Dynamic Solar Energy Transmittance for Water Flow Glazing in Residential Buildings

摘要

The U-factor, the solar energy transmittance (g value) and Visible Transmittance (VT) are window properties required to calculate the energy performance of a building. But the relative importance of these properties depends on site and building specific conditions. The ratio between visible transmittance and g value is a fixed value in traditional double glass panes. In cold climates the designer should select the highest g value to reduce heating so that winter solar gains can offset a portion of the heating energy need. A low g value is the most important window property in warm climates. In moderate climates, with significant air conditioning costs or summer overheating problems, windows with lower g values reduce summer cooling and overheating, but they also reduce free winter solar heat gain. Coatings provide double glass panes with static values so that building designers can use available design guidelines and simplified methods to choose the most appropriate type of glass according to the climate zone, the use and occupancy of the building. The aim of this paper is to study the behavior of water flow glazing (WFG) in regards to the g value and the visible transmittance. Circulating water through the chamber absorbs infrared radiation, reduces the temperature of the interior glass pane and provides control over the thermal load striking the surface. Dynamic g values and VT coefficients can be achieved in WFG by means of changing the flow of water and fluid dyes. This paper includes a new methodology to choose the most appropriate water flow glass depending on its range of g value and VT in residential buildings. This methodology will end up in a simplified method to select thermal and optical features of water flow glazing before running a simulation.