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Energy saving with Optic-Variable Wall for stable air temperature control

Wang, Cheng, Guo, Xiaofeng, Zhu, Ye
Energy 2019 v.173 pp. 38-47
absorption, air conditioning, air temperature, buildings, energy conservation, heat, heat tolerance, heating systems, insulating materials, solar radiation, summer, ventilation systems, winter
Optic-Variable Wall (OVW) holds the property of tunable reflectivity to solar radiation. By allowing more solar radiation absorption in winter while maintaining high reflection in summer, OVW can help energy-saving during the HVAC of buildings. In this paper, the energy saving potential with OVW for stable air temperature control is investigated. Annual meteorological conditions are adopted in the comparison of cooling and heating loads. The effects of properties of OVW and Indoor Air Temperature (IAT) are discussed. It is concluded that OVW is able to simultaneously reduce heating and cooling loads. The optimum onset temperature of OVW is half the temperature zone lower than IAT. With the adoption of OVW, the heating load is close to the case of OFW (Optic-Fixed Wall) with low reflectivity; the cooling load of OVW provides close effect as using high-reflectivity OFW. In terms of tuning temperature, narrow temperature zone is favorable for the reduction of HVAC load. Comparing with OFW, the relative reduction of HVAC load with OVW is independent of conductive thermal resistance, corresponding to the thickness of insulation layer. The results offer new choices for the passive design of green buildings and show directions for future development and performance improvement of OVW.