Research On The Application Of Combined System Of Solar Collector And Green Roof On The Plain Roof

This paper aims at finding out the energy performance of the building mounted with green roof and solar collector system on the flat roof.Firstly,this paper has classified the green roof and solar collector system into two categories that is the stacked and distributed type.Moreover,this paper has developed energy balance equations for each of them.Secondly,based on the deficiency and limits in the green roof research field,this paper proposed a method in calculating seasonal variable leaf area index(LAI).In most researches,due to lack of site-measurement resources and data,or lack of opportunity to do experiments,most green roof simulations only applied LAI for a rather short period.There rarely exists long-term simulation considering seasonal variable LAI into the green roof model.In reality,LAI varies seasonably.The inappropriate setting of LAI value could bring about some problems.In order to solve it,this paper has proposed an equation for the calculation of seasonal variable LAI,and also provide the temperature field in different climate zone like frigid zone,temperate zone,tropical and subtropical zone based on the three-base-point temperature of plant.After comparing with experiment test data,it is found that the new equation for calculating seasonal variable LAI has a better accuracy.Thirdly,according to the seasonal variable LAI equation,this paper also has added it into green roof model.By comparing the simulation result of seasonal green roof model with the measurement data,it is validated that the green roof model coupled with variable LAI equation is more adequate.Then,in order to find out the energy performance of different green roof,the simulation is conducted between green roof model with constant and variable LAI.Results show that seasonal variable LAI green roof model perform better.Lastly,in order to find out the performance of green roof and solar collector systems in different areas,this paper has carried simulation for them.The simulation is conducted with two concerns,which are the system types and climate conditions.Simulation results show that for heating load,the green roof or stacked type roof performs better than bare roof.And the heating load could be further reduced by adding more areas of green roof.For areas with a warm winter,building with stacked type roof saves more energy while for rest of the areas it is green roof.