Passive houses or the ultra-low energy buildings have been introduced into the practical operations, and these buildings require very little energy for space heating and cooling. With the time past, there were many researches and experience on the passive residential and office buildings but almost few have been done in the school buildings.
One school building with Passive House standard of the FOS/BOS Erding implemented with HVAC control systems was recently built up, which has adopted a novel heat recovery air conditioning system particularly operating in cold winter and hot summer. School building energy conservation performance and classroom air environment quality enhancement was simultaneously investigated in the present work. Heat recovery efficiency of the heat recov-ery facility and energy conservation ratio of the air conditioning unit were analytically mod-elled, taking the classroom ventilation network into account. Following that, classroom dis-placement ventilation and its thermal stratification have been investigated concerning the effects of delivering ventilation flow rate and supplying air temperature. Representative ther-mal comfort parameters, the percentage of dissatisfied, temperature difference between ankle and head, and draft dissatisfaction have been evaluated. Indoor air quality indicated by the CO2 concentration was also investigated in terms of different levels of ventilation flow rate. Classroom energy demands for ventilation and winter heating/summer cooling have shown that they decrease with the promotion of heat recovery efficiency of the ventilation facility, and the energy conservation ratio of the air conditioning unit increases/decreases with the promoting temperature of supplying fresh air in winter/summer. Detailed fitting cor-relations of heat recovery ventilation and air conditioning energy conservation have been presented. Numerical results indicated that the promotion of mechanical ventilation could simultaneously boost the dilution of indoor air pollutants and the non-uniformity of indoor thermal and pollutant distributions. The research illuminated that enhancement of class-room air quality and reduction of school building energy consumption could be simultane-ously achieved with the appropriate operation of heat recovery air conditioning and ventila-tion system.
In the transitional seasons, natural ventilation is an effective method to improve indoor air quality and reduce energy consumption in buildings, especially when the indoor temper-ature approaches closely to ambient level. Heat losses due to the opened windows and ventilation effectiveness ratio are analytically modelled. After air flow models were set up,
the effects of thermal buoyancy on the classroom airflow and thermal stratification comfort as well as the contaminant dispersion are numerically investigated and discussed. Natural ventilation of a classroom and its thermal stratification as well as indoor air quality indicated by the CO2 concentration have been investigated concerning the effects of supplying fresh air temperature and delivering natural ventilation flow velocity. Subsequent energy effi-ciency analysis illuminates that classroom energy demands for natural ventilation could de-crease with the promotion of the ventilation effectiveness ratio for heat distribution when the natural ventilation rate maintains a constant, and with the shrinking of the ventilation effec-tiveness ratio for heat distribution when the supplying air temperature is not changeable. Following that, detailed correlations of heat loss resulted from opened window and ventila-tion effectiveness of natural ventilation inside the classroom have been presented.
Building energy performance analysis based on the network model could dynamically identify the important parameters of building energy consumption and thermal environment such as HVAC energy demands, room air temperature and facade temperature, to name just a few. A sample test classroom and the whole passive school building, whose heat-ing/cooling and ventilation parameters were accurately known as prior, are analytically mod-elled. In order to fully investigate the energy performance of the sample test classroom and the whole building, six different classroom design points and three building scenarios have been representatively simulated respectively, depending on practical operational situations in this school building implemented with HVAC control systems. Heating/cooling and venti-lation energy demands of the sample test classroom and the whole building and thermal comfort inside the sample classroom have been evaluated regarding the effects of different indoor set-point temperatures in winter/summer, pre-ventilation in winter, the air exchange rates of night ventilation in summer, solar shading system, and the efficiency of the heat recovery facility. The subsequent analysis results indicate that the set-point combination 21.5/26 °C could be selected as a suitable set-point indoor temperature combination in win-ter/summer, which could not only meet the requirement of human thermal comfort, but also effectively reduce energy consumption. Moreover, the annual wall heating and pre-heating as well as active cooling demands are expectedly few. In addition, night ventilation in sum-mer could effectively result in cooling energy storage, which could provide more appropriate living conditions for the following day, and meanwhile it could greatly reduce energy costs for cooling at daytime. The optimized control systems for HVAC and sun-shading show an expectedly energy efficient performance.
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Passive houses or the ultra-low energy buildings have been introduced into the practical operations, and these buildings require very little energy for space heating and cooling. With the time past, there were many researches and experience on the passive residential and office buildings but almost few have been done in the school buildings.
One school building with Passive House standard of the FOS/BOS Erding implemented with HVAC control systems was recently built up, which has adopted a nove...
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