Effects of individual trees on the solar radiation climate of small buildings

Abstract

Heisler, O.M., 1986. Effects of individual trees on the solar radiation climate of small buildings. Urban Ecol., 9 : 337-359. Under clear skies, a mid-sized sugar maple tree (Acer saccharum Marsh.) reduced irradiance in its shade on a south-facing wall by about 80% when in leaf, and by nearly 40% when leafless. Reductions by a similar-sized London plane (Platanus acerifolia W.) were generally slightly smaller. The percentage reductions varied with the fraction (DR) of diffuse radiation, and could be approximated by regressions with DR' as the independent variable. The significance of the irradiance reductions (or building radiation climate was tested by using physical models of representative tree crowns (similar to sugar maple) and a representative house to evaluate shadow patterns, along with a mathematical model of average hourly solar radiation for an average day of each month. For a mid-sized tree with a 2-m clear bole located south of the house in a cloudy climate, the ratio of desirable insolation reductions during the cooling season to undesirable insolation reductions during the heating season was a low 0.74; whereas, with the same tree on the west, the ratio was a much more beneficial 4.6. In a surmy climate, the ratios were 0.55 and 3.3 for the tree on the south and west, respectively. A tai1er tree with a longer clear bole on the south produced more favorable ratios of cooling season to heating season insolation reductions than the tree with the short clear bole on the south.

Trees in Canadian Cities: Indispensable Life Form for Urban Sustainability

“…Due to their built infrastructure, cities frequently experience higher temperatures than the surrounding countryside-this is the urban heat-island effect [50]. Trees reduce ambient air temperatures by altering wind speeds, shading surfaces, and blocking solar radiation [51,52]. Trees also transpire water vapour into the air and, thus, cool it [53,54].…”

“…While we generally think of street trees as cooling agents, they also have the potential locally to increase air temperatures. For example, a canopy of immature trees can block airflow but still allow solar radiation to strike and heat the ground [51].…”

Demand for urban forests in United States cities

“…Trees in urban landscapes moderate temperature and microclimates, thereby reducing the need for air conditioning and thus saving energy (Heisler, 1986;McPherson, 1990;Meier, 1991;Oke, 1989). Urban trees help improve air quality and sequester carbon (Nowak, 1993;Nowak and McPherson, 1993;Rowntree and Nowak, 1991;Smith, 1981), help stabilize soils, reduce erosion, improve groundwater recharge, control rainfall runoff and flooding (Sanders, 1986), reduce urban noise levels (Cook, 1978), and provide habitat that increases biodiversity (Johnson, 1988).…”

Análisis de la radiación solar directa en las calles de Barcelona, en base a la relación entre su morfología y vegetación

“…En cuanto a los artículos y libros de investigación consultados, realizados de 1976 a 2014 cabe destacar los siguientes: "The distinction between canopy and boundary-layer urban heat islands" (Oke, 1976), "Canyon geometry, street temperatures and urban heat island in Malmö, Sweden" (Bärring, Mattsson y Lindqvist, 1985), "Effects of individual trees on the solar radiation climate of small buildings" (Heisler, 1986), "Street design and urban canopy layer climate" (Oke, 1988), "Street design and urban canyon solar access" (Arnfield, 1990), "La reconciliación de la escala urbana" (Echave Martínez, 2006), "Las escalas de luz" (Beckers, 2009a), "Effects of canyon geometry on outdoor thermal comfort: a case-study of hight-density, warm-humid climate" (Sharmin & Steemers, 2013), "Street design and urban microclimate: Analyzing the effects of street geometry and orientation on airflow and solar access in urban canyons" (Shishegar, 2013), "La influencia de la configuración de los cañones urbanos en el confort del peatón" (Alicia, Lusett y Izaguirre, 2013), "Practical issues for using solar-reflective materials to mitigate urban heat islands" (Bretz, Akbari & Rosenfeld, 1998), "Human thermal comfort below the canopy of street trees on a typical Central European summer day" (Mayer et al 2009), "Effects of asymmetry, galleries, overhanging facades and vegetation on thermal comfort in urban street canyons" (Ali-Toudert y Mayer, 2007), "Solar energy as a design parameter in urban planning" (Kanters & Horvat, 2012), "El efecto del confort térmico producido por la especie arbórea Almez en el espacio público" (Rojas-Cortorreal, Roset, Jaime, et al 2016a); así como los libros: "Boundary layer climates" (Oke, 1978), "Arquitectura y energía natural" (Coch Roura y Serra Florensa, 1995), "Enviromental site layout planning: solar access, microclimate and passive cooling in urban areas" (Littlefair et al 2000), "Evaluation of vegetation in urban space. Barcelona base model and propose to Dominican Republic" (RojasCortorreal, Roset, Jaume, et al 2016b).…”