Novel mobile communication technology such as 5G will provide a more efficient and reliable platform for the development of the Internet of Things. However, microwaves in the range of 5G frequencies are strongly attenuated by modern energy-efficient glazing found in most recent buildings. This paper presents major steps towards microwave transparent glazing which allows a flawless transmission of 5G frequencies while maintaining the thermal energy efficiency of the window. Several double glazing windows with different properties were fabricated with a laser treatment and their effect on the signal attenuation in the frequency range between 0.7 and 3.5 GHz was measured. The results showed that the laser treated windows produced a transmission of the microwave as good as a non-coated window. In comparison, an energy-efficient window without laser treatment reduces the signal strength up to 300 times.