to fight urban heat island: A review of the actual developments. Renewable and Sustainable Energy Reviews26: 224–240.
40.
StarkePGöbelPColdeweyWG (2011) Effects on evaporation rates from different water-permeable pavement designs. Water Science and Technology63(11): 2619–2627.
41.
TakahashiRAsakuraAKoikeK, et al. (2010) Using snow melting pipes to verify the water sprinkling’s effect over a wide area.
42.
WeiJHeJ (2013) Numerical simulation for analyzing the thermal improving effect of evaporative cooling urban surfaces on the urban built environment. Applied Thermal Engineering51(1–2): 144–154.
43.
WhitakerS (1977) Simultaneous heat, mass, and momentum transfer in porous media: A theory of drying. Advances in Heat Transfer13(C): 119–203.
44.
WieringaJ (1992) Updating the Davenport roughness classification. Journal of Wind Engineering and Industrial Aerodynamics41(1–3): 357–368.
45.
XieNAkinMShiX (2019) Permeable concrete pavements: A review of environmental benefits and durability. Journal of Cleaner Production210: 1605–1621.
46.
XuPWangLLiuY, et al. (2020) The record-breaking heat wave of June 2019 in Central Europe. Atmospheric Science Letters21(4): 1–7.
47.
YamagataHNasuMYoshizawaM, et al. (2008) Heat island mitigation using water retentive pavement sprinkled with reclaimed wastewater. Water Science and Technology57(5): 763–771.
48.
YasaE (2017) Microclimatic comfort measurements evaluation of building physics: The effect of building form and building settled area, on pedestrian level comfort around buildings. Journal of Building Physics40(5): 472–500.
