A Furnace(3m x 2m x 2m) needs to be pre-heated from 25C to 1650C with a burner. The furnace is made out of 10mm mild steel. The furnace is insulated with refractory 10mm thick with k=0.2 W/m k. Ignore flue losses. How much energy is required to achieve this and what will the heat losses be through the refractory and mild steel? The ambient temp will be 25C. Make assumptions where required and show a detailed calculation.