Just like car manufacturers come out with a "design only" car that is meant not to drive but for conceptualization and to push the engineering team, I wanted to see how many incandescent light bulbs it would take to actually heat a home... in case that your heater goes out in the middle of winter and you find yourself with nothing but 500 illegal light bulbs and way too many power strips.
Incandescent bulbs light bulbs only convert 10% of their energy use towards putting out actual light, the other 90% is wasted and converted to heat. So let's say that a 60 watt light bulb puts out 54 watts of heat to a room per hour (60 x 90%). Here is a chart on how many kWh of heat is produced from different quantities of light bulbs
Incandescent bulbs light bulbs only convert 10% of their energy use towards putting out actual light, the other 90% is wasted and converted to heat. So let's say that a 60 watt light bulb puts out 54 watts of heat to a room per hour (60 x 90%). Here is a chart on how many kWh of heat is produced from different quantities of light bulbs
| # of light bulbs 10 100 1,000 10,000 100,000 1,000,000 10,000,000 | Energy produced in kWh 0.54 5.4 54 540 5,400 54,000 540,000 |
So to compare, a furnace produces 75,000 BTU of energy per hr for a mid-size home or roughly 22 kWh of energy. That means we would only need about 500 light bulbs to produce the same amount of heat as our furnace is supplying! At $1.50 per 60 watt bulb, it would cost an initial investment of $750 for 500 light bulbs. When we hooked up all our power cords in a fire safe manner and plugged in our lamps, 500 light bulbs would draw 30 kWh, which is 8 kWh MORE than our 75,000 BTU furnace. Plus our furnace would last about 20 years longer than our bulbs. BUT if you are in a jam and have no heat, now you know how many bulbs you need to keep warm at night!
