80% of a Cabin's Power Goes Somewhere You Forgot

When sizing power for modular housing, people count lights, sockets and office equipment first. A measurement published by the EU LIFE Zero Energy Mod project says otherwise: a standard 20-foot container at the Spanish base in Afghanistan burned about 15,000 litres a year, of which lighting was only 20%. The other 80% went to heating and cooling. What sets the plant's capacity is the air conditioner, not the light bulbs. The conclusion holds in both hot and cold climates — only the load switches from cooling to heating. Prefab envelopes are usually thinner than masonry, so load per square metre is higher; miss this line item and the whole system comes out undersized, precisely in the weather when it matters most.