Research On The Effect Of Coupled Heat And Moisture Transfer On Energy Consumption And Indoor Thermal And Moisture Environment Of Public Buildings

Building envelope is multi-layer porous structure.It transfers heat and moisture in the indoor and outdoor temperature difference and water vapor partial pressure difference.This is a typical coupled heat and moisture migration process.When the hole is filled with moist air,liquid water or ice,it will directly affect thermal properties of the material.According to moisture through the wall coming into indoor building,it will also affect indoor environment and energy consumption due to the formation of the latent heat.However,moisture transfer process in the building envelopes does not be taken into account in the current conventional thermal calculation and energy consumption analysis.In this thesis it is studied that coupled heat and moisture insulation wall of public building in different climate area.A series of hygric properties of five common building materials-EPS,rock wool,concrete,adhesive,rendering coat mortar are performed on the material level.First of all,the thermal conductivities of materials are tested by heat flow meter method and guarded-hot-plate method.Repeatability errors,reproducibility errors and systematic errors caused by thermal contact resistance are analyzed.Then we get accurate thermal conductivities of materials with the temperature and humidity variation.In addition,specific heat capacity of materials is obtained by mixed method.Cup tests get vapor permeability related with moisture content.Sorption isotherms are tested by static gravimetric tests.Water absorption coefficient,capillary saturation moisture content,liquid diffusivity are determined by capillary absorption tests.And vacuum saturation moisture content,open porosity,bulk density and skeletal density are measured by vacuum saturation tests.The thesis enriches the hygric properties database of common building materials in China.The indoor thermal comfort and building energy consumption of typical cities in different climate area-Harbin,Shenyang,Beijing,Shanghai,Guangzhou,Kunming are analyzed using single heat transfer CTF algorithm and dynamic heat and moisture coupled HAM algorithm by energy simulation software WUFI-Plus.It is discovered that coupled heat and moisture on building envelope impact on cooling and heating energy consumption,total annual energy consumption,indoor heat and moisture environment significantly.With the geographical location of the building from north to south,the effect of coupled heat and moisture on the building's annual energy consumption vary from positive to negative.For the EPS thermal insulation system,the impact extent ratio of coupled heat and moisture is from 6.97%to-2.49%.For the rock wool insulation system,the ratio of coupled heat and moisture is from 8.3%to-0.84%.Coupled heat and moisture transfer in the building envelopes should be considered at the time of air conditioning equipment model selection and environmental prediction analysis.Or it will cause air conditioning system efficiency decline,failed controlling and so on economic waste and comfort issues.Then,the influence of air conditioning operating modes,air change rate and moisture transfer of building envelope on indoor moisture environment are studied using HAM model.Study shows that humidity controlling mode of air conditioning equipment can reduce effectively high-moisture time.The time scale of relative humidity beyond 70%is delicined from 75%to 16%.Mechanical ventilation can reduce greatly indoor relative humidity,while reducing dehumidification latent heat load.The time scale of relative humidity beyond 70%is delicined from 79%to 25%.The larger air change rate is,the more dehumidifying effect is.Indoor average relative humidity improves obviously with considering moisture transfer of building envelopes.Moreover,coupled heat and moisture of building envelopes can effect prominently the calculation of building thermal and the prediction of building energy consumption,but it can't be popularized in engineering and virtual application in a short time due to abundant hygric properties of building materials and complicated heat and moisture calculation.Therefore,the current result of energy consumption can be modified by the correction factor of coupled heat and moisture.In conclusion,they are of great significance that achieving building energy efficiency and improving indoor heat and moisture environment by testing hygric properties,calculating accurately thermal transfer and analyzing heat and moisture transfer impact on energy consumption and indoor heat and moisture environment.