In recent years, rapid urban development has led to capsule hotels, sleep pods, and other tiny sleeping spaces that adapt to people’s fast-paced lives, achieving maximum functionality with a very small footprint. However, due to the small space, human metabolic pollutant (such as CO₂) is more likely to accumulate, and the air is not easily circulated. In this paper, a full-size experimental platform is set up with three types of ventilation modes to explore the exclusion efficiency of metabolic pollutants and the overall distribution of age of air under these ventilation modes. The conclusions showed that the mean values of metabolic pollutant exclusion rates for the different ventilation modalities varied very little across the spatial dimensions of the confined space but varied considerably in the area around the head. The double-side attached ventilation method was the most effective in removing human metabolic pollutants, especially in the head region (CN ≥ 0.92), while the single-wall attached ventilation method had the best air exchange efficiency (η ≥ 0.85). This suggests an inconsistent distribution of CO₂ and age of air, which is contrary to general common sense. The conclusions of this paper can guide the design of ventilation for tiny sleeping spaces.

Sentry buildings have windows that are often open to facilitate communication between personnel. It also provides the possibility for the intrusion of pollutants such as vehicle exhaust emissions. To prevent the intrusion of outdoor pollutants and create an excellent indoor environment, internal circulation with double-attached ventilation (IC-DAV) and external circulation with double-attached ventilation (EC-DAV) are proposed for such buildings, and the isolation effect of two attached ventilation modes on pollutants is compared with that of natural ventilation. A computational fluid dynamics (CFD) method was used to simulate the transportation process and indoor distribution of outdoor pollutants intruding into sentry buildings from the regular openings under different outdoor wind directions, wind velocities, and states of the doors and ventilation modes. The results indicate that the leeward airflow of the three wind directions caused the largest pollutants to invade the room. The amount of pollutants intrusion increased with increasing wind velocity. When the leeward airflow and the windward airflow blow through the building, opening the door increased the amount of pollutants intruding into the room by 3.34 times and 8.85 times, respectively, compared with closing the door. However, the IC-DAV can isolate 81.7% of the pollutants while the EC-DAV can isolate 99.92% of the pollutants as compared with natural ventilation. Applying double attached ventilation mode in buildings can effectively prevent the intrusion of outdoor pollutants into the room, reduce the harm of outdoor pollutants to the health of indoor personnel, and provide a new idea for buildings to improve the indoor air quality.

With the emergence of urban sentry boxes and capsule hotels, the development of tiny spaces with the concept of a reasonable minimum occupied space has attracted widespread attention from society. The ventilation mode that fits with the limited geometric characteristics of tiny spaces is worth exploring. Combined with the respective ventilation requirements of two types of tiny spaces, i.e., sentry box space and tiny sleeping space, this paper proposes two attached ventilation modes. A full-scale experiment cabin was established, and the simulation method was optimized through experimental data. The airflow pattern and distribution performance of the two attached ventilation modes in two types of tiny spaces were studied by the CFD method. The results showed that the airflow attached to the vertical wall could form an air curtain at the opening windows of the sentry box space, but there is a phenomenon of air leakage. The installation of the deflector can improve the integrity of the air curtain, and the best installation angle of the deflector is 60 degrees. The double side-attached ventilation mode in the tiny sleeping space can not only relieve the draught of the occupants (DR < 15%), but also firstly deliver fresh air to the occupied zone (expiratory zone MAA < 92 s). The research conclusions will add new ideas to the diversity of ventilation modes in tiny spaces.

Based on the structural characteristics of existing buildings and the disadvantages of current mixed ventilation mode in the application to large space buildings, an original column attachment ventilation (CAV) has been proposed. In this study, the experiment utilized a room space with four columns uniformly distributed in the space to visualize the movement of attached airflow along the cylinder surface and the floor, the numerical technique was employed to study the effects of the column layout (i.e., uniform, centralized, dispersed, and crossed distribution) on the air distribution of CAV mode in a standard four-column full scale model of a shopping mall. Seven indices, including airflow pattern, air diffusion performance index (ADPI), air temperature distribution, heat removal effectiveness, draught rate (DR), predicted mean vote (PMV), and carbon dioxide (CO₂) concentration, were used to assess the ventilation performance. In the CAV mode with a uniform column layout scheme, the experimental results indicated that the air supply flows downward along the wall surface, forming a secondary attachment with the ground and spreading along the floor in a fan radiation flow mode. Further, an "air lake" —like speed and temperature distribution similar to displacement ventilation (DV) was formed in the occupied zone. In all simulation cases, it was found that the average air velocity was less than 0.25 m/s in occupied zone, the effectiveness for heat removal was more significant than 1.0, DR value was less than 20%, the PMV level can also satisfy most people. The average CO₂ concentration was around 470 ppm in the occupied breathing zone. These results indicated that the CAV mode could be an efficient air distribution method. They demonstrated the technical feasibility of applying the CAV in the space under different column layout schemes.