Among the various energy-efficient building technologies that have been developed through an completed RGC CRF project under the leadership of Prof. Christopher Chao, passive radiative cooler and smart window are the two innovative and promising technologies, which are especially ripe for introducing to industries.

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Passive radiative cooler is a wall panel for building façade to provide cooling effect for indoor environments by radiative cooling. Radiative cooling is a process of heat removal from a sky-facing surface to the universe. It is a passive way requiring no additional energy input like electricity.

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Smart window responses to external stimulus such as voltage (electrochromic), heat (thermochromic) and light (photochromic). These windows regulate their characteristics in terms of optical and thermal properties. Thermochromic smart window blocks solar radiation at high temperature or allow incoming radiation in during cold weather to maintain indoor thermal comfort.

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The potential of these technologies in energy saving for buildings has been proven by different thermal analysis like field experiment and energy simulation software. Installation of passive radiative cooler and thermochromic smart window can reduce solar heat gain and HVAC energy consumption and more importantly, they require no electricity and are environmental-friendly.

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一個由趙汝恆教授領導的RGC CRF項目研發了各種各樣的節能建築技術。被動式無源輻射冷卻器和智能窗戶是其中兩種創新而又成熟的技術，能夠將其引入行業。

 

被動式輻射冷卻器是一種用於建築外墻的墻板，通過輻射冷卻為室内環境提供冷卻效果。輻射冷卻是將熱量從面向太空的表面釋放到宇宙的過程。這種被動的方式無需額外的能量，如電力。

 

當智能窗戶受到如電壓(電致變色)、熱量/溫度(熱致變色)以及光(光致變色)等外部刺激時，這些窗戶會調節自身光學和熱學的特性。在高溫的情況下，熱致變色智能窗戶會阻擋太陽輻射或在處於寒冷天氣的時候，讓太陽輻射進入室内，以保持舒適的室内環境。

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各種如實地實驗和能源模擬軟件等熱分析證明了這些技術在建築節能方面深厚的潛力。安裝被動式無源輻射冷卻器和熱致變色智能窗戶能夠減少建築吸收的太陽熱量和HVAC的能源消耗，更重要的是他們無需用電并且對環境友好。