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Effects of urban green infrastructure (UGI) on local outdoor microclimate during the growing season.

Wang Y, Bakker F, de Groot R, Wörtche H, Leemans R - Environ Monit Assess (2015)

Bottom Line: The results showed that groves with high tree density (site B) have the strongest effect on microclimate conditions.This study showed that weather conditions can significantly impact the effectiveness of UGI in regulating microclimate.The results of this study can support the development of appropriate UGI measures to enhance thermal comfort in urban areas.

View Article: PubMed Central - PubMed

Affiliation: Environmental System Analysis group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands. feifeinetherland@hotmail.com.

ABSTRACT
This study analyzed how the variations of plant area index (PAI) and weather conditions alter the influence of urban green infrastructure (UGI) on microclimate. To observe how diverse UGIs affect the ambient microclimate through the seasons, microclimatic data were measured during the growing season at five sites in a local urban area in The Netherlands. Site A was located in an open space; sites B, C, and D were covered by different types and configurations of green infrastructure (grove, a single deciduous tree, and street trees, respectively); and site E was adjacent to buildings to study the effects of their façades on microclimate. Hemispherical photography and globe thermometers were used to quantify PAI and thermal comfort at both shaded and unshaded locations. The results showed that groves with high tree density (site B) have the strongest effect on microclimate conditions. Monthly variations in the differences of mean radiant temperature (∆Tmrt) between shaded and unshaded areas followed the same pattern as the PAI. Linear regression showed a significant positive correlation between PAI and ∆Tmrt. The difference of daily average air temperature (∆T a ) between shaded and unshaded areas was also positively correlated to PAI, but with a slope coefficient below the measurement accuracy (±0.5 °C). This study showed that weather conditions can significantly impact the effectiveness of UGI in regulating microclimate. The results of this study can support the development of appropriate UGI measures to enhance thermal comfort in urban areas.

No MeSH data available.


Related in: MedlinePlus

Box plot of ∆Ta for site A minus site B, site A minus site C, site A minus site D, and site A minus site E on cloudy and clear days from April to August 2014
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Fig10: Box plot of ∆Ta for site A minus site B, site A minus site C, site A minus site D, and site A minus site E on cloudy and clear days from April to August 2014

Mentions: Figure 10 compares ∆Ta (for site A minus site B, site A minus site C, site A minus site D, and site A minus site E) between daytime cloudy days and clear days. The weather condition was a significant factor explaining the differences in daily average Ta between tree-shaded areas (sites B, C, and D) and the unshaded area (site A) (p < 0.05 for all). It also explained the difference of daily average Ta between the open site A and site E (adjacent to the building façade) (p < 0.0005). When performing a KruskaleWallis H test for each month, as expected, the weather conditions had a significant impact on the differences of daily average Ta between tree-shaded areas and the unshaded area, but only during the period that trees had a high PAI (summer months). In contrast, weather conditions always played a crucial role in defining the difference of daily average Ta between sites A and E during the entire observation period (p < 0.05 for every month). Notably, on the cloudy days, the daily average Ta adjacent to the building (site E) was lower than the open space (site A), whereas on clear days, the values were opposite. Most likely, the building façade absorbs incident solar radiation and releases heat to the ambient environment.Fig. 10


Effects of urban green infrastructure (UGI) on local outdoor microclimate during the growing season.

Wang Y, Bakker F, de Groot R, Wörtche H, Leemans R - Environ Monit Assess (2015)

Box plot of ∆Ta for site A minus site B, site A minus site C, site A minus site D, and site A minus site E on cloudy and clear days from April to August 2014
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4636989&req=5

Fig10: Box plot of ∆Ta for site A minus site B, site A minus site C, site A minus site D, and site A minus site E on cloudy and clear days from April to August 2014
Mentions: Figure 10 compares ∆Ta (for site A minus site B, site A minus site C, site A minus site D, and site A minus site E) between daytime cloudy days and clear days. The weather condition was a significant factor explaining the differences in daily average Ta between tree-shaded areas (sites B, C, and D) and the unshaded area (site A) (p < 0.05 for all). It also explained the difference of daily average Ta between the open site A and site E (adjacent to the building façade) (p < 0.0005). When performing a KruskaleWallis H test for each month, as expected, the weather conditions had a significant impact on the differences of daily average Ta between tree-shaded areas and the unshaded area, but only during the period that trees had a high PAI (summer months). In contrast, weather conditions always played a crucial role in defining the difference of daily average Ta between sites A and E during the entire observation period (p < 0.05 for every month). Notably, on the cloudy days, the daily average Ta adjacent to the building (site E) was lower than the open space (site A), whereas on clear days, the values were opposite. Most likely, the building façade absorbs incident solar radiation and releases heat to the ambient environment.Fig. 10

Bottom Line: The results showed that groves with high tree density (site B) have the strongest effect on microclimate conditions.This study showed that weather conditions can significantly impact the effectiveness of UGI in regulating microclimate.The results of this study can support the development of appropriate UGI measures to enhance thermal comfort in urban areas.

View Article: PubMed Central - PubMed

Affiliation: Environmental System Analysis group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands. feifeinetherland@hotmail.com.

ABSTRACT
This study analyzed how the variations of plant area index (PAI) and weather conditions alter the influence of urban green infrastructure (UGI) on microclimate. To observe how diverse UGIs affect the ambient microclimate through the seasons, microclimatic data were measured during the growing season at five sites in a local urban area in The Netherlands. Site A was located in an open space; sites B, C, and D were covered by different types and configurations of green infrastructure (grove, a single deciduous tree, and street trees, respectively); and site E was adjacent to buildings to study the effects of their façades on microclimate. Hemispherical photography and globe thermometers were used to quantify PAI and thermal comfort at both shaded and unshaded locations. The results showed that groves with high tree density (site B) have the strongest effect on microclimate conditions. Monthly variations in the differences of mean radiant temperature (∆Tmrt) between shaded and unshaded areas followed the same pattern as the PAI. Linear regression showed a significant positive correlation between PAI and ∆Tmrt. The difference of daily average air temperature (∆T a ) between shaded and unshaded areas was also positively correlated to PAI, but with a slope coefficient below the measurement accuracy (±0.5 °C). This study showed that weather conditions can significantly impact the effectiveness of UGI in regulating microclimate. The results of this study can support the development of appropriate UGI measures to enhance thermal comfort in urban areas.

No MeSH data available.


Related in: MedlinePlus