Solar-terrestrial radiant-energy regimes and temperature anomalies of natural and artificial turfs

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Artificial turf can develop unusually high surface temperature on hot sunny days. Solar and terrestrial radiant energy regimes as key determinants of thermal performance deserve detailed investigation. This study evaluated six components of the radiant-energy environment of a natural turf (NT) and a contiguous artificial turf (AT) sports fields in Hong Kong: direct solar, reflected solar, net solar, sky thermal, ground thermal, and net thermal. Temperature was monitored at five positions: air at 150 cm, 50 cm and 15 cm height, turf surface, and substrate. The experiment included four replications, namely two summer sunny days, and two duplicated instrument sets at each turf site. The two sites reacted very differently to the same intense daily sum of solar radiation input of 23.70 MW m⁻² with 9 h of bright sunshine (>120 W m⁻²), and daily sum of sky thermal radiation input of 38.59 MW m⁻². The maximum direct solar radiation reached 976.1 W m⁻² at 1245 h. NT albedo of 0.23 vis-à-vis AT of merely 0.073, and higher moisture content and specific heat of NT materials, presented critical differences. The hydrophobic and generally dry plastic (polyethylene) pile-fibers and black rubber-granule infill materials have low specific heat. Intense incoming shortwave and longwave radiation absorbed readily by AT materials raised turf surface temperature to 70.2 °C and substrate 69.3 °C, in comparison with <40 °C at NT. A cascading warming effect was triggered, beginning with low albedo, high net solar irradiance and low material specific heat, leading to heated AT materials, high ground-thermal radiation, and heat flux to near-ground air by conduction and convection. The ephemeral rainfall cooling confirmed ineffective cooling by irrigation. Athletes are immersed in an anomalously intense and omnidirectional radiant-energy and sensible-heat ambience. The heat-stress health implications of AT for athletes in hot summer afternoon call for preventive-precautionary measures and re-assessment of NT-to-AT decisions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)520-534
JournalApplied Energy
Volume173
Early online date20 Apr 2016
DOIs
Publication statusPublished - 01 Jul 2016

Fingerprint

temperature anomaly
Specific heat
albedo
energy
solar radiation
surface temperature
Heat radiation
Solar radiation
cooling
substrate
Temperature
shortwave radiation
air
longwave radiation
summer
infill
rubber
sport
Strategic materials
Cooling

Citation

Jim, C. Y. (2016). Solar-terrestrial radiant-energy regimes and temperature anomalies of natural and artificial turfs. Applied Energy, 173, 520-534. doi: 10.1016/j.apenergy.2016.04.072

Keywords

  • Natural and artificial turf
  • Solar and terrestrial radiation
  • Cascading warming effect
  • Substrate thermal mass
  • Substrate thermal inertia
  • Ephemeral rainfall cooling