Studies Of Solar Chimney For Ventilation And Energy-saving Efficiency In Low Energy Buildings

In the background of rapid economic growth,the problem of environmental pollution and increasing energy consumption in China has become increasingly serious.In China,building energy consumption accounts for about 1/3 of the total energy consumption.With the improvement of living standards,building energy consumption has continued to grow.In building energy consumption,air conditioning energy consumption accounted for 2/3.Therefore,how to reduce the refrigeration and heating energy consumption of the air conditioning system is an important research direction.Among the many methods to save energy,natural ventilation plays an important role in improving the indoor thermal environment.Natural ventilation can be generally divided into organized natural ventilation and unorganized natural ventilation.Organized natural ventilation is realized in the form of exhaust equipment in the building channels through which indoor air is discharged to the outside.It can effectively control the air flow.Solar chimney is a kind of device which can be used to strengthen and organize natural ventilation.Therefore,it is very important to study the natural ventilation effect and energy saving effect of a solar chimney to improve indoor thermal environment and save energy consumption.Based on theoretical calculation,numerical simulation and experimental research,this paper discusses the effect of solar chimney on strenthening natural ventilation and saving building energy,and the application of solar chimney in architectural design.Environmental research was based on the solar chimney device of P+ energy-saving building in East China.The experiment result was compared with the theoretical and numerical result in this study.The 0.02～0.45m/s air ventilation rate was measured,the solar chimney can bring a ventilation volumn of 70.6 m3/h-1887.6 m3/h on the measurement day.Based on the numerical simulation,the relationship between the size of a solar chimney and the ventilation effect was discussed.Results show that the solar chimney has direct relationship between natural ventilation and solar chimney size:ventilation volume increases when solar chimney height and width increases.There exsits a best depth-height ratio of 0.3～0.4 which can produce the largest amount of ventilation in solar chimney.The energy saving effect of the solar chimney is good,and its energy saving effect is positively correlated with the ventilation effect.Under the typical meteorological conditions of Shanghai,with the use of solar chimney,the annual energy saving rate of the case building reaches 12.9%.The energy-saving effect of a solar chimney is particularly notable during transition season.At the same time,this paper selects ten typical city in different thermal areas and discussed the energy-saving effect in different meteorological conditions.Results show that the solar chimney has a wide application prospect:In the ten cases,energy-saving rate under the use of solar chimney achieves from 6.6%to 51.1%.Data shows that the energy-saving effect of a solar chimney works best in mild areas,better than hot summer and cold winter,hot summer and warm winter areas,and aslo better than cold regions.At the end of this paper,the application of solar chimney in the architectural design is summarized:the facade of the building wall,combined with the construction of solar chimney;solar chimney with window atrium and solar chimney with the roof of the building.Taking Shanghai as an example,this artical discusses the suitble size of a solar chimney in architecture design.Recording to the simulation results,a comparison table of solar chimney’s size and the energy-saving effect is summerized.Architects can use this comparison table to define the size of a solar chimney when it is uesd in the preliminary design.