The gaps between the fine strips would be sufficient to allow natural light in, whist the strips (in combination) would be sufficient to provide a discernible image when viewed from a suitable distance. The strips themselves could be light emitting (a string of LEDs for example) or merely reflective (which would only work during the day). An eInk reflective coating would allow the advert to be regularly changed. A combination of both light emitting and reflective techniques might be optimum to allow the adverts to be seen clearly no matter the level of sunlight.
Another advantage of this is that the strips would prevent excessive sunlight, which heats the building and causes increased air conditioning costs.