The GREENROOF module (v7.3) for modelling green roof hydrological and energetic performances within TEB

Abstract

The need to prepare cities for climate change adaptation requests the urban modeller community to implement within their models sustainable adaptation strategies to be tested against specific city morphologies and scenarios. Greening city roofs is part of these strategies. In this context, a GREENROOF module for TEB (Town Energy Balance) has been developed to model the interactions between buildings and green roof systems at the scale of the city. This module allows one to describe an extensive green roof composed of four functional layers (vegetation – grasses or sedums, substrate, retention/drainage layers and artificial roof layers) and to model vegetation-atmosphere fluxes of heat, water and momentum, as well as the hydrological and thermal fluxes throughout the substrate and the drainage layers, and the thermal coupling with the structural building envelope. TEB-GREENROOF (v7.3) is therefore able to represent the impact of climate forcings on the functioning of the green roof vegetation and, conversely, the influence of the green roof on the local climate. A calibration exercise to adjust the model to the peculiar hydrological characteristics of the substrates and drainage layers commonly found on green roofs is performed for a case study located in Nancy (France) which consists of an extensive green roof with sedums. Model results for the optimum hydrological calibration show a good dynamics for the substrate water content which is nevertheless under-estimated but without impacting too much the green roof temperatures since they present a good agreement with observations. These results are encouraging with regard to modelling the impact of green roofs on thermal indoor comfort and energy consumption at the scale of cities, for which GREENROOF will be running with the building energy version of TEB, TEB-BEM. Moreover, the green roof studied for GREENROOF evaluation being a city-widespread type of extensive green roof, the hydrological characteristics derived through the evaluation exercise will be used as the standard configuration to model extensive green roofs at the scale of cities

Evaluating the impacts of greening scenarios on thermal comfort and energy and water consumptions for adapting Paris city to climate change

“…In this configuration TEB is run in offline mode (i.e. with 1D meteorological forcings as opposed to coupled to an atmospheric model), at the spatial resolution of 1 km, and with most of its parameterizations activated to allow for more physical processes and interactions to be accounted for: vertical turbulent diffusion within multilayer urban canyons (Hamdi and Masson, 2008;Masson and Seity, 2009), building energetics (Bueno et al, 2012;Pigeon et al, 2014), urban vegetation on the ground (Lemonsu et al, 2012), greenroofs (de Munck et al, 2013a), as well as a module for computing thermal comfort indexes (Fiala et al, 2012;Pigeon, 2011). In addition, the urban weather generator (UWG) implemented in SURFEX is applied in order to derive a 2D temperature forcing from a 1D forcing and city features (Le Bras and Masson, 2015).…”

Anthropogenic meso-meteorological feedbacks: a review of recent research

“…При этом ночная реакция приземной температуры воздуха, например, в мегаполисе Осака, может в несколько раз превышать ее реакцию днем даже при уменьшении AHF [105,107]. Многие авторы связывают усиление роли AHF ночью с подавлением вертикального перемешивания и уменьшением толщины ABL [108], однако частично это может быть связано и с исчезновением ночью влияния солнечной радиации.…”

“…Для моделирования таких процессов существующие модели городского каньона дополняются блоками на поверхности крыш и пространства между ними. Реализация таких моделей для расчетов действия на энергетический баланс зданий и температуру атмосферы внутри UCL эффектов озеленения крыш была осуществлена в [108,123], эффектов солнечных элементовв [124].…”

Validation hydrologique d'un modèle hydro-microclimatique urbain (TEB-Hydro) : analyse de sensibilité sur le bassin versant de Rezé (Nantes, France)

“…Il représente la ville de manière simplifiée en se basant sur l'approche de la rue canyon d'Oke [1987]. L'introduction de la végétation s'est concrétisée par le modèle TEB-Veg qui prend en compte : i) la végétation à l'intérieur de la rue et des espaces verts urbains [Lemonsu et al, 2012] avec le modèle ISBA [Boone et al, 1999], ii) les toitures végétalisées dans l'aménagement urbain [De Munck et al, 2013], iii) la végétation haute à l'intérieur de la rue [Redon et al, 2017].…”