中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
近年來玻璃隔熱膜科技逐漸成熟，應用之隔熱原理亦多元。玻璃隔熱膜由於施工簡易且由於無須施工鷹架等假設工程，尤其便於應用在針對既有建築之外殼玻璃之隔熱改善上。過去之研究顯示，在未考量隔熱性能之耐久性下，玻璃隔熱膜確實對減少室內之日射熱得有正面助益。然而，對比於傳統外遮陽版，隔熱膜之隔熱性能會隨時間劣化之情形將影響建築之應用與未來建築實際之節能效果，其節能上的性能劣化情形是建築使用者、建築設計者與產品生產者共同所關心的重要因子。目前業界對於隔熱膜所稱之保固，僅包括隔熱膜本身之物理性劣化，如產生氣泡、隔熱膜變色、脫膠等，對於隔熱性能上之劣化衰減也因為國內目前無相關性能衰減試驗規範，而無從評斷產品之耐久性。本研究之目的在於透過國內外相關文獻之回顧評析，建立建築玻璃用隔熱膜之隔熱性能衰減試驗方式，提供研訂相關標準草案之參考，以量化隔熱膜之性能劣化情形，將有助於建築設計者選用參考，並引導隔熱膜廠商研發高性能與耐久化之產品。
二、研究方法及過程
由於國際上目前尚無針對建築玻璃隔熱膜之性能衰減測試標準，而僅有耐候性測試之規範，其目的與本研究所欲探討光學性能上之衰減不同。為建立隔熱膜光學性能衰減之標準，因此本研究首先蒐集國內外有關材料或塗料類建材之標準性能劣化方式標準、規範或文獻，以探討並歸納國際上通用之性能劣化方式，以為本研究研訂草擬CNS「隔熱膜性能衰減試驗方法」草案之基礎。有鑑於擬定之標準試驗應能有效測得市售隔熱膜之性能隨時間衰減之程度，在國內外無相關文獻探討隔熱膜之性能衰減率下，本研究需事先進行前測試驗，以確定隔熱膜在加速劣化下其性能隨時間衰減之程度，藉以研訂標準測試之時間。因此，本研究借重內政部建築研究所性能實驗室，進行二種主要隔熱膜類型之加速劣化試驗，以及劣化前後隔熱膜光學性能測試，據以針對隔熱膜進行加速劣化時訂定合理之加速劣化光照暴露時間。
三、重要發現
1.完成國內外有關材料劣化試驗方法以及試驗儀器之相關規範回顧蒐集彙整分析。綜觀國內外文獻，目前未見針對玻璃隔熱膜之光學性能劣化之專門規範或標準，大多是針對耐候性之測試之標準。其中比較接近本研究目的者為歐盟與德國之DIN BS EN15752-1以及日本JIS A5759，本研究據此訂定我國之CNS草案。
2.完成挑選反射式與吸熱式等二大分類之隔熱膜共1800小時之加速劣化試驗。結果發現，不論是反射式或吸熱式之隔熱膜在劣化1800小時後，對於日光輻射取得係數(SHGC)性能之衰減是比較顯著的，分別有11.0%與9.7%之衰減情形。而可見光波段之透過率與反射率以及日光波段之反射率則無顯著之變化。
3.依據國內外文獻回顧與加速劣化之前測實驗數據，確立我國可行之建築玻璃隔熱膜性能劣化方式、使用之設備機器以及劣化操作循環之標準。
4.完成研擬CNS「建築玻璃隔熱膜光學性能衰減試驗方法」之草案內容。確立以加速劣化試驗機並使用UVA-340紫外線螢光燈管連續照射三個階段之劣化實驗。
5.建立並完成加速劣化時間與等效自然劣化時間之換算方法。
四、主要建議事項
根據本研究成果發現，提出下列具體建議：
建議一
建議轉送本研究成果之產出：「建築玻璃隔熱膜光學性能衰減試驗方法」草案予經濟部標準檢驗局訂定相關CNS標準之參考，以推廣綠建築在採用隔熱膜作為節能改善技術之應用：立即可行建議。
主辦機關：內政部建築研究所
協辦機關：經濟部標準檢驗局

1.Introduction
The technology of thermal insulation glazing films are maturely developed in recent years. The thermal insulation mechanisms of commercial glazing films are diversified. For the reason that the construction of glazing films is relatively simple and do not need scaffoldings, it is especially suitable for insulation upgrade of the fenestration of an existing building case. A previous research has showed that the glazing films are capable of reducing indoor solar radiation heat gains regardless of the films’durability. However, the performance degradation of films, especially for the optical performance, is the primary concern factor for application decision by architects, building investors, or film production companies in perspective of building energy conservation. The scope of the warranty of commercially available glazing film given by the production industry only includes its physical degradations, such as discoloring, losing adhesive capability, or appearing alveoli. There are no existing standards or regulations on how to adequately conduct a degradation experiment for the optical degradation of glazing films. The objective of this study is to propose a draft standard of the test method on the degradation of optical properties of adhesive films for building glass by literature reviews and pilot accelerated degradation experiments. The proposed test method provides a standardized optical performance accelerated degradation method for the application of identifying the commercial films’ performance degradation curve.
2.Methodology
As there are no existing international standards or regulations of the optical performance degradation test method. Most of these standards are focused on the weather durability testing, which is not sufficiently coincide with the aim of this study. Therefore, an extensive literature reviews were conducted regarding the artificial weathering methods of a variety related materials as fundamental references for formulating the standards of the testing method on the degradation of optical properties of adhesive films for building glass. In view of it lacks definitions on how much degradation exposure time is needed for optical performance degradation test; we planned and conducted a preliminary artificial degradation study. Two major types of the commercially available glazing films were tested using the accelerated weathering/degradation equipment for 1800 hours to understand their sensitivity between the exposure intensity and exposure time. This pilot study is conducted in the national building material testing laboratory.
3.Major findings
（1）Literature reviews of international standards on the testing method for material degradation is conducted. It is found that no existing standards are exclusively for glazing film’s optical degradation, most of them are for weathering test. The German standard, DIN BS EN15752-1, and the Japanese standard, JIS A5759, are the standards exclusively for building glazing films but still is focused on the weathering test.
（2）In this study, both solar reflective and absorptive type films were tested using accelerated degradation machine for study the effect of their optical properties degradation against exposure time due by UV light exposure. After 1800 hours testing, we observed that there is circa 11.0% and 9.7% decrease in the solar heat gain coefficient (SHGC). In contrast, there is no evident degradation in the reflectivity and transmissivity of the visible light as well as the reflectivity of the solar radiation.
（3）By referencing to the existing international and domestic standards, the degradation method, specification of the testing equipment, and the standardize degradation procedure were established.
（4）A standard for the testing method on the degradation of optical properties of adhesive films for building glass was drafted. The content includes using UVA-340 ultraviolet light as the lighting exposure source to a three steps’ degradation procedure utilizing accelerated degradation machine.
（5）A conversion method of the equivalent exposure time between the natural and artificial degradation was proposed in this study.
4.Recommendations
Base on this research an immediately feasible recommendation is reached: The major results of this project is drafting a standard draft of the testing method on the degradation of optical properties of adhesive films for building glass based on the findings of the degradation experiment. To promote the utilization and application of glazing films on existing buildings as a means of green building renovation, it is suggested to deliver this draft standard to the Bureau of Standards, Metrology and Inspection, Ministry of the Economic Affairs, for further consideration of formulating a formal CNS standard.