Correlations in thermal comfort and natural wind

Abstract

Many 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 coefficient=0.56, p<0.001) 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].