Cooling The Cities. High Solar Reflective Building Materials. Authors: Mr. Francesco Favaro Watergy International Group Mr Prokopis Perdikis Abolin Co

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1 Cooling The Cities High Solar Reflective Building Materials Authors: Mr. Francesco Favaro Watergy International Group Mr Prokopis Perdikis Abolin Co

2 Introduction The microclimate in the cities is created and influenced by the interaction between natural and man-made factors. Natural factors refer to the prevailing climatic conditions, topography and water volumes while the man-made ones refer to the urban built environment and its characteristics, such as the buildings orientation and geometry, materials used, colours, anthropogenic heat and air pollution. The contribution of the outdoor spaces in the improvement of the urban microclimate is very important, and it has been underlined by many international charters concerning environmental issues (i.e. Agenda 21).

3 Urban Heat and Urban Heat Islands The most important factors are human activity, inappropriate building materials, and lack of vegetation o HUMAN ACTIVITY: the everyday activity of the population requires energy. As people use more air conditioning, they draw more electricity from the grid, which in turn compounds GHG emissions and raises the temperature further. o BUILDING MATERIALS: the use of non-pervious, dark colored, solar absorptive materials, transform the built environment into a heat emitter which can have a tremendous impact into city s thermal balance. The modified land surface in cities affects the storage and radiative and turbulent transfers of heat and its partition into sensible and latent components Intergovernmental Panel on Climatic Change

4 Urban City and Land Use Studies of a city s urban fabric indicate that about 60 percent of urban surfaces are covered by roofs or pavements. About 20 to 25 percent are roofs and 30 to 45 percent are pavements. Akbari, H. Rosenfeld, A., & Menon, S., (2009). Global cooling: Increasing world-wide urban albedos to offset CO2. Climatic Change 94 (3-4), within 50 years an estimated 80 percent of the world s population will live in an urban area.. Crutzen, P. J. (2004). New directions: The growing urban heat and pollution island effect impact on chemistry and climate. Atmospheric Environment, 38 (21), Replacing and upgrading roofs and pavements with more reflective materials could reverse this warming, turning urban surfaces into assets instead of burdens. Vegetated roofs, permeable pavements, and shade trees are other cooling strategies that are complementary with high solar reflective roofs and pavements

5 High Solar Reflective Materials High Solar Reflectance or Albedo High Infrared Emittance Less Heat Absorption Faster Heat Release Lower Surface Heat Built UP Less Heat Penetrates the Buildings Lower Air Temperature Improved Thermal Comfort Improved Ambient Air Quality

6 Uses Masdar Institute, Abu Dhabi Carrefour, Italy Private Villa, Dubai School building, Singapore Athens, Greece

7 Benefit in City Level The use of new suitable High Solar Reflective MATERIALS The use of suitable VEGETATION the reduction of anthropogenic heat Play a crucial role modifying significantly the microclimate and thus the thermal comfort conditions. A comprehensive strategy to improve the microclimate in city scale requires an integrated scientific project where every intervention has been studied and evaluated. Empirical and partial interventions of local character, without comprehensive dimension, will have minimum contribution even if they are into the right direction.

8 Athens Case Study 1# CITY LEVEL ATHENS HEAT ISLAND EFFECT: Depiction of Existing Situation and Proposals* Climate of Athens = hot summers Physical layout and Topography= urban density and high buildings inappropriate materials and few green open spaces *Author: A. Tsolaki Bioclimatic Architect

9 Interventions Athens Case Study 3# Preservation and restoration with HSR materials for roofs and walls and the surrounding open space. NEW PEDESTRIAN TRACKS - INCREASE VEGETATION - USE OF HSR MATERIALS SHADED OPEN SPACES - WATER ELEMENTS - GREEN ROOFS - GREEN CARPETS

10 Athens Case Study 4# Simulation Programs Evaluation of proposed climate and architectural interventions to improve the microclimate performed with computational fluid dynamics CFD models: o PHOENICS and o ENVI-MET able to portray the physical and chemical processes in the atmosphere at various scales. - Small Scale= 2 mm 1 km! Using computer models provide valuable information especially for urban areas, where the flow of the wind, characteristics of turbulence and the meteorological factors (temperature, humidity, etc.) affected by the existence of buildings The purpose was to evaluate the wind flow field and temperature in the area, after the application of techniques to improve microclimate.

11 Athens Case Study 5# Evaluation of proposals for improving the microclimate Comparing the results of the new and the current situation there is a significant reduction in ambient temperature on average 2 C. The improvement of the microclimatic characteristics it is worth mentioning: Thermal comfort Improvement Reduce of Energy consumption for cooling There is a remarkable reduction of surface temperatures, after the application of the architectural interventions, of about 10 C on average. Surface Temperature after the application of the proposed interventions

12 Carrefour Case Study Hypermarket Carrefour Assago Milan Italy Date: 14/07/2011 Place: Assago Milan Italy Total Roof Surface: Sqm Flat Roof Covered with Gray PVC Application: HSRS Walkable Without Cool Barrier Roof System 2007: kwh, 2008: kwh, 2009: kwh 2010: kwh Average: kwh With Cool Barrier Roof System 2011: kwh BUILDING LEVEL We are about 29% reduction in electricity consumption for air conditioning Around savings per year Energy Manager: Mr. Giovanni Piano

13 Thank You Very Much! *Contact: Mr. Francesco Favaro Watergy International Group