Thermal load reduction in buildings using transparent honeycomb insulation

Improving the thermal performance of building envelopes is essential for reducing energy consumption and maintaining indoor thermal comfort across varying climatic conditions. This study presents an analytical and numerical investigation of thermal load reduction in buildings using opaque insulation and transparent insulation materials (TIM), with emphasis on polycarbonate honeycomb systems. A lumped heat balance-based thermal model is developed to account for conductive, convective, radiative, ventilation and solar heat transfer through walls, roofs, windows and doors. Simulations are carried out for a representative residential room located in three distinct Indian climatic zones: Leh (cold–dry), Bareilly (composite) and Hyderabad (warm–humid). Overall heat transfer coefficients (U-values) are evaluated for bare, opaque-insulated, and TIM-clad walls for insulation thicknesses ranging from 5 to 20 mm. The results show a consistent reduction in U-values with increasing insulation thickness, with opaque insulation providing the lowest values and TIM-clad walls offering a balanced combination of thermal resistance and solar transmission. Monthly analyses of solar irradiance, heat flux and thermal load indicate that insulation significantly reduces winter heat loss in cold climates and limits summer heat gain in warmer regions. A 20 mm insulation thickness is identified as optimal across all climates. The findings demonstrate the potential of transparent honeycomb insulation for energy-efficient and passive solar building applications.