| Abstract: | 近年來都市綠化興起以可食地景打造田園城市風潮，都市地狹人稠寸土寸金，屋頂運用成可食地景，栽種蔬菜不僅可食，是否亦具有降溫節能之效果，國內尚未見相關研究。因此本研究選擇可食蔬菜為研究對象，探討可食地景於屋頂樓板降溫之效果，建立屋頂可食地景綠化且具降溫之選種原則，推廣予大眾應用。採試驗方式進行研究，時間自104年5月29日至7月26日，地點位於彰化市一棟2層樓建築物平面屋頂。選擇10種蔬菜，包括：小白菜、角菜、芥藍菜、青梗白菜、紅鳳菜、韭菜、落葵、福山萵苣、蔥、蕹菜。採用模矩型植生盆器，介質為燒結污泥混合泥炭土，深度10公分。容器、介質、液肥及維護管理等均相同，僅日照不同（全日照及網罩），各重複2盆。選擇中午（13：00～14：00）進行調查，項目包括：綠覆率、株高、樓板溫度及盆器底部溫度。調查結果發現平均降溫（樓板溫度與盆器底部溫差）於日照組達21.15°C，網罩組雖僅為13.54°C，但網罩組之樓板、以及盆器底部溫度均較日照組為低；樓板平均溫度於網罩組較日照組低8.80°C，網罩組之盆器底部溫度較日照組低1.18°C。不論日照組或網罩組，均以蕹菜之平均降溫為最高，分別達23.77°C以及15.79°C，其次為紅鳳菜之23.22°C與15.53°C。本研究另研擬屋頂降溫之3項影響因子，包括：株高、綠覆率、高度覆蓋度指數。採用Pearson相關分析，探討各蔬菜降溫因子與降溫之關係，發現株高不具相關性，綠覆率、高度覆蓋度指數均具顯著相關，亦即綠覆率及高度覆蓋度指數越高時、降溫程度亦越多。迴歸分析發現降溫預測模式（Y）均納入株高（X1）、高度覆蓋度指數（X3），綠覆率（X2）部分沒有納入。此預測模式，說明屋頂種植蔬菜選擇株高越高、綠覆率越高者，對於降溫亦越多。本研究證實屋頂採用蔬菜之可食地景，於夏季高熱時具有明顯降溫效果，具高綠覆率之蔬菜降溫效果較佳，另外，建議增設網罩，不僅降溫較多，且兼具蔬菜防蟲害之效果。
The urban greening rises in recent years, the garden city is built by edible landscape, the limited urban area has dense population, the rooftop is used as edible landscape, the planted vegetables are edible, and they are effective on cooling and energy saving. There is no related study in Taiwan. Therefore, this study selects edible vegetables as research subject, discussing the effect of edible landscape on cooling the rooftop slab. Establish plants selection criterion of edible landscape on the rooftop, to promote the public use.The test period was May 29 to July 26, 2015; the site was the flat roof of a two-story building in Changhua City. Ten vegetables were selected, including Brassica chinensis, Artemisia lactiflora, Brassica oleracea var. acephala, Brassica chinensis cv. Ching-Geeng, Gynura bicolor, Allium tuberosum, Basella alba, Lactuca sativa, Allium fistulosum, Ipomoea aquatica. The molded rectangular vegetation basin was used, the medium was sintered sludge mixed with peat soil, 10 cm deep. The container, medium, liquid fertilizer and maintenance management were identical, only the sunshine was different（full sun and mesh enclosure）, repeated two basins. The investigation was conducted at noon（13:00～14:00）, the items were green coverage rate, plant height, floor slab temperature and basin bottom temperature. The findings show that the average cooling（difference between floor slab temperature and basin bottom temperature）of sunshine group is 21.15℃, that of mesh enclosure group is only 13.54℃, but the floor slab and basin bottom temperatures of mesh enclosure group are lower than the sunshine group. The average floor slab temperature of mesh enclosure group is lower than sunshine group by 8.80℃, the basin bottom temperature of mesh enclosure group is lower than sunshine group by 1.18℃. The Ipomoea aquatica has the maximum average cooling in sunshine group or mesh enclosure group, which is 23.77℃ and 15.79℃ respectively, and then 23.22℃ and 15.53℃ of Gynura bicolor. This study plans three vegetable cooling effect factors influencing the rooftop thermal reduction, including plant height, green coverage rate and height coverage index. Pearson correlation analysis is used to discuss the relationship between vegetable cooling effect factors and cooling degree. The findings show that the plant height is uncorrelated, the green coverage rate and height coverage index have significant correlation. Namely, the higher the green coverage rate and height coverage index are, the higher is the cooling degree. Regression analysis found that cooling prediction mode（Y）are included in height（X1）, height coverage index（X3）, green cover rate（X2）section was not included. This prediction mode shows that select the higher plant height and coverage rate have higher cooling degree.This study proves that the edible landscape of vegetables on the rooftop has apparent cooling effect in summer; the vegetables with high green coverage rate have better cooling effect. In addition, the mesh enclosure is recommended, not only reducing the thermal a lot, but also protecting the vegetables against insects. |
