Failure to maintain thermal equilibrium can cause uncontrollable increases in body core temperature beyond critical upper limits. In selecting clothing, consideration must be given to the heat transfer properties of clothing that may restrict the cooling capacity of the human body under heat stress conditions, most importantly, apparent total evaporative resistance (Re,T,a). This study calculated and compared Re,T,a for five clothing ensembles under varying heat stress conditions, including three relative humidity (RH) levels and three stages of heat stress to determine if Re,T,a values varied or remained the same with changes in heat stress conditions. A four-way mixed model analysis of variance demonstrated significant differences for estimated Re,T,a values among ensembles, RH levels, heat stress stages, and interactions among ensembles and RH levels and ensembles and heat stress stages (p < 0.0001). No significant interaction among RH levels and heat stress stages was found (p = 0.67). A Tukey's Honestly Significant Difference multiple comparison test was used to identify where significant differences occurred (p < 0.05). The results of the study indicated that Re,T,a values do change with RH levels and stages of heat stress and that the theoretical framework for explaining heat-exchange in hot environments is not yet well-established. Also confirmed was the dominance of the convection pathway over the diffusion pathway in hot environments.

HotHumiBox är en försöksutrustning som finns på Linnéuniversitetet och som ska ge bättre kunskap och förståelse om hur fukt och temperatur varierar i en provkropp monterad mellan två kammare där klimatet kan styras var för sig. Syftet med examensarbetet är att undersöka om HotHumiBoxen fungerar väl och huruvida den kan börja användas i undervisningen i olika kurser inom institutionen för byggteknik på Linnéuniversitetet, bl.a. i samband med demonstrationslaborationer vid föreläsningar om fukt. För att genomföra arbetet har mätningar med tre olika klimat utförts på ett provelement som motsvarar en yttervägg som kan finnas i nybyggda typhus. Resultatet av mätningar utförda med HotHumiBoxen presenteras i form av tabeller och diagram och jämförs slutligen med beräkningar av fukt- och temperaturtillstånd. Jämförelsen mellan mätningar och beräkningar visar att givarna som styr klimatet i båda kamrarna visar mycket bra resultat. Däremot visar majoriteten av givarna i provelementet antingen lite för höga eller för låga värden för att resultatet ska anses som tillfredställande. För att få en bekräftelse på att HotHumiBoxen fungerar väl rekommenderas därför att ytterligare mätningar görs. / HotHumiBox is an experimental equipment that is available at Linnaeus University and is supposed to provide better knowledge and understanding about the way moisture and temperature varies in a building element installed between two chambers in which the climate can be controlled separately. The purpose of this work is to investigate whether the HotHumiBox works well and whether it can be used at various courses at the Department of Building Technology at Linnaeus University, such as demonstration laboratory experiments at lectures on moisture. Measurements with three different climates were performed on a building element that corresponds to a wall that could be installed in modern houses. The results of the HotHumiBox measurements are being presented in tables and diagrams and are being compared with moisture and temperature calculations. The comparison between measurements and calculations shows that the sensors which control the climate in both chambers show very good results. On the other hand, the majority of the sensors in the test element show either too high or too low values for the result to be considered as satisfactory. Therefore, it is recommended that some more tests and measurements are done before it can be concluded that the HotHumiBox work well.