Effects of plant and substrate selection on thermal performance of green roofs during the summer
نویسندگان
چکیده
Green roof assemblies influence the total roof surface energy balance for a building. The energy balance for a green roof depends mostly on the selection of plants and substrates suitable for the building’s location. This study measured thermal properties of common green roof materials and selected two types of plants and substrates to simulate transient thermal performance of different green roof assemblies. The selected plants and substrates have the highest and lowest reflectivity values to establish upper and lower bounds of thermal performance. The simulations use a previously developed green roof model including weather data for four cities representing different climate zones in the U.S. Based on the simulations, substrate heat fluxes and net radiation fluxes are compared for five days in July of the typical meteorological year. The results show that green roof assemblies receive net radiation fluxes that differ by 20%, and peak net radiation fluxes that differ by 16%, due to their different spectral reflectivity values. However, the substrate heat fluxes are similar for different green roof assemblies, as a roof insulation layer diminished this flux. Overall, the material selection of green roof assemblies is more important for buildings located in climate zone 4 or 5 than buildings located in climate zone 2 or 3, where limited water availability for evapotranspiration during hot, dry summers results in little thermal performance variability. Independent of the climate zones, simulation results show that the plant type has an important effect on the net radiation. 2014 Elsevier Ltd. All rights reserved.
منابع مشابه
Study of thermal performance of building roofs in the city of Tehran
The design of a building can provide the highest thermal comfort in the interior without any mechanical equipment and save energy to a large extent. The roof of a building is an important part for thermal loss. This research studies the thermal performance of 14 conventional roof structures in Tehran city by using designbuilder 4.5. It is found that the polystyrene block performs best compared ...
متن کاملEnergy Conservation Potential of an Extensive Green Roof in Iran for One Year Duration
The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify energy problems in cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. There are some suggested ways to reduce these issues, among them vegetated roofs are shown...
متن کاملThermal Performance of Extensive Green Roofs in Cold Climates
Green roof is a specialized roofing system that supports vegetation growth on rooftops. This technology is rapidly gaining popularity in North America as a sustainable design option. Green roofs offer multiple benefits to urban areas such as reduction of heating/cooling needs for the building, urban heat island and stormwater runoff for the region. In this study, the performance of two extensiv...
متن کاملCladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo
Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats. They are able to survive extremely har...
متن کاملEvaluation of the Growth and Thermodynamic Properties of Frankenia on Different Growing Media in an External Green Wall
Currently, the idea of integrating nature and buildings through green roofs and green walls has been considered as a sustainable strategy in cities. However, studies on the substrates which allow the plants to fully establish in these systems are still lacking. It is also a challenge to find the substrates which provide the plants with proper growth, nutrition, and environmental sustainabilit...
متن کامل