Estimated weekly domestic hot water (DHW) usage
5 Person Household
If you plan to use a solar thermal system to
heat domestic hot water, an estimation of the building's consumption
must be made in order to properly size the system. We have done some
analysis to predict how much a 5 person household will use.
Summary
| Common uses |
Number of people (person) |
Number of cycles (cycles/person/week) |
Total cycles (cycles/week) |
Hot water (liters/cycle) |
Total hot water (liters/week) |
Average hot water (liters/day) |
Total energy (kWh/week) |
Average energy (kWh/day) |
| Dishwasher |
5.0 |
1.4 |
7.0 |
30.4 |
212.7 |
30.4 |
8.9 |
1.3 |
| Clothes
washer |
5.0 |
1.0 |
5.0 |
14.6 |
73.2 |
10.5 |
3.1 |
0.4 |
| Shower |
5.0 |
7.0 |
35.0 |
84.7 |
2,964.4 |
423.5 |
124.2 |
17.7 |
| Miscellaneous |
5.0 |
7.0 |
35.0 |
0.8 |
28.2 |
4.0 |
1.2 |
0.2 |
| Total |
3,278.5 |
468.4 |
137.4 |
19.6 |
Temperature
Conditions
| Description |
Value |
Units |
| Cold water
from the utility grid |
12.8 |
°C |
| Hot water
from the domestic hot water
tank |
49.0 |
°C |
| Temperature difference |
36.2 |
°C |
Calculation notes:
- Shower flow rate equal to 7 liters/minute for
15 minutes
- Dishwasher based on Whirlpool large capacity
model DU850SWP
- Clothes washer based on Whirlpool super
capacity model WTW5100S
- Miscellaneous uses might include hand washing,
coffee or tea making, cooking, etc.
- Liters/cycle indicates amount of hot water used
from the domestic hot water tank
- Total mixed temperature water used (not shown)
may be more than hot water used
- Temperature of cold water from the utility grid
and hot water from the DHW tank may vary based on climate and season
For a list of common DHW tank manufactures, please see our Solar
Power Resources page.
Domestic hot water consumption will vary based
on many variables (number of occupants, habits of those occupants,
climate, appliances, etc.). In order to more accurately
predict domestic hot water production, you will need tweak this
estimation for your conditions. We have a spreadsheet available in
several file
formats to assist you.
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