Greetings, dear professionals and amateur self-builders!
The other day, I argued with a friend and made a small calculation, believing that cooking on gas is cheaper, but the numbers put me in a stupor. I tried to approach the whole calculation in a comprehensive manner, taking into account the little things, and gas really came out more expensive for me, more precisely, the use of a gas stove, so we figure it out ...
The initial data are as follows:
1. The energy spent on cooking is approximately 300-400 kW * h / month, which is equivalent to 30-40 cubic meters of gas, as we spend on cooking. This is due to the fact that the release of 1 kW of energy is spent on average 0.10115 cubic meters. gas.
2. The volume of the room where the cooking appliance is located is key, and you will see why later. My kitchen and living room are in the same room, plus the staircase, corridor and hallway are also not fenced off by doors. And this is very important, since a gas stove is a gas appliance to which the gas workers themselves impose increased requirements in terms of ventilation.
As a result, the area covered by this requirement is 48 sq. M. (kitchen-living room 35, hallway 5, corridor with a staircase 8 sq.m.). The air volume in this room is 48 * 3 (height) = 144 cubic meters.
Here's my plan:
Now, the calculation itself ...
The calculation is simple and you can do it yourself in 15-20 minutes.
The amount of energy for cooking I take 300 kWh per month and multiply by 12, I get 3600 kWh / year. In cubic meters of gas, this value is 30 * 12 = 360 kW * h / year.
Next, consider the price ...
Electricity price: 4.25 rubles / kW, which means the cost of cooking per year: 3600 * 4.25 = 15300 rub.
Gas price: 6,559 rubles / cubic meter, which means per year: 360 * 6,559 = 2361 rub.
At first glance, everything is fine in favor of gas, but the gas workers forced me to make another large exhaust hole, and an additional the hood is an additional air exchange and this is the fresh air that needs to be heated during the heating season or 7 months in year! It would seem a trifle, but the numbers are scary. The problem is that as soon as a gas appliance appears in the room, please increase the ventilation of the air up to three times the volume and there is no getting away from it, otherwise no one let the gas down! Gas workers demand!
To calculate, we need to know the average temperature in winter, it is -5 ° C, and in the room +24.. + 25 ° C, respectively ΔT = 30 ° C.
When using an electric stove, how much air is actually in the room, that one needs to be ventilated (144 cubic meters), and for the gas point we take into account a threefold volume: 144 * 3 = 432 cubic meters.
The last action remains - to calculate the energy that is spent on heating the air, which is constantly replaced with fresh air by ventilating the room.
E = (ΔT * C * V * t), where:
C is the heat capacity of air;
t - time period (in hours)
To convert the values obtained from the formula from Joules to kWh, we need to divide the value by 3,600,000 (3.6e + 6).
A) For electricity: E = (30 * 780 * 144 * 7 (heating months) * 30 (days in a month) * 24 (hours in a day)) / 3600000 = 4717.4 rubles / year
B) For gas: E = (30 * 780 * 432 * 7 (heating months) * 30 (days in a month) * 24 (hours in a day)) / 3600000 = 14152.32 rubles / year
According to the figures, we see the dependence that the colder it is in the house, the more you need to pay for heating.
TOTAL
When using an electric oven, we will spend 4717.4 on heating the ventilated air and add here the cost of energy spent on cooking, which was considered slightly higher: 4717.4 + 15300 = 20017,4 rub / year
Now we count the gas: 14152.32 + 2361 = 16,513.32 rub / year
We received figures that show the total costs in the complex when operating two kitchen stoves and, it would seem, electricity loses by 3,500 rubles per year, but wait ...
Firstly, I coordinated an additional gas appliance with the gas service and I don’t remember how much this rush resulted, but certainly not 3,500 rubles, but secondly, I lifted the second pipe with a hole 250 * 250, which I brought out through the roof of the house for the sake of this ventilation only, so that the gas workers would approve the gas point. And I spent about 60,000 rubles for additional ventilation on bricks, cement, sand, abutments to the roof, a cap and other trifles.
As a result, it turns out that the cost of operating this gas stove will approach the cost of using electric in 20 years!
It turns out amazingly!