Background: Bacteria are readily nourished in airtight environments with high humidity, such as storage cabinets, clothing closets, and corners, where ventilation is normally low and humidity is high. Objectives: We characterized the role of humidity and ventilation in bacterial growth and genus distribution at different temperatures (26 °C and 34 °C). Methods: Fresh pork, which was used as the substrate for bacterial culture, was placed in storage cabinets. Bacterial growth and genera distribution on the surface of pork placed in a storage cabinet under different temperatures (26 °C and 34 °C); relative humidity levels (RH: 50%, 70%, 90%); and ventilation conditions (no ventilation and low, medium, and high levels of ventilation) were assessed by rDNA sequencing. Results: Increased ventilation and reduced humidity significantly decreased bacterial growth at 26 °C and 34 °C. The contribution of increased ventilation to the reduction in bacterial growth exceeded that of decreased humidity. Ventilation had the greatest effect on reducing bacterial growth compared to the unventilated conditions at 70% RH. At 34 °C, medium and high levels of ventilation were required to reduce bacterial growth. High temperatures greatly increased bacterial growth, but ventilation could reduce the degree of this increase.

Air temperature thresholds are investigated and proposed for acceptable comfort in air-conditioned buildings. Using the ASHRAE database of field studies in which acceptability votes were obtained from occupants, it is shown that within the thresholds the acceptability is indistinguishable. Therefore, there is little gain from conditioning spaces to an ‘optimum’ air temperature, a practice that involves significant energy cost. However, beyond the thresholds there is a significant drop-off in acceptability. Ideally, air-conditioning would be used only when the environmental conditions are beyond the thresholds. The use of ceiling fans or personal environmental control systems broadens the threshold range. Thresholds are determined for both air-conditioned and ventilation-cooled buildings in the database. The equally acceptable range between the thresholds is 8–10 K in both types of buildings. It is possible that a perception of reduced air quality in warm environments could impose an upper temperature threshold. Perceived air quality is examined in two laboratory studies with air temperatures ranging from 18 to 30°C. Perceived air quality is seen to be closely correlated to thermal comfort rather than to temperature; as long as thermal comfort is maintained by air movement, perceived air quality will be acceptable. Relationships between temperature thresholds and productivity, operating set-points, and energy use are also discussed. Les seuils de température de l'air sont étudiés et proposés pour un confort acceptable dans les immeubles climatisés. En utilisant les études de terrain figurant dans la base de données de la Société américaine des Ingénieurs en Chauffage, Réfrigération et Climatisation (ASHRAE), dans lesquelles il a été obtenu de la part des occupants des réponses relatives à l'acceptabilité, il est montré que, dans la limite des seuils, l'acceptabilité n'est pas discernable. Il y a par conséquent peu de bénéfice à climatiser des espaces à une température « optimale » de l'air ce qui êntraine des frais significatifs. Cependant, au-delà des seuils, l'on constate une baisse sensible de l'acceptabilité. Dans l'idéal, la climatisation ne serait utilisée que lorsque les conditions environnementales dépassent les seuils. L'utilisation de ventilateurs de plafond ou de systèmes de contrôle individuel de l'environnement élargit la plage des seuils. Les seuils sont définis à la fois pour les immeubles climatisés et les immeubles refroidis par ventilation figurant dans la base de données. La plage offrant une égale acceptabilité entre les seuils se situe à 8-10 K dans les deux types d'immeubles. Il est possible que la perception d'une réduction de la qualité de l'air dans des environnements chauds puisse imposer un seuil de température supérieur. La qualité de l'air perçue est examinée dans deux études de laboratoire pour des températures de l'air allant de 18 °C à 30 °C. Il apparaît que la qualité de l'air perçue est étroitement corrélée au confort thermique plutôt qu'à la température; tant que le confort thermique est maintenu par la circulation d'air, la qualité de l'air perçue sera acceptable. Il est également discuté des relations entre les seuils de température et la productivité, les points de consigne et l'utilisation de l'énergie. Mots clés: confort adaptatif circulation d'air immeubles climatisés fonctionnement libre contrôle individuel de l'environnement (CIE) acceptabilité thermique confort thermique

Thermal comfort is one of the primary factors influencing occupant health, well-being, and productivity in buildings. Existing thermal comfort systems require occupants to frequently communicate their comfort vote via a survey which is impractical as a long-term solution. Here, we present a novel thermal infrared-fused computer vision sensing method to capture thermoregulation performance in a non-intrusive and non-invasive manner. In this method, we align thermal and visible images, detect facial segments (i.e., nose, eyes, face boundary), and accordingly read the temperatures from the appropriate coordinates in the thermal image. We focus on the human face since it is often clearly visible to cameras and is not merged into a hot background (unlike hands). We use a regularized Gaussian Mixture model to track the thermoregulation changes over time and apply a heuristic algorithm to extract hot and cold indices. We present a personalized and a generalized comfort modeling method, selected based on the availability of the occupant historical indices measurements in a neutral environment, and use the time-series of the hot and cold indices to define corrections to HVAC system operations in the form of setpoint constraints. To evaluate the efficacy of our proposed approach in responding to thermal stimuli, we designed a series of controlled experiments to simulate exposure to cold and hot environments. While applying personalized modeling showed an acceptable average accuracy of 91.3%, the generalized model’s average accuracy was only 65.2%. This shows the importance of having access to physiological records in modeling and assessing comfort. We also found that individual differences should be considered in selecting the cooling and heating rates when some knowledge of the occupant’s overall thermal preference is available.