Two-core block design reduces heat conduction by what percentage?

• A. 1% to 2%
• B. 3% to 4%
• C. 5% to 6%
• D. 7% to 8%

Answer: (B)

Two-core block design reduces heat conduction by creating hollow channels inside the block, which introduces air gaps that resist heat flow. Heat moves much more readily through solid material than through air, so replacing part of the solid mass with these air-filled cavities lowers the overall conduction path. The two cores cut the conductive area and add thermal resistance, but the effect is modest because heat can still travel around the cavities and through the outer material. In typical construction, this translates to about a 3% to 4% reduction in heat conduction, which is why that range is the best fit. Pushing the reduction higher would require more drastic insulation changes (more cores or filling cores with insulating material), while much smaller reductions wouldn’t reflect the practical impact of adding hollow cores.