Study On Outdoor Calculation Parameters Of Natural Ventilation Thermal Design

With the rapid economic development of developing countries,the world’s energy consumption has shown a trend of rapid growth in recent years.At present,the global building energy consumption has reached 40% of the total energy consumption.The passive cooling technology of buildings is proposed under this premise.Natural ventilation as one of the most widely used passive cooling measures has been recommended as a preferred means of removing indoor heat in the Code for thermal design of civil buildings(GB50176-2016).In order to achieve a good natural ventilation effect,it is necessary to calculate the corresponding outdoor calculation parameters of natural ventilation design,including natural ventilation applicable period,natural ventilation design outdoor calculated temperature,outdoor calculated wind speed and outdoor calculated relative humidity.However,at present,there is no basis for calculating the outdoor calculation parameters of natural ventilation design in engineering,so the effect of natural ventilation can hardly meet the expectation.The climate varies greatly in different parts of China,and the thermal adaptability of the population also varies significantly.Therefore,it is necessary to put forward the outdoor calculation parameters of natural ventilation design that meet the actual conditions of the applicability of natural ventilation in different parts of China.This research is aimed at the problem of "lack of outdoor calculation parameters for natural ventilation design" in the Code for thermal design of civil buildings(GB50176-2016),based on several outdoor meteorological parameters that have the greatest influence on natural ventilation,based on the existing indoor thermal comfort model of natural ventilation rooms,and taking the building envelope into consideration,combined with the measured meteorological data of 30 years,the outdoor calculated parameters of natural ventilation design in 5 typical cities with 3 grades were obtained.The main research work and results are as follows:(1)through sorting out the design process of natural ventilation,cooling principle and action mode of the building,three most important outdoor meteorological parameters affecting the effect of natural ventilation-air temperature,wind speed and relative humidity were obtained;In natural ventilation room indoor thermal comfort model combing to select Evaluation standard for indoor thermal environment in civil buildings(GB50785-2012)are provided in the APMV compensation model and the wind speed model to calculate the natural ventilation design interior design reference,and take into consideration of the building model combined with heat balance temperature method to get the natural ventilation design outdoor temperature.(2)through the discrete analysis of meteorological data,the "accumulative frequency method" was proposed to solve the discrete problem of meteorological data in years,and the applicable period of natural ventilation was obtained by combining "ventilation days-cumulative frequency distribution graph".Based on the cumulative frequency method and with the combination of "5 days moving average method" to get the two based on the outdoor climate condition of natural ventilation design method for determining the calculation parameters,and two kinds of based on the needs of indoor thermal comfort of comfort and nighttime ventilation design,and application of five typical cities get the calculation parameters corresponding to the natural ventilation design of outdoor(contains a outdoor calculated parameters of comfortable ventilation design and nighttime ventilation design).(3)4 methods of five typical city outdoor calculated parameter values of the natural ventilation design itself is compared and its application in building model to calculate the indoor air temperature,respectively,and the corresponding model and the method to calculate the past 30 years,comparing the indoor thermal comfort temperature using the product of accumulated thermal comfort days and accumulated thermal comfort temperature differences for evaluation index got five cities most suitable for outdoor calculation parameter determination method and the corresponding parameter values;The above parameters are applied to the building model to calculate the minimum open area of natural ventilation rooms,and the "interior design temperature-minimum open area diagram of natural ventilation rooms" in 5 cities is obtained,which can be selected by architects.