Stratum ventilation shows the significant potential on energy conservation and indoor thermal comfort under cooling applications. Yet, only limited researches focus on the thermal performance of stratum ventilation under heating condition. The heating and cooling operation characteristic of stratum ventilation is different due to the distinct airflow characteristics. Therefore, this paper investigated the parameters that affect energy utilization efficiency and indoor thermal comfort under heating condition served by stratum ventilation via CFD simulations approach. The supply air parameters included temperature, airflow rate, angle, and return air outlet positions. The evaluation indicators adopt ventilation effectiveness and effective draft temperature (EDT) for assessing the energy utilization efficiency and indoor thermal comfort served by stratum ventilation under heating condition. The results demonstrated that, under the heating mode of stratum ventilation, different effects on the thermal performance were made by the mentioned parameters. The ventilation effectiveness was higher when the air supply temperature is 26°C, airflow rate is 7 air change per hour (ACH), and the air supply angle is 45°. The EDT range of the occupied zone is closest to zero K when the air supply temperature is 28°C, airflow rate is 12 (ACH), and the air supply angle is 60°. The related conclusions obtained from this study provide the theoretical basis for the stratum ventilation design and promote its heating application.

Green building development in China relies mainly on compulsory measures that lack incentive policies to motivate the enthusiasm of real estate developers. A floor area ratio bonus is encouraged by the Chinese State Council. In order to ensure the feasibility of a reward quota, residential buildings that met the requirement for energy efficiency during the official assessment in Ningbo in 2014 were selected as research objects. The amount of energy and water savings in terms of the Assessment Standard for Green Building is converted into carbon emissions. Carbon emissions of different star-rated green buildings are then measured in accordance with the actual water and power consumption of residential dwellings in 2014. A regression equation is set up concerning the floor area ratio and index for residential land per capita. A carbon emission-based method is proposed for measuring the reward quota associated with floor area ratio and recommendations are given for development using green building.

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The supply of fresh air for underground rail transit systems is not as simple as opening windows, which is a conventional ventilation (CV) measure adopted in aboveground vehicles. This study aims to improve contaminant dilution and air purification in subway car ventilation systems and the safety of rail transit post-coronavirus disease pandemic era. We designed an air conditioning (AC) terminal system combined with stratum ventilation (SV) to enable energy consumption reduction for subway cars. We experimentally tested the effectiveness of a turbulence model to investigate ventilation in subway cars. Further, we compared the velocity fields of CV and SV in subway cars to understand the differences in their airflow organizations and contaminant removal efficiencies, along with the energy savings of four ventilation scenarios, based on the calculations carried out using computational fluid dynamics. At a ventilation flow rate of 7200 m3/h, the CO2 concentration and temperature in the breathing areas of seated passengers were better in the SV than in the CV at a rate of 8500 m3/h. Additionally, the energy-saving rate of SV with AC cooling was 14.05%. The study provides new ideas for reducing the energy consumption of rail transit and broadens indoor application scenarios of SV technology.

With the implementation of clean heating and the outbreak of COVID-19, stratum ventilation with both energy-saving and healthy indoor environments has become a research hotspot. Room size dimension is one of the critical factors affecting the air distribution, thermal comfort, and ventilation performance of space heating, which is still a research blank at present. This study determined the applicable room size dimension of stratum ventilation for space heating by using a multi-criteria analytic hierarchy process-entropy weight (AHP-EW) model. A computational fluid dynamics (CFD) simulation verified by experiments was conducted. To investigate the ventilation performance of different room sizes in energy utilization and thermal comfort, airflow distribution, ventilation efficiency (Et), dimensionless temperature, effective ventilation temperature (EDT), air distribution performance index (ADPI), and predicted mean vote (PMV) were calculated. The multi-criteria AHP-EW method is used to evaluate every case comprehensively. The results show that the maximum room size obtained by multi-criteria APH-EW is 6 m, and considering the single criteria, the suitable height for stratum ventilation for heating is below 5.7 m. The data obtained in this paper can be used as a reference for further study on the application of stratum ventilation and heating in the future.