Lag Time of Heat Conduction in Conditions of Growing Greenery Cover on Flattop-Concrete Roof of Single-Room House with Lightweight-Concrete Walls as Constructed on Narrow Space in Bangkok

  •  Pattana Suwansumrit    
  •  Kasem Chunkao    
  •  Surat Bualert    
  •  Chulabut Chanthasoon    
  •  Noppawan Semvimol    


Growing greenery cover on flattop-concrete roof of single-room house with lightweight-concrete walls for lagging heat conduction was experimented during 10 August-30 November 2014 at Kasetsart University on narrow space between the College of Environment and car park buildings in dense-populated city of Bangkok, Thailand in emphasizing on minimum room size of 2.5 m width, 2.5 m length, and 2.5 m height as declared by Building Control Act 1990. The methods of study were conducted by installing air thermometers at one meter above ground in northerly, southerly, easterly, westerly and above roof directions by alternating closing and opening the door and window. The research results found the maximum room temperature ranging 34.5-35.5 oC and minimum 26.5-27.7 oC for both closing door and window, then decreasing almost being equal from degree of opening door and window as well as in conditions of long duration, high intensity, and often frequency of rainfall. Using Pudsaon or Cape Jusmine (Gardenia jusminoides J.Ellis) as grown in growing pot containing coconut flake was feasible because of its characteristics of more consuming phreatophyte with high rate of using water for evapotranspiration process that can absorb surrounding heat through converting process the to become latent heat flux. In consequence, room temperature lowered down to 24.5 oC and following by decreasing lag time from 2 hours to 0.5 hours, and also different lag time from 1-2 hours to 0.5-1.5 hours which were indicated better comfortable living. Closing both door and window or either one could not be conditioned for everyday lifestyle of people in dense and populated Bangkok city. In addition, construction of single-room house with flattop-concrete roof and lightweight-concrete walls were surely eligible to protect heat transferring from hot air outside into room rather than from room to outside, except opening both door and window at the same time

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