I figured out how much it costs to take a shower, drink tea, wash clothes, whether it’s necessary to save water and electricity, and to what extent.
“The pressure in the water supply system at the point of consumption in multi-apartment residential buildings for cold water ranges from 0.03 MPa (0.3 atm) to 0.6 MPa (6.0 atm);
for hot water – from 0.03 MPa (0.3 atm) to 0.45 MPa (4.5 atm);”
I measured it at home – 2 liters fill in 12 seconds. Therefore, 10 liters per minute.
Generally, the pressure of cold water can reach 17-18 l/min, which is about 3 atm.
Cost of water by meter:
cold – Mosvodokanal 29.16 RUB per cubic meter.
hot – MOEK – 135 RUB per cubic meter
Permissible hot water temperatures at the tap – acceptable limits of hot water temperature should be from 65 to 75 degrees Celsius.
Comfortable temperature range at the mixer – from 40 degrees to 50 degrees Celsius. At 65 degrees – skin burns in 2 seconds.
Let’s assume tap cold water runs very cold – 8 degrees. Usually, it ranges from 8 to 18 degrees, depending on pipe insulation and the season.
We’ll calculate for winter (8 degrees) and for summer (18 degrees)
WINTER:
50*x+8*y=45, x+y=1
50*x+8*(1-x)=45,
42x=37
x=88% hot water
y=12% cold water
SUMMER:
WINTER:
50*x+18*y=45
x+y=1
50*x+18*(1-x)=45,
50x+18-18x=45
32x+18=45
32x=27
x=64% hot water
y=36% cold water
Thus, comfortable shower temperature in SUMMER costs about
0.64*135RUB/cubic meter + 0.36*29.16RUB/cubic meter = 96 RUB per cubic meter or about 10 kopecks per liter
Thus, comfortable shower temperature in WINTER costs about
0.88*135RUB/cubic meter + 0.12*29.16RUB/cubic meter = 122 RUB per cubic meter or about 12 kopecks per liter
At 10l/min, a cubic meter is used up in 100 minutes.
Therefore, an hour of showering costs 57 rubles in summer and 73 rubles in winter.
If the shower temperature is raised from 45 to 50 degrees,
50*x+8*y=50, x+y=1
x=72%, y=28%.
0.72*135RUB/cubic meter + 0.28*29.16RUB/cubic meter = 108 RUB.
Therefore, the cost increases by 20 rubles / cubic meter.
Taking a bath – about 200 liters, i.e. on average 21 rubles.
Washing dishes – every 5 minutes of the tap running costs about 6 rubles.
If the pressure is higher than mine (not 10l/min but 17l/min), then all absolute amounts should be multiplied by 1.7.
Regarding electricity, it’s more interesting – an iron (1200W) on for 18 minutes or a kettle (2300W) on for 10 minutes uses as much energy as a 15W energy-saving bulb running continuously for a day in the hallway.
The cost of a 15W bulb on for a month – 47 rubles. If you have a standard 60W bulb, then four times more.
That comes back to the question, is it worth turning off the lights at night?)
At a water temperature of +5°C, it takes about 4 minutes plus or minus a few seconds to boil 1 liter of water.
At a water temperature of +25°C, it takes about 3 and a half minutes plus or minus a few seconds to boil 1 liter of water.
The power of a modern electric kettle is 2000-2200W, let’s take the average – 2100W. This means that in 1 hour, the kettle consumes 2.1 kW/hours.
At a cost of one kWh equal to 4.68 rubles, in 1 hour the kettle will spend 9.8 rubles. For apartments with electric stoves (like mine) the cost of electricity is 3.28 per kWh, which makes the figures 1.4 times lower (in brackets).
Let’s calculate:
At a water temperature of +5°C, boiling 1 liter of water will cost 1.4 rubles (1 ruble).
At a water temperature of +25°C, boiling 1 liter of water will cost 1.68 kopecks (1.2 rubles).
So, tea for guests costs 2.5 rubles including Lipton bags (sugar not included). Well, this is taking me off track now)
If you need to heat up warm water, the cost will drop even more.
Washing machine consumes from 1 to 1.5 kW/h. With laundry done 3 times a week for 2 hours, this results in 24 to 36 kW/h per month. Thus, one load of laundry costs about 9.3 rubles (6.6 rubles), and per month – 112-168 rubles (80-120 rubles).
Hi, I'm Rauf Aliev. 