不同木質牆體結構設計對其溫度與含水率的影響

Abstract

木構造建築易建造，成本低，但木建築處於如台灣高溫多濕的氣候中，溼氣易在壁體內累積，造成木材腐朽、發霉或遭白蟻危害的情形，人長期居住在內部大量累積濕氣的環境內甚至容易產生病態屋症候群（Sick building syndrome, SBS），而耐久性的研究著重在環境上的溫濕監測，過去有許多學者做過相關的研究，即發現外在環境變化會從耐久性的角度對結構造成影響。 本實驗設計上使用3組壁體（A、B、C），配置上屬東西向，做2重複性的試驗（壁體本身又分為上下半部，代號上標記為EA-U，E = East，U = Up；EA-D，D = Down等，以此類推），三種壁體在內部組成結構皆不相同，藉由整合壁體內溫溼度監測與含水率測量之數據做分析，分析結果主要分為兩部分，一部分是仿效前人研究，從壁體內的溫溼度分析資料，從各壁體的溫度日均變化比較，東側表現上下半部有一致性，西側表現則上下半部各自有不同的排序，從溫度變動比的統計來分析壁體阻隔熱量流入的差異，C類型壁體整體上變動比超過1的天數最少，且在這些天數裡的日較差平均值也最低，代表C是三種壁體中較能保持熱量不流失，溫度變化較穩定的，壁體內相對濕度按同樣方式分析，壁體內相對濕度的日均變化無論在東西側都是上下半部有各自的一致性，從相關性的分析結果可以看出，室外相對濕度與壁體內相對濕度的相關性並不高，在變動比分析上也證實了變動比超過1主要是受室外相對溼度的影響，且各壁體間差異不大。 本研究重點探討在第二部份的含水率變化延遲效果，以EC壁體的數據定出分析流程，接著比較EC與WC壁體的效果，兩壁體延遲效果並沒有特別明顯的差異，且內部組成完全相同，雖有間接的證據能說明WC壁體內水分傳送的速度較緩慢，但仍無法直接說明哪一個方位的C類型壁體效果較佳，最後一部分是比較西側三個壁體的延遲效果，WA與WC在組成上只有防潮材的差異，在兩區段（即相對濕度影響OSB板含水率與OSB板影響花旗松含水率）間的延遲效果上，WA較WC壁體皆多延遲了30分鐘，顯示出使用活性碳防潮布可以有略優於使用油毛氈作為防潮材的效果，WB壁體在延遲效果上則低於WA與WC壁體，兩壁體間的組成只差在25 mm的隔熱板，證實厚度也影響水分傳送的速度，分析檢討的結果最後以WA壁體表現最優，WC次之，WB是表現最差的一組。

Owing to easy construction and low cost, the wood frame structure house has been the main product of North America style in Taiwan. However, the hot and humid climate is totally different from that in North America. The wall structure of wood frame house is needed to be improved and modified in order to avoid moisture accumulation or leakage that will cause wood decay, moldy, or attacked by termites. Sometimes even cause the “Sick building syndrome”. So the durability of the wood building, especially in wall has become a popular subject. As many scholars have done related research, which found that changes in external environment from the perspective of the durability will affect the structure. This research plan using 3 types of walls（A、B and C）. The configurations are east-west direction. Doing the two repeats test.（Every wall can be parted with upper side and lower side. Using symbols like EA-U, EA-D, etc. That “EA-U” means the data of the upper side east A type wall.） By the combination of the hygrothermal and moisture content data to analysis. The analytical result has two parts. The first part is analyzing the temperature and relative humidity data inside the wall. It showed more obvious in discrepancy by doing the statistics of the temperature differential ratio（TDR）. In experiment period, C type had the fewest days which the TDR value above 1. And C type wall had the lowest average value of temperature differential per day between outdoor and inside the wall in these days. These result meant C type wall was more stable for containing heat inside than other two. Also the relative humidity part had been done the same analysis. In relative humidity variation section, it seemed not much relativity between the relative humidity value of outdoor and inside the walls from the correlation result. And the relative humidity differential ratio（RHR）displayed the major factor of RHR value over 1 was the outdoor RH value. Most of all, the number of days that RHR value over 1 were all the same in each group. The second part of this research was the moisture content （MC） time delay effect in different types wall. The first step used EC wall to establish the analytical procedure. The next step was to compare EC wall and WC wall. But there were no significant difference in time delay effect, though there had the indirect proof to say the moisture transport speed was slower in WC wall. The final step was to compare the time delay effect of 3 type walls on west side. The only structural difference between WA and WC wall was the moisture resistance material. The result displayed that WA had about 30 minute longer than WC whether in “RH inside to OSB-MC” part or “OSB-MC to S-MC” part. The most important thing was that using activated carbon moisture-resistive membrane could has better performance than using rubberized asphalt. WB wall was the worst wall in time delay effect. Since the WB didn’t have 25 mm PS board, which WA and WC did. It showed that thickness could also affect the speed of moisture transportation. The total result showed WA wall performed the best in this research, WC is the second and WB is the worst.