With an energy crisis looming over the world, we tried to make the situation better by improving the efficiency of something as basic as lighting. This project harnesses the fact that the human sees light blinking rapidly enough as a still light. This principle was applied to 10Watt LEDs used for room lighting.
A microcontroller was used to switch LEDs on and off very quickly. Power consumption of the LEDs was predicted for different combinations of on-off times for the LEDs. We hypothesised that perceived brightness wouldn’t change because the LEDs were off for a short time-period. Experiments were conducted with the LED for 1 millisecond(ms) on, 1ms off; until 1ms on, 12ms off. This was repeated for on times from 2-8ms. The power consumption and brightness of the LEDs were measured for all combinations. Power consumption of the LEDs reduced drastically. Contrary to the hypothesis, the brightness also reduced in combinations with longer LED off times (Click on graphs for clear images)
3 efficient on-off combinations were identified in 3 categories – low, medium and high brightness. They produced 42%, 20% and 18% respectively greater brightness per watt consumed than non-blinking LEDs.
Incandescent lamps account for 25% of power consumption in lighting. They consume 6563 terawatt-hours annually. Replacing these with non-blinking LEDs results in a saving of 4923 terawatt-hours! If blinking LEDs are used, there would be an additional 328 terawatt-hours of power saved (assuming minimum efficiency), more than Germany’s annual power consumption!
As always, to view the entire project, click here. Cheers!
Air Conditioners (A/C) use roughly 1 trillion kWh of power annually. The project seeks to reduce power consumption of A/Cs. The proposal is a movable false ceiling. It will be lowered when the occupant is sleeping to reduce the volume of the room allowing the A/Cs to cool faster. The question which had to be addressed was ‘How much will reducing the volume of the room at night using a movable false roof, reduce power consumed by air conditioners?’ The hypothesis was that there was a relation between the time taken to cool the room and its volume.
The experiment tested energy savings by using a high power A/C to cool a smaller volume. Two boxes of thermocol were built, simulating a room. The first box represented the original volume of the room. The second box’s volume was adjustable. 4 tests were conducted, changing the output temperature on the A/C and the volume of the second box in each test.
All the tests pointed to two important results:
The lower the volume, the greater the energy saving. There was an average power saving of 0.14 kWh/hour translating into a 14% reduction in power consumption.
The lower the A/C output temperature the greater the energy saving.
Large scale implementation of such a device will result in massive energy savings worldwide. In an escalating electricity cost scenario, this device can help households to reduce power costs without compromising on comfort.
To view the entire project report, please click here. Cheers!