• 한국환경복원기술학회지
• /
• 제15권2호
• /
• pp.137-147
• /
• 2012

GRS is an effective urban ecology restoration technique that can manage a variety of environmental functions such as ecological restoration, rainwater spill control and island heat effect from a low-impact development standpoint that can be utilized in new construction and retrofits. Recently, quantitative evaluation studies, both domestic and abroad, in the areas related to these functions, including near-earth surface climate phenomenon, heavy rainwater regulation, thermal environment of buildings, have been actively underway, and there is a trend to standardize in the form of technological standards. In particular, centered on the advanced European countries, studies of standardizing the specific insulation capability of buildings with green system that comprehensively includes the green roof, from the perspective of replacing the exterior materials of existing buildings, are in progress. The limitation of related studies in the difficulties associated with deriving results that reflect material characteristics of continuously evolving systems due in part to not having sufficiently considered the main components of green system, mechanisms of vegetation, soils. This study attempts to derive, through EnergyPlus, the effects that the vegetation-related indicators such as vegetation height, FCV, etc. have on building energy load, by interpreting vegetation and soil mechanisms through plant canopy model and using an ecological standard indicator LAI that represent the condition of plant growth. Through this, the interpretations that assume green roof system as simple heat insulation will be complemented and a more practical building energy performance evaluation method that reflects numerical methods for heat fluxes phenomena that occur between ecology restoration systems comprised of plants and soil and the ambient space.

• 한국환경과학회지
• /
• 제19권7호
• /
• pp.843-848
• /
• 2010

This study focused on the characteristics of change soil water with respect to soil thickness and soil mixture ratio, in order to effectively carry out an afforestation system for a roof with a low level of management and a light weight. Soil hardness tended to increase as sand particle was increase regardless soil thickness and soil porosity had more higher artificial soil than natural soil mixture. In case of soil pH, natural soil mixture had between 6.7 and 7.4, and artificial soil mixture had 6.0~6.8. Organic matter, electrical conductance and exchangeable content were highest in $L_{10}$, which it had the highest leafmold ratio. Soil moisture tension(kPa) in 15cm soil thickness was observed natural soil mixture had a considerable change but artificial soil mixture had a gradual change when non-rainfall kept on. In the experimental $L_{10}$, $S_{10}$, $S_7L_3$ and $S_5L_5$ object, the amount of moisture tended to rapidly decrease. However, in the experimental $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$ and $P_4P_4L_2$ objects, which contained pearlite and peat moss, the amount of moisture tended to gradually decrease. As a result, the use of a artificial soil mixture soil seems to be required for the afforestation of a roof for a low level of management.

• 한국생활환경학회지
• /
• 제21권6호
• /
• pp.959-964
• /
• 2014

Energy performance of building envelope components, including external walls, floors, roofs, windows and doors, is crutial for determining how much energy is required for heating and cooling in a building. Among various building technologies, a green roof system can be a good option for reducing heat gain and loss in new buildings as well as existing buildings for green remodeling. This paper evaluates the performance of green roof systems according to soil depth and Leaf Area Index (LAI) for existing buildings. It also attempts to quantify the energy saving effects on new and existing buildings with different insulation levels. Thermal performance of green roofs is mainly dependent on soil thickness and LAI. Installation of green roofs in deteriorated existing buildings can lead to improvements in roof insulation, due to the soil layer. An increase in soil depth leads to a decrease in heating load, regardless of conditions of vegetation on the green roof. Larger LAI values may reduce cooling loads in the cooling season. Installation of green roof in deteriorated existing buildings showed bigger energy saving effect in comparison to a case in new buildings. A simulation study showed that the installation of green roof systems in deteriorated existing buildings with low insulation levels, due to low thermal performance requirements when constructed, could improve the energy performance of the buildings similar or better to the peformance on new buildings with the most updated insulation standard. Thus, when remodeling a deteriorated building, green roofs could be a good option to meet the most recent energy requirements.

• 한국환경복원기술학회지
• /
• 제24권6호
• /
• pp.109-119
• /
• 2021

Thermal environment of city is getting worse due to severe urban heat island caused by climate change and urbanization. Green roof improves the urban thermal environment and save the cooling energy in buildings. This study presented a green roof combined with a storage system that stores rain-water and supplies water through a wick and evaluated the temperature reduction effect as surface temperature and amount of evapotranspiration. For about a week, the surface temperature using a infrared thermal imager and the evapotranspiration by recording change of module weight were measured at intervals of 30 minutes from sunrise to sunset. The results show that the mean surface temperature of the green roof was 15.4 degrees lower than that of the non-green roof from 12:00 P.M. to 14:00 P.M. There was no significant difference between mean surface temperature of green roof with and without storage system immediately after rain, but more than a week after rain, there was a difference with average of 2.49 degrees and maximum of 4.72 degrees. The difference in daily amount of evapotranspiration was measured to be 1.66 times on average. As drought stress increased over time, the difference in daily amount of evapotranspiration and surface temperature between with/without storage system increased simultaneously. The results of the study show a more excellent cooling effect of green roof combined with the rainwater storage system.

• 한국환경복원기술학회지
• /
• 제26권4호
• /
• pp.51-59
• /
• 2023

Despite countries' efforts to reduce carbon emissions, carbon emissions have increased in recent decades along with energy use, of which building energy uses account for a large proportion. Energy savings are essential as a strategy to reduce carbon emissions in existing buildings. The field experiment on the roof of a building located in Seoul was designed to measure the temperature reduction effect of green roof with rainwater storage tank to reduce cooling energy consumption in summer. The results showed that the mean mean surface temperature under the green roof was 14.77 degrees lower than that of the non-green roof from 13:00 P.M. to 15:00 P.M., which would have a great effect on reducing cooling energy. From 01:00 A.M. to 03:00 A.M., the effect was 3.36 degrees, showing that tropical nights could be improved. The temperature reduction effect due to the rainwater storage system increased by 1.45 degrees during the day and decreased by 0.63 degrees at night. The storage system can be strategically utilized to reduce carbon emissions during the week when cooling energy increases significantly.

• 한국조경학회지
• /
• 제33권5호통권112호
• /
• pp.69-82
• /
• 2005

These studies were carried out (1) to investigate the growth characteristics of Sedum album L. in the field, (2) to propose a suitable shallow peen roof system for this plant, and (3) to evaluate plant growth in the proposed system over the long term. The growth characteristics, such as morphological properties, growth habit, shade tolerance, and flowering, were surveyed. In experimental shallow green-roof systems, the effects of drainage type, substrate type, and soil depth on plant growth were investigated. Then drought tolerance was investigated. After planting Sedum album L. in the proposed system survival rate, cover, and resistance to insects, heal and cold were evaluated for about 2 years. The results of these studies are summarized below. 1. In the field, the aboveground part of Sedum album L. did not die back during the winter. Plant height was 4$\sim$7 cm. Roots were distributed to a depth of 5$\sim$7 cm. Sedum album L. is a compact ground-cover plant that spreads vigorously. Shading condition of less than $30\%$ of full sunlight didn't cause any trouble, but shading conditions above $87\%$ made the shape of the shoots and leaves abnormal. The plant bloomed from June to August and had a rather large compound umbel of white, star-shaped flowers. 2. Two systems, a drainage-blend-10 cm soil depth and a reservoir$\cdot$drainage-blend-15 cm soil depth, performed best in terms of cover, fresh weight, and dry weight. The first has an advantage for green roofs because it is lighter than the latter. 3. In drainage-blend-10 m soil depth and modified reservoir · drainage-blend-10 cm soil depth system no plants died for about 4 months after stopping the irrigation. The visual quality of the latter system was above 5 for 4 months and that of the former was under 5 after 2 months. In the field, however, the drought tolerance of Sedum album L. grown in the former would be enough to withstand the dry season. Considering the urban ecosystem and the importance of healthy growth the modified reservoir $\cdot$ drainage-blend-10 cm soil depth system was finally recommended. This system was composed of a 4 cm thick drainage layer and drain outlets placed at a height of 2.5 cm. 4. In the proposed system, the survival rate was $100\%$, and there was no injury induced by insects and heat. The leaf density decreased a little in winter. Cover increased throughout the year. Sedum album L. was planted with a cover of 72$cm^{2}$ on 3 April 2003; on 16 June 2003 and 15 June 2004, cover was $132.66\pm$5.87 $cm^{2}$(1.8 times) and $886.98\pm$63.51 $cm^{2}$(12.3 times), respectively.

• 한국환경과학회지
• /
• 제19권9호
• /
• pp.1137-1142
• /
• 2010

This study proposes a guideline of a green roof system suitable for the local environment by verifying the growth of Zoysia japonica in a shallow, extensive, green roof system under rainfed condition. The experimental soil substrates into which excellent drought tolerance and creeping Z. japonica was planted were made with different soil thicknesses(15cm, 25cm) and soil mixing ratios(SL, $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$, $P_4P_4L_2$). The plant height, green coverage ratio, fresh weight, dry weight and chlorophyll contents of Z. japonica were investigated. For the soil thickness of 15cm, the plant height of Z. japonica was significantly as affected by the soil mixing ratio and it was shown in the order SL= $P_4P_4L_2$ < $P_7P_1L_2$ = $P_5P_3L_2$ < $P_6P_2L_2$. For the soil thickness of 25cm, the plant height was increased in order to SL < $P_7P_1L_2$, $P_6P_2L_2$, $P_5P_3L_2$ < $P_4P_4L_2$. The green coverage ratio was not observed by soil the mixing ratio or soil thickness. However, the green coverage ratio was 86~90% with a good coverage rate overall. The chlorophyll contents of Z. japonica were not significantly affected by the soil mixing ratio in the soil thickness of 15cm, but were higher in the natural soil than in the artificial soil at 25cm soil thickness. The fresh weight and dry weight of Zoysia japonica were heavier in the 25cm thickness than in the 15cm thickness and in the artificial soil mixture than in the natural soil. The result indicated that the growth of Zoysia japonica was more effective in the 25cm soil thickness with artificial soil than in the 15cm soil thickness with natural soil in the green roof system under rainfed condition.