Reserch On Renovation Scheme Design Of Cleaning Heating For Rural Schools Based On Indoor Thermal Environment Enhancement

In response to the increasingly serious air pollution,the state requires the Fenwei Plain to start air pollution prevention and control work.As one of the important cities in the Fenwei Plain,Xi’an has a high proportion of haze days throughout the year,and according to relevant data,winter heating is the main cause.Therefore,the clean heating pilot city construction project was launched in 2018.One of the important tasks is to carry out clean heating renovations in rural schools and improve the thermal environment in the classrooms in winter.Therefore,this paper uses a combination of on-site measurement,questionnaire survey and software simulation to study the clean heating renovation path of rural schools based on the improvement of thermal environment.(1)Through the survey of 93 existing rural school buildings in 7 outlying suburban counties in Xi’an,the typical rural school buildings and their heating status were summarized.A middle school in Huyi District was selected according to typical architectural features,and the indoor thermal environment in winter was studied by combining field measurements,questionnaire surveys and Airpak software simulation.Obtained that the existing school buildings in Xi’an rural areas have high heating energy consumption and the indoor thermal environment is not up to standard(the average temperature is low,the horizontal distribution is uneven,and the vertical temperature difference is large).The analysis reasons are: poor insulation performance of the envelope structure and inappropriate heating equipment And the layout is unreasonable.(2)In order to formulate a suitable renovation plan,firstly,based on the problems found in the actual measurement of the current situation,two evaluation indicators based on the thermal environment(average temperature and humidity,PMV-PPD,temperature uniformity index and vertical air temperature difference index)and energy-saving rate were selected.Then use theoretical analysis and orthogonal experiments to obtain suitable renovation strategies for exterior walls,exterior windows,heating equipment and their placement.Finally,two clean heating renovation plans with different applicability were proposed.The first renovation plan:the replacement of heating equipment with two 3k W air source heat pump hot air blowers;the second renovation plan: the exterior wall adopts 70 mm rock wool external insulation system,and the exterior windows are replaced with 5mm+9A+5mm plastic steel hollow glass windows,the outer door is replaced with an energy-saving outer door and two 3k W air source heat pump heaters are installed.(3)Using on-site measurements and De ST energy consumption simulation software,the indoor thermal environment improvement and energy-saving effects of different schemes were compared and evaluated before and after transformation.The second modification plan not only effectively improves the indoor thermal environment,but also enables the energy-saving rate to reach 30%.Therefore,it is recommended that the clean heating renovation path for school buildings in rural areas in Xi’an is the second renovation plan.That is,the outer wall adopts70 mm rock wool external insulation system transformation,the outer window is replaced with a 5mm+9A+5mm plastic steel hollow glass window,the outer door is replaced with an energysaving outer door,and two 3kW air source heat pump heaters are installed.