Returning to the Homestead Example Problem, it’s time to focus on figuring our electricity requirements. For this, it’s best to start by estimating high and then paring things down as we refine our design.
The following table is a rough estimate for a family of four in a 2000 ft^2 house.
| Peak Wattage | Usage frequency | Daily energy (kWh) | |
|---|---|---|---|
| Refrigerator | 600 | 8 hours/day | 4.8 |
| Microwave | 1500 | 10 min/day | 0.25 |
| Oven | 5000 | 3 hours/week | 2.1 |
| Stove (range) | 2000 | 5 hours/week | 1.4 |
| Food processor | 300 | 1 hour/week | 0.04 |
| Slow cooker | 200 | 10 hours/week | 0.29 |
| Home heating | 300 | 8 hours/day | 4 |
| Water heating | 4500 | 6 hours/day | 27 |
| Lights (halogen, LED) | 130 | 3 hours/day | 0.4 |
| Food processor | 300 | 1 hour/week | 0.04 |
| Computer | 200 | 4 hours/day | 0.8 |
| TV | 125 | 4 hours/day | 0.6 |
| Air conditioning (if required) | 600 | 8 hours/day | 4.8 |
| Deep Freezer | 600 | 12 hours/day | 7.2 |
| Ceiling fans (3) | 200 | 8 hours/day | 1.6 |
| Clothes washer | 1200 | 1 hours/day | 1.2 |
| Dish washer | 300 | 1 hour/day | 0.3 |
| Clothes dryer | 5000 | 1 hour/day | 5 |
| Cell phone | 5 | 2 hours/day | 0.01 |
| Computer | 200 | 4 hours/day | 0.6 |
| Vacuum cleaner | 1200 | 1 hour/week | 0.17 |
| Power tools | 1000 | 2 hours/day | 2 |
| Toaster | 1000 | 10 min/day | 0.17 |
| Stand mixer | 300 | 1 hour/week | 0.04 |
| Misc. (clocks, radio, etc.) | 200 | 4 hours/day | 0.6 |
| 26,720W (This is HUGE!) | 64.4 kWh |
Please note that I am not advocating the use of any of these items – I just want to give a complete list of the most common appliances we use today. If you choose to use a dryer instead of a clothesline, or a dishwasher instead of washing by hand, that’s fine. This is not a forum for us to judge each other, it is a forum for developing design strategies.
These numbers are first iteration estimates, which err on the high side. This serves several purposes: first, it prevents us from overly restricting the design too early in the process (remember, we are still in the first iteration of the design cycle); second, as appliances age they become less efficient.
Tune in tomorrow for Part 2 where we refine the estimate to more reasonable numbers.
Comments:
5 Comments -Show Original Post Collapse comments
Anonymous said...
Keep up the good work, I have you in my favorites list.
1:43 AM
PeakEngineer said...
Appreciate it, anon. Thanks for the support.
6:19 AM
Green2Go said...
Wow look at the number for Hot Water Heater! Glad we opted for Solar.
11:02 AM
PeakEngineer said...
Yeah, I was shocked at the numbers for hot water and ovens. I knew they were high, but the numbers surprised me.
6:07 PM
DJEB
DJEB said...
Nice resource, thanks!
9:43 AM












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