The total light transmittance of hand lay-up glass fiber-reinforced polymer (GFRP) laminates for building construction was investigated for the purpose of two architectural applications: translucent load-bearing building envelopes and the encapsulation of photovoltaic (PV) cells in structural and lightweight GFRP building skins. Spectrophotometric experiments on unidirectional and cross-ply GFRP specimens in the range from 0.20 to 0.35 volume fraction and artificial sunlight exposure experiments on encapsulated amorphous silicon PV cells were performed. An analytical model for the GFRP light transmittance was developed and predictions agreed well with results obtained in the PV experiments. The total fiber content in the laminates was the major parameter affecting light transmittance, with the fiber architecture having little effect. 83% of solar irradiance in the 300-800-nm band reached the surface of amorphous silicon PV cells encapsulated in GFRP laminates with a reinforcement weight of 820 g/m2 over the cells, demonstrating the feasibility of conceiving multifunctional GFRP structures.