Flux profile method를 이용한 옥상녹화의 에너지 수지 분석

다국어 초록 (Multilingual Abstract)

This study experimentally investigated the thermal effects of green roofs, a green infrastructure practice for mitigating the urban heat island effect and building thermal loads, from the perspective of the surface energy balance. Four independent test buildings of identical dimensions — a bare concrete roof, a high-reflective paint roof, and two green roofs planted with stonecrop and grass — were constructed in an open field, and long-term field observations were conducted from April 2021 to December 2022, covering 584 effective observation days. For six analysis periods representing distinct seasonal and rainfall conditions, the surface energy balance of each roof was estimated using the Flux Profile Method （FPM） based on temperature and humidity gradients observed at two heights, and the estimates were validated against independent observations from four-component net radiometers （CNR4）.
The observations showed that during the rainless summer period, the green roofs lowered the maximum roof surface temperature by up to 24.0–24.5℃ compared with the bare concrete roof （maximum 55.3℃） and reduced the maximum indoor temperature by 7.9–8.0℃, while in winter they kept the minimum indoor temperature 2.6–3.1℃ higher. The energy balance analysis demonstrated that these temperature differences originate from the distinct energy partitioning structures of the roof surfaces. During the rainless summer period, the daytime mean latent heat flux of the green roofs reached 162.5–198.0 W/m², accounting for up to 77.8% of the net radiation, whereas the ground heat flux was the dominant component for the bare concrete roof. The ground heat flux of the stonecrop roof was only about 5% of that of the concrete roof, indicating that the soil–vegetation layer blocked approximately 95% of the heat flow toward the building, and the latent heat flux corresponded to an evapotranspiration rate of 3.0–3.2 mm/day. A comparison of the energy partitioning under different rainfall conditions revealed that the green roofs maintained an evaporation-dominated structure with latent heat fractions of 56.4–77.8% under soil-water depletion, replenishment, and saturation conditions alike, whereas evaporation from the impervious surface was a transient phenomenon limited to the period immediately after rainfall — demonstrating that energy partitioning is governed primarily by the surface type rather than by individual rainfall events. In winter, all fluxes of the green roofs decreased below 15 W/m², showing that the soil–vegetation layer acts as an insulating layer. The applicability assessment of the FPM yielded NSE values of 0.624–0.850 （satisfactory to very good） for the raw data during the growing seasons, and 20 of the 24 cases reached the good grade or higher based on the 120-minute moving average, confirming the applicability of the method to small-scale roof surfaces.
These results provide energy-balance-based evidence that the cooling effect of green roofs in summer originates from the redistribution of energy through evapotranspiration and that their insulation effect in winter results from the heat-blocking function of the soil layer. The findings offer a hydrometeorological basis for green roofs as a green infrastructure that simultaneously improves the urban thermal environment and water cycle, and demonstrate that the FPM, requiring only low-cost gradient observations, can serve as a practical tool for the quantitative assessment of small-scale green roof systems.

목차 (Table of Contents)

• 제 1 장 서론 1
• 1.1 연구의 배경 1
• 1.2 연구의 필요성 4
• 1.3 연구의 목적 6
• 1.4 연구의 기대효과 7
• 1.5 문헌조사 8
• 1.6 기존연구의 한계 및 본 연구의 차별성 12
• 제 2 장 연구동향 13
• 2.1 이론적 배경 및 선행연구 고찰 13
• 2.2 옥상 피복 및 식생 유형에 따른 특성 비교 17
• 제 3 장 방법론 19
• 3.1 실험준비 및 모의실험동 제원 19
• 3.2 관측 장비 설치 25
• 3.3 모의실험동 동질성 평가(Homogeneity Evaluation) 31
• 3.4 Flux Profile Method 38
• 제 4 장 관측자료 분석 44
• 4.1 봄 관측자료 분석 48
• 4.2 여름 관측자료 분석 58
• 4.3 가을 관측자료 분석 85
• 4.4 겨울 관측자료 분석 94
• 제 5 장 Flux Profile Method 적용 및 결과분석 104
• 5.1 봄 분석기간 105
• 5.2 여름(무강우) 분석기간 115
• 5.3 여름(간헐적 강우) 분석기간 125
• 5.4 여름(집중호우) 분석기간 135
• 5.5 가을 분석기간 145
• 5.6 겨울 분석기간 155
• 5.7 여름철 강우 조건별 표면 에너지 수지 분배율 비교 165
• 5.8 Flux Profile Method 적용성 검증 170
• 제 6 장 결론 및 고찰 176
• 6.1 결론 176
• 6.2 고찰 178
• 참 고 문 헌 179
• Abstract 185