Heat in courtyards: A validated and calibrated parametric study of heat mitigation strategies for urban courtyards in the Netherlands

Abstract

Outdoor thermal comfort in urban spaces is an important contributor to pedestrians' health. A parametric study into different geometries and orientations of urban courtyard blocks in the Netherlands was therefore conducted for the hottest day in the Dutch reference year (19 th June 2000 with the maximum 33°C air temperature). The study also considered the most severe climate scenario for the Netherlands for the year 2050. Three urban heat mitigation strategies that moderate the microclimate of the courtyards were investigated: changing the albedo of the facades of the urban blocks, including water ponds and including urban vegetation. The results showed that a north-south canyon orientation provides the shortest and the east-west direction the longest duration of direct sun at the centre of the courtyards. Moreover, increasing the albedo of the facades actually increased the mean radiant temperature in a closed urban layout such as a courtyard. In contrast, using a water pool and urban vegetation cooled the microclimates; providing further evidence of their promise as strategies for cooling cities. The results are validated through a field measurement and calibration.

Microclimate Improvement of Inner-City Urban Areas in a Mediterranean Coastal City

“…Similar to the aforementioned studies were the results of the Taleghani et al [61] study, which studied several microclimate interventions in an urban block courtyard with the least favorable orientation (i.e., in W-E axis). They reached the following conclusions: (1) the introduction of a water body at 65% of the total surface area decreased the ambient temperature and mean radiant temperature, (2) the combined use of trees, vegetation, and ground surfaces resulted in decreasing Shashua-Bar et al [84] studied two semi-closed courtyards in Negev, South Israel, which had the same orientation in the N-S axis, concrete pavements, and aspect ratio H/W = 0.5.…”

“…During the last decade, in a wide range of worldwide studies, the numerical model ENVI-met was commonly used for investigating microclimatic conditions in the urban environment [47,48,50,54,[57][58][59][60][61][62][63][64][65]. For instance, several studies have focused on: (1) investigating the Sustainability 2017, 9, 882 5 of 29 urban canyon microclimate [47,[57][58][59], (2) studying the effect of various parameters on the courtyards' microclimate, such as vegetation, paving materials, water bodies, and urban geometry [47,50,60,61], (3) studying the effect of urban morphology on the local microclimate and the human thermal comfort (calculating indexes as PMV) of various urban spaces [61][62][63][64], (4) investigating the microclimate and/or carrying out a parametric study on an urban neighborhood scale [48,54,[65][66][67], and (5) investigating the effect of green parks and vegetation on the local microclimate [49,59,68,69].…”

Correlations between GIS-Based Urban Building Densification Analysis and Climate Guidelines for Mediterranean Courtyards

“…Inner courtyards tempering properties have already been demonstrated by different authors in these dominant summer climates [14][15][16][17][18][19]40] and checked in the monitored courtyards at a single building scale. The maximum air temperature drop in the period recorded, was 6.7 • C. Therefore, at an urban scale, the city structure that implies a variable presence, AR and sizes of courtyards in these warm-climate cities depending on the specific climate has been also showed in this paper.…”

Review: Improving the Impact of Plant Science on Urban Planning and Design

“…Courtyards have been an important part of vernacular architecture in hot and arid climates for centuries and represent an environmentally positive method for providing thermal comfort [79]. Such strategies are now being re-visited with the renewed interest in passive cooling strategies [80,81]. Plant selection may be far more crucial when it comes to limiting heat gain to a building and cooling the outdoor temperature.…”