Control criteria of electrochromic glasses for energy savings in mediterranean buildings refurbishment

Abstract

During the next decades the refurbishment of old buildings will be an essential way to contribute to the global improvement of buildings energy performance indicators. Within this context, the present paper is focused on the use of electrochromic (EC) windows, an emerging technology alternative to shading devices, to control solar gains in buildings located in Mediterranean climates. The optical properties adjustments of the EC glasses are discussed based on the incident solar radiation. The ESP-r building energy simulation software was used to study the energy savings resulting from the application of electrochromic windows, considering the comparison of several windows solutions (single, double-glazing and EC windows) and windows orientations (East, South and West). In addition, different transition ranges for the optical properties of the EC glasses are assessed through the analysis of the energy needs for space heating and cooling. The main conclusion is that EC technology is an effective option in cooling dominated buildings. The impact of EC windows is highly dependent on facade orientation, being a valid option particularly in the cases of the East and West facades. For these facades, the control set point found to be effective corresponds to an incident solar radiation on the glass of 150 W/m 2 to impose a total coloured state. For the South facade the results show no significant advantage of using EC windows.

The Challenge for Building Integration of Highly Transparent Photovoltaics and Photoelectrochromic Devices

“…Tavares et al [119,120] demonstrated the usefulness of switchable windows in terms of energy savings in air conditioning for sun-oriented (South, West and East) façades.…”

Analysis of Heating and Cooling Loads of Electrochromic Glazing in High-Rise Residential Buildings in South Korea

“…However, the drawback of most electrochromic glazing products is their low speed of response. It requires five minutes for a 10 cm × 30 cm glass [18] to be colored, and eight minutes and 12 min for a 1.2 m × 0.8 m glass to be colored and bleached, respectively [19]. On the contrary, a few recently released electrochromic glazing products can be colored within three minutes.…”

A comparative energy analysis of three electrochromic glazing technologies in commercial and residential buildings

“…The key variables in defining this type of control scheme are the optical properties of the intermediate dark states and the insolation thresholds at which the control switches to these states. Additional testing was done to determine the appropriate values of these parameters, which are based in part on control thresholds modeled in previous studies [63]. In these tests, a series of controls are constructed with varying propensities to switch to darker states, i.e.…”