The energy-savings potential of electrochromic windows in the UScommercial buildings sector

Abstract

Switchable electrochromic (EC) windows have been projected to significantly reduce the energy use of buildings nationwide. This study quantifies the potential impact of electrochromic windows on US primary energy use in the commercial building sector and also provides a broader database of energy use and peak demand savings for perimeter zones than that given in previous LBNL simulation studies. The DOE-2.1E building simulation program was used to predict the annual energy use of a three-storey prototypical commercial office building located in five US climates and 16 California climate zones. The energy performance of an electrochromic window controlled to maintain daylight illuminance at a prescribed setpoint level is compared to conventional and the best available commercial windows as well as windows defined by the ASHRAE 90.1-1999 and California Title 24-2005 Prescriptive Standards. Perimeter zone energy use and peak demand savings data by orientation, window size, and climate are given for windows with interior shading, attached shading, and horizon obstructions (to simulate an urban environment).Perimeter zone primary energy use is reduced by 10-20% in east, south, and west zones in most climates if the commercial building has a large window-to-wall area ratio of 0.60 compared to a spectrally selective low-e window with daylighting controls and no interior or exterior shading. Peak demand for the same condition is reduced by 20-30%. The emerging electrochromic window with daylighting controls is projected to save approximately 91.5-97.3 10 12 Btu in the year 2030 compared to a spectrally selective low-E window with manually-controlled interior shades and no daylighting controls if it reaches a 40% market penetration level in that year.

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

“…Moreover, the daylight glare index and lighting energy have been investigated in the context of indoor light to represent the characteristics that can control the range of visible rays [6,9]. According to the results of simulations of office buildings in the United States (US), 10-20% of the energy saving effect is obtained at the perimeters of buildings [10], and at least 54% of the energy can be saved in a Mediterranean climate [11]. A study showed that 37-48% more lighting energy can be saved compared with manual control-type blinds [12].…”

Electrochromic glazing and walls for reducing building cooling needs

“…Using the DOE-2.1 software, LBNL conducted, during the same period, another interesting study, which aimed to quantify the potential impact of electrochromic glazing for saving of primary energy in commercial buildings in the United States, in 16 different climate zones in California, and in 6 different climates in the United States (Lee et al, 2004). The simulation was conducted having as a building type the prototype developed by the LBNL for some ASHRAE standards in force in the United States.…”

Dialectic Form Finding of Passive and Adaptive Shading Enclosures

“…These features, in general, have led to the development of adaptive building skins, which already prove to have significant operational energy saving potential, by as much as 51% [59,60]. The logic of adaptive performance is compelling: it promotes reduced energy consumption and increased occupant comfort [61]. Although the performance of adaptive enclosures might depend upon the occupant's preferences, its efficacy meets or exceeds that of a fixed system.…”