## 1 Introduction  
During the past 50 years, tropical island building construction in the South China Sea has been faced with two problems: Extremely scarce conventional building materials and very difficult energy supply. Nowadays, China is energetically advocating the strategy of land-sea integration and promoting ocean territory construction. Thus, studying building energy conservation in tropical island regions is urgently imperative [1; 2; 3]. However, on the one hand, compared with the Chinese inland area, the climate in the tropical island region situated in the South China Sea is exceedingly different, reflected in high temperatures, high humidity, intense radiation, high wind speeds, and strong rainfall etc. On the other hand, the current energy efficiency design standard performed in China is aimed at inland climates. Therefore, some design parameters in the current standard are not applicable for tropical island regions. Heat transfer coefficients of building external surfaces play a vitally important role in estimating building thermal load accurately, and some research has shown that the predicted energy loss might change from 20% to 40% depending on different values of the convective heat transfer coefficient (CHTC) in the literature [4], and a 15% uncertainty in CHTC can bring about a corresponding 15%-20% uncertainty of heat flow through building envelope [5]. However, the current national code [6] has certain limitations on the regulation of heat transfer coefficients. Firstly, the total heat transfer coefficient (THTC) of a building external surface is stipulated as a constant, for example, 23.0 W/(m\({}^{2}\cdot\)K) in winter and 19.0 W/(m\({}^{2}\cdot\)K) in summer. Secondly, the THTC only includes two parts: CHTC and radiation heat transfer coefficient (RHTC). Envelope surfaces are assumed to be dry all the time and the evaporative heat transfer coefficient of a building external surface (EHTC) is ignored. Based on the analysis above, it is extremely necessary to survey the reasonable values of heat transfer coefficients, making up for the lack of surface heat transfer coefficients in energy conservation design of tropical island buildings. In the past work, a large number of studies aimed at determining more reliable CHTCs have been performed, owing to the complexity of convective heat transfer. One of the earliest experimental investigations on CHTC was that of [PERSON], and this work was conducted in a wind tunnel. Finally, CHTC was expressed as a linear relation or exponential form of wind speed, which is still cited by many references widely [7]. Similarly, [PERSON] [8], [PERSON] [9], and [PERSON] [10] also measured CHTCs on a structure surface in a wind tunnel laboratory. However, although experimental conditions in a wind tunnel could be controlled easily, it cannot produce a real enough outdoor environment [11; 12], bringing about deviation for experimental results. Hence, it is a better choice to conduct full-scale measurements, and a large number of full-scale measurements on CHTC have been conducted in the past studies. [PERSON] et al. [13] investigated the influences of solar radiation, wind speed, and temperature difference between wall surfaces and ambient air on CHTC, and found that CHTC would not follow the variation mode of solar radiation and temperature differences, but was directly related to wind speed. [PERSON] et al. [14] tested the CHTCs of slanting housetops by heating plates in natural environments, and linked wind speeds and CHTCs on the windward or leeward sides. [PERSON] and [PERSON] [15; 16] performed lots of outdoor experiments by the heat balance method and gave the correlation between wind velocity and CHTC, which considered the turbulent effect. [PERSON] and [PERSON] [17] measured the CHTC on the surface of a low-storied building in shelter circumstances, and obtained various relational expressions between CHTCs and wind speeds. Furthermore, some similar full-scale measurements were performed in other studies [18; 19; 20; 21; 22].