Correlations in thermal comfort and natural wind

Abstract

a b s t r a c tMany field surveys have shown that naturally ventilated buildings are favorable to human thermal comfort and may allow higher cooling temperatures than air-conditioned buildings. Recreating natural wind characteristics with a mechanical cooling system may diminish the drawbacks of conventional cooling systems such as drafts and high energy demands.Natural wind characteristics (wind velocity, direction, turbulent intensity, temperature and relative humidity) were recorded in a mountain environment and correlated with the human thermal sensation of 48 subjects. Natural wind fluctuation characteristics were analyzed using the Fast Fourier Transform (FFT) analysis. The dynamic characteristics of natural wind were averaged through the power spectrum exponent (β−value), which represents the energy distribution of the turbulent flow of natural wind. The power spectrum exponent (β−value) of the natural wind will decrease when the mean velocity increases, while it will increase when the turbulent intensity increases. The power spectrum exponent (β−value) was correlated (Spearman's rank coefficient¼ 0.56, po0.001) with thermal comfort. The power spectrum exponent (β-value) for people feeling comfortable has a median value of 1.62 [1.41-1.80 for the first and third quartiles, respectively] and the β−value for people feeling uncomfortable has a median value of 1.10 [0.97-1.25].

The scope of inducing natural air supply via the façade

“…The optimum range for β-values is between 1.41 and 1.80 and are mainly found in natural airflows (Kang, Song, and Shiavon 2013). This supports the findings that people prefer airflows from systems with the characteristics of those found with natural ventilation.…”

“…The higher the value, the higher the power in the low frequencies, which represents large period eddies (Ouyang 2006 gives examples of β-values of natural and mechanical airflows (Kang, Song, and Shiavon 2013). When we take a closer look at the difference in spectrum characteristics between natural and mechanical airflows, we see that natural airflows have higher β-value than mechanical ones.…”

Analysis of Resilient Design by Thermoacoustic Adaptation of Tropical Urban Model

“…While Kang et al (2013) explained the highest frequency of thermal comfort that was obtained for specific wind speed, this study recommends the ventilation strategy represented by WWR. Designing the thermal control could not ignore the acoustical factor.…”

Outdoor Thermal Comfort in a Transitional Space of Canopy in Schools in the UK

“…However, these temperatures are directly influenced by the integrated effect of all the above climatic parameters, which interact with and affect each other. Therefore, in a sunny winter environment with little wind, the mean radiant temperature is just as important as the air temperature, and its significance increases in the summer [33]. In Mediterranean countries, MRT easily reaches 60-70 • C with air temperatures of about 30-35 • C. In windy environments, air temperature becomes more important than radiant temperature because convective heat exchange dominates [34].…”