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Graphical Abstract:

The development of low-carbon buildings represented by ultra-low energy consumption buildings has attracted worldwide attention, however the application law and energy-saving potential of night ventilation scheme in ultra-low energy consumption buildings have not been discovered as clearly as traditional buildings. To explore its feasibility and specific technical solutions, the night ventilation scheme of an ultra-low energy consumption building in Shenyang, China is optimized and analyzed. This building with mechanical ventilation and natural ventilation were studied by means of experiment and numerical simulation. Different night ventilation schemes including ventilation volume, frequency, duration and outside weather conditions were considered in the further simulations. The results show that the peak temperature in the ultra-low energy living room is clearly lower than the peak outdoor temperature, and both the peak indoor temperature and the cooling load of the building decrease with the increase of ventilation volume. The optimal night ventilation scheme for the building varies from month to month. The optimal ventilation frequency range is 4–12 times/h for mechanical ventilation. Under the optimized night ventilation mode, the building cooling system energy saving rate increases from June to September with an exception of July, for which the energy saving effect is not obvious under the mechanical ventilation scheme. In addition, the energy saving effect of natural ventilation scheme is better compared with mechanical ventilation. Application of night ventilation in ultra-low energy consumption buildings in Shenyang can greatly reduce the energy demand of the building cooling system. Under the optimized scheme, the annual energy saving is 11.96 kWh/m2. When the outdoor temperature is suitable, it is recommended to adopt natural ventilation at night to achieve better energy saving effect of the cooling system.

The two-spotted spider mite, Tetranychus urticaeKoch, is one of the most harmful pests in many agroecosystems worldwide. To effectively manage this pest, there is an urgent need to develop novel bio-active acaricides that support integrated pest management strategies targeting T. urticae. In this study, we explored the acaricidal effects of xenocoumacin 1 (Xcn1) on T. urticaeand its predator Neoseiulus californicususing the highly purified compound. Xcn1 was extracted and purified from the cell-free supernatant of the Xenorhabdus nematophilaCB6 mutant constructed by the easy promoter activated compound identification (easyPACId) method. When the concentration of Xcn1 exceeded 100 μg mL-1, the survival rate of spider mite adults declined to below 40% and the fecundity was decreased by 80% at six days post application. At concentrations of 25 and 50 μg mL-1, Xcn1 significantly impeded spider mite development by inhibiting the molt. However, neither concentration had any adverse effects on the survival or reproduction of the predatory mite N. californicus. The results from laboratory and semifield experiments consistently demonstrated the effectiveness of the antimicrobial metabolite Xcn1 in controlling pest mites at both the molecular and physiological levels. Our study offers a promising possibility that combines the compatible biocontrol agents of Xcn1 and predatory mites for integrated pest mite control.