Smart buildings using 5G and Internet of Things (IoT) acknowledge themselves as one of the most innovative byproducts occasioned by the Fourth Industrial Revolution, and are seen as the forward solution to the built environment issues once if fully implemented. Among these effects, radiation stem as the invisible one, but with a direct impact as dwellers inside a smart building will be continuously exposed to radiation. Several studies have already shown that a myriad of health issues can emerge from radiation, causing biological damages such as DNA alteration and hormone imbalance which could escalate to depression, anxiety disorders to various other illnesses including cancer and tumor. When smart buildings are actualized, building materials can influence the plethora of Electromagnetic radiation as these materials also exhibit Electromagnetic properties. The paper aims, through a pragmatic approach, to evaluate and quantify the influence of common building materials inside a simulated smart building using Computer Simulation Technology (CST). The study found that Electromagnetic Radiation (EMR) produced by 10 GHz is much higher than 2.45 GHz for all building materials and natural, sustainable materials such as wood and earth produced 2-3 V/m less EMR and overall scattering man-made building materials. The dissipation of EMR became more pronounced with higher frequency with concrete showing less dissipation in EMR compared to glass although the latter produced more. Steel showed significant difference in EMR when compared to other materials and a high level of scattering with stagnant radiation inside the space.