Vacuum insulation panels (VIPs) with a glass-fiber core has been considered to be difficult to operate for a long period of time, such as for building applications, because the thermal conductivity rises rapidly as the pressure increases. However, glass-fiber-core VIPs contain a material called a getter that continuously adsorbs permeated gas, and a theoretical model that considers the properties of the getter has not yet been developed. In this paper, the gas-adsorption mechanism by getters was investigated and a long-term-performance prediction model that considers the temperature dependence was proposed. Some gases were not adsorbed by the getter in the VIPs; however, a model was proposed that takes into account the non-absorbed gases by applying partial pressure to the adsorption isotherm in advance. The long-term performance of VIPs with different areas and volumes was compared with the measured values, and the validity of the calculation results was confirmed. These results show that the long-term performance of VIPs of different sizes can be accurately predicted when the getter performance is well understood.

Indoor microbial communities play a critical role in influencing indoor environmental quality and human health and are shaped by occupant activity, surface characteristics, and environmental conditions. While previous studies have examined these factors individually, systematic evaluations of their combined interactions, particularly involving Heating, Ventilation, and Air Conditioning (HVAC) and drainage systems, remain limited. This controlled, long-term (1.5-year) investigation assessed how human occupancy, surface moisture (dry vs. wet), aquaponics (soilless plant-aquarium systems), and environmental parameters (humidity, ventilation, and seasonal variations) influence bacterial and eukaryotic dynamics in tightly sealed residential units. Continuous air-conditioner operation without fresh-air intake led to elevated CO₂ levels during occupancy and pronounced seasonal humidity fluctuations, emphasizing the need for improved ventilation and adaptive humidity control in compact urban residences. Amplicon sequencing revealed higher microbial diversity on dry surfaces (aerosols, air-conditioner filter dust, and floor dust) than on wet surfaces (waste drains and showerheads). Wet environments supported biofilm-associated taxa adapted to moist conditions (e.g., Methylobacterium, Vermamoeba). Human occupancy significantly enriched air-conditioner filter dust with opportunistic bacteria (e.g., Finegoldia and Streptococcus), underscoring occupant-driven microbial accumulation via recirculated air. Additionally, the small-scale aquaponic system had minimal measurable influence on microbial composition at the room scale, suggesting limited aerosolization or dispersal under typical usage conditions. Indoor relative humidity was significantly correlated with microbial diversity in air systems, notably enhancing moisture-adapted taxa such as Sphingomonas during humid seasons. Seasonal variations markedly influenced eukaryotic communities (e.g., pollen influx), whereas bacterial communities were more strongly influenced by human occupancy. These findings highlight the critical role of human-driven microbial accumulation in air-conditioner filters and the distinct microbial profiles associated with dry and wet indoor surfaces. Although small-scale aquaponics demonstrated minimal room-wide microbial impact, its potential localized influence warrants further exploration. These insights offer practical guidance for targeted hygiene protocols, HVAC system maintenance, and building design strategies aimed at improving indoor microbial quality and supporting occupant health.

In our living environment, there are various microorganisms that are thought to affect human health. It is expected that excessive microbial suppression can have a negative effect on human health and that the appropriate control of the microbiome is beneficial to health. To understand how the physical environment, such as temperature and relative humidity, or housing itself affects the microbiome in a rural house, we measured temperature and humidity and collected microbial samples in a traditional Japanese house with a thatched roof. The relative humidity of outdoor air was over 60% most of the day throughout the year. Indoor and outdoor air temperature and humidity were closer to each other in summer than in winter. The DNA concentration of indoor surfaces correlated with the relative humidity, especially with the lowest annual relative humidity. In the thatched roof, outside surface relative humidity often reached 100%, and the occurrence of condensation can affect the DNA concentrations. A high percentage of archaea were detected in the house, which is not a common characteristic in houses. In addition, the microbial community was similar outdoors and indoors or in each room. These characteristics reflect the occupants’ behaviour, including opening the windows and partitions in summer. In the future, it will be necessary to conduct continuous surveys in various houses, including traditional and modern houses, in Japan.

Mold growth poses a high risk to a large number of existing buildings and their users. Air leakage through the air cavities of the building walls, herein gaps between walls and air conditioner pipes penetrating the walls, may increase the risks of interstitial condensation, mold growth and other moisture-related problems. In order to quantify the mold growth risks due to air leakage through air cavity, an office room in a historical masonry building in Nanjing, China, was selected, and its indoor environment has been studied. Fungi colonization can be seen on the surface of air conditioner pipes in the interior side near air cavity of the wall. Hygrothermometers and thermocouples logged interior and exterior temperature and relative humidity from June 2018 to January 2020. The measured data show that in summer the outdoor humidity remained much higher than that of the room, while the temperature near the air cavity stays lower than those of the other parts in the room. Hot and humid outdoor air may condense on the cold wall surface near an air cavity. A two-dimensional hygrothermal simulation was made. Air leakage through the air cavities of walls proved to be a crucial factor for mold growth.