Performance of double-circulation water-flow window system as solar collector and indoor heating terminal Chunying LI 1

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E-mail: [e-mail] 
Performance of double-circulation water-flow window system as solar 
collector and indoor heating terminal 
Chunying Li
1
, Cuimin Li
2
 (), Yuanli Lyu
3
, Zhongzhu Qiu
4
 
1. School of Architecture & Urban Planning/BenYuan Design and Research Center, Shenzhen University, Shenzhen, China
2. Department of Municipal Engineering, School of Environmental Science and Engineering, Suzhou University of Science and Technology, 
Suzhou, China
3. Department of Civil, Architecture and Environment, Xihua University, Chengdu, China
4. College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai, China 
Abstract
Double-circulation water-flow window is a novel-designed solar-building-integrated energy saving 
system. The window part is composed of four layers of glass panes and 2 layers of flowing water, 
which contributes to building energy conservation by utilizing solar energy for domestic hot water 
preheating and regulating indoor heat gain through window. In heating season, warm water is 
supplied to the water-flow window cavity and it releases heat to the room through the innermost 
glass pane. Thermal, energy and economic performance of the compact double-circulation water- 
flow window was numerically analyzed in the present study. Results showed that direct solar 
transmission could be largely reduced with water-flow window, compared with common curtain 
wall. The year-round solar collection efficiency was 16.2% for the external water circulation and 
4.3% for the internal water circulation. The predicted static payback period was around 7 years, 
with the extra investment of water-flow window over common curtain wall and the saving in 
electricity charge taken into consideration. For higher inlet water temperature at the internal 
window cavity during heating season, the predicted payback period was slightly longer, since part 
of the heat was lost to the outdoor environment. The results showed preferable potential of 
double-circulation water-flow window system in buildings with stable hot water demand and 
high-density energy demand.