Thermal performance of precast foam concrete integrated with green roofs system

Abstract

The increase in urban temperature because of the urban heat island phenomenon affected energy usage for the building sector. Most of the energy usage in the building is for the air conditioning system to achieve thermal comfort. It is necessary to reduce the cooling load by minimizing heat gain to the building so that the air conditioning system uses less energy consumption. Passive design with a green roof system offers a solution to reduce heat gain from solar radiation through the roof. However, only a few buildings have implemented a green roof system in the tropics, especially in Indonesia, and the literature found on this subject is also inadequate. This research studies the thermal performance of precast lightweight foamed concrete as a roof structure integrated with a green roof system through experimental modeling. We constructed two prototype rooms with the precast foam concrete panel as the roof. One prototype uses a green roof and the other without a green roof. We expose the prototypes to an open environment with direct sunlight for 3 days. The air and surface temperatures inside and outside the models were measured continually at the 10-second intervals. The thermal performance of the green roof is evaluated by comparing the thermal responses of the models during the exposure. The results show that the green roofs significantly reduce the heat load from solar radiation during the day.

Green Roof Development in ASEAN Countries: The Challenges and Perspectives

“…The high temperatures in Indonesia appear to be a major issue in Stage 1 for Indonesia. Jakarta, as the metropolitan city in Indonesia, has average daytime temperatures that could reach up to 35 • C. The surface of a roof exposed to the sun during the day can be affected by temperatures as high as 50 • C [51]. In order to limit the heat absorption into buildings, the development of GRs in Indonesia is important.…”

“…Several GR research studies and developments, which are categorized as Stage 3, are also being conducted. A study by Munir found that the use of lightweight foamed concrete and a green roof reduces construction loads and cooling loads for air conditioning systems [51]. Moreover, as an alternative to concrete, corrugated zinc roofing could be used as the base of a building's green roof.…”

“…-GRs can reduce energy consumption in buildings by up to 57%, reduce roof surface temperatures when compared to bare roofs up to 23.8 • C, and reduce the room temperature to 14 • C. It should be noted that heating load reductions can be influenced by substrate [73], vegetation [76], and insulating material [81]. Some researchers describe alternative material such as lightweight concrete deck that can improve GR properties [40,51]. -GRs aid in water management, owing to their high water retention potential and increased runoff quality.…”

“…Aside from climate, material selection has an influence on decreasing performance due to temperature. In Indonesia, Munir [51] revealed that lightweight foamed concrete in combination with roof slabs for green roofs has positive results on cooling as well as on construction loads, which will also impact cost effectiveness. Based on a simulation study, another alternative from Yuliana [53] claimed that corrugated zinc with plants can be used instead of green roof concrete.…”

“…The materials used also affect the performance of GRs at inside room temperatures. Munir [51] used lightweight foamed concrete for GRs with an effective outdoor decrease up to 10.2 • C. The use of GRs can result in significant energy savings since the temperature of a room that applies GRs deviates less from the comfort zone than the temperature of a room that does not apply GRs. This allows cooling to operate more efficiently in spaces with GRs.…”