Summary of passive strategy
Passive strategy is to regulate dwelling conditions by utilizing solar energy, wind, temperature and humidity in nature environment without mechanical equipment consuming conventional energy. Buildings applying passive strategy accrete with peripheral circumstance other than isolated from surroundings. This essay summarizes common passive strategies and their application in Chinese traditional buildings.
Passive design strategies could be classified into building layout ,envelope thermophysics, and building geometry according to different green building rating tools such as BREEAM, LEED, CASBEE and GBL-ASGB.[11[] Chen, Xi, H. Yang, and L. Lu. ”A comprehensive review on passive design approaches in green building rating tools.” Renewable & Sustainable Energy Reviews 50(2015):1425-1436.]
  1. Building layout design takes account of peripheral obstructions and any other relevant external circumstance to determine the building shape and orientation. Based on self-shading effect and reflectance, building layout influences daylight availability, solar gain, ventilation and thermal performance. It is a vital strategy especially when the location has a high density circumstances.[22[] Li, D. H. W., et al. ”A study of the daylighting performance and energy use in heavily obstructed residential buildings via computer simulation techniques.” Energy & Buildings 38.11(2006):1343-1348.]
    Typical passive strategies:
  1. Transitional space
    Transitional space is generally used in residence in northern China. Winter in northern China is frosty and severe. To resist the coldness, a transitional room is set between the outside and habitable room in the north of the residence as kitchen or storeroom.(Fig.1)
    Fig. 1 Traditional residence in Zhaodong City[33[] Chen.Z, Zhang.SM . ”The Passive Techniques in Chinese Traditional dwellings.” Huazhong Architecture 26.12(2008):204-209.] ①
  2. Direct/ Indirect solar gain
    Related parameters of solar gain are the construction’s shape and layout, building’s orientation, window’s shape, size, orientation (daylighting) and so on.[44[] Lotfabadi, Pooya. ”Analyzing passive solar strategies in the case of high-rise building.” Renewable & Sustainable Energy Reviews52(2015):1340-1353.]
    Since sunlit is a measure to determine the radiation interception, which regulates temperature inside the buildings,[55[] Ralegaonkar, Rahul V., and R. Gupta. ”Review of intelligent building construction: A passive solar architecture approach.” Renewable & Sustainable Energy Reviews 14.8(2010):2238-2242.] one-storey houses constitute most of the residence in northern China to avoid blocking. And the aspect ratio of courtyard is high to gain solar energy at high latitudes. [66[] Tang, Luan.JY, and Liu. ”Discusssion on energy-saving technologies of traditional courtyard dwellings in Northern Henan.” Architecture Scilence28.6(2012):10-13.](Fig.2)
    Fig. 2 Traditional residence in Beijing ②
  3. Ventilation&Shadings
    Residence of Hong Village is elaborately planed considering the high density and the scorching climate. A lake is located to the south of the village as a main entrance and the lanes converge at the wide open lake area. (Fig.3)When the wind in summer flows from the open area to narrow path, the wind pressure strengthens to take the heat away.[3](Fig.4)
    Fig. 3 Residence of Hong Village ③
    Fig. 4 Lanes in Hong Village ③
Another case of residence utilizing nature wind is Pile dwelling of Hmong. The dwelling is suspended up to ventilate better. [77[] Hu, Liang, and Chen. ” Energy saving value research of Pile dwelling-Case stugy of retrofitting of Leyuan.” 2013 Annual meeting of Chinese urban planning 2013.](Fig.5) A similar solution is used in dwelling in Nanjing .[88[] Min.Z. ”Study on ventilation design of Chinese traditional dwellings:Cases study of Nanjing old streets.” Urban development research 22.12(2015).] The floor is staked 30-40cm, so the air could flow under the dwelling from exhaust holes on the footing of the walls by the wind system crossing the village. (Fig.6)
Besides the wind pressure ventilation, thermal pressure ventilation is widely used. Small yard in the centre is slim covered with eaves which reduce solar radiant heat. By means of thermal pressure, air flows from high temperature surrounding to the small yard.[8](Fig.7)