Cost recovery
Prana recuperators - energy efficient ventilation systems
Cost recovery analysis of recuperators through the example of the combined-type pre-school nursery group "the Sun" at Tsvitna str. 8, the town of Hulyaypole, Hulyaypole disctric, Zaporizhzhya region.
Cost recovery analysis of recuperators in a cold season
Because of growth of prices and rates builders and consumers have faced the issue of necessity to save money which is spent on building-up and servicing of the building. Building costs consist of a great number of values: starting from the cost of document developing and up to the purchase of materials. However, even after finishing the constructionб a lot of money is spent on the functioning of the building and thus there are other expenses which are directed to the exploitation and servicing of the building.
Utility payments and costs of technical maintenance comprise the biggest part of the expenses. Utility payments, in their turn, have their own structure, where the biggest part is taken by heating and hot water supply costs. In average, price for heating makes 35-39% from the general sum of utility payments. It is connected with the high price for service delivering.
The issue of energy efficiency of buildings has arisen as a result of increased amount of such costs. This problem has been considered carefully since the last century. We must imply rational energy expenditure in the notion of "energy efficiency" which will allow us to decrease the costs of its consumption. Apart from decrease of exploitation costs, energy efficiency solves the problem of ecology and preserving microclimate in a building. Energy efficiency of a building means effective use of energy resources, use of smaller amount of energy to provide the same level of energy consumption of buildings.
Conventionally there are two types of heating in Ukraine: centralized and individual. So called heating season is important to create a formula in the first case. That is, the number of days in a year when the heating is on. To simplify the calculation of payback let us take this variant. Last season it lasted from October 16 to April 15, all in all 182 days. In 2020 the rules were changed and now the terms depend on daily-average outside temperature. But in average this value does not differ much every year, that is why we can use the number of days of the heating period as the basis in our calculations.
ample:
Picture №1
(room №3 play- and dining-room in the pre-school «the Sun»).
Starting data:
Area–55,2 m²;
Height –2,8 m;
Volume – 154,56 m3;
Air exchange norm – 1,5units ~232 m³/h;
Air density 1,3 kg/m³;
Air thermal capacity 1005 J;
Average outside temperature in a heating season - 5оС;
Air temperature in the premises +22оС;
Heating season 182 days;
Heating rates according to the counter 1375,06 hrn per 1 gig calorie
Price 1 kW / h: 0,9 hrn (up to 100 kW) 1,70 hrn (from 100 kW);
Calculation:
We define amount of energy, necessary to heat up the air, according to the formula:
Q = c * m * (t2-t1), where
Q - amount of energy,
с - air thermal capacity,
m - air mass,
t1 - outside temperature,
t2 - inside temperature.
Let us consider the necessary amount of air: 232 * 1,3 = 301,6 kg / h
This is the air mass that will have to go through the recuperator during one hour.
Q = 232*1,3*182*24*(22-(-5))*0,00034=12093,63 kJ/period
When using a heating system based on electrical devices:
Provided that this pre-school establishment is heated by warm floors and energy is created with the help of electricity. The price will be the following:
2,98 hrn / h;
71,52 hrn / day;
2145,6 hrn / month,
13016,64 hrn / season (182 days).
This calculation has been done with 100% efficiency factor.
You can also take into account night rates (they comprise 50% of the general rate)
Saving:
You will need a device for the premises which will provide air exchange at 301.6 kg / h. The efficiency factor depends on the specific model and modes of operation and it can differ from 70 to 92%. In average, a recuperator is used in the minimum mode, so let us take 80% efficiency factor of a recuperator as the basis.
Consumption during a heating period with 80% efficiency factor: 12093,63* 0,8 = 9674,90kJ/period.
Saved money:9674,90* 0,90 = 8707,41 hrn
Cost recovery:
Two PRANA-200C recuperators have been installed to provide necessary air exchange and comfort of the consumers. The places of location of the system are shown in picture 1 (room #3 of play- and dining-room in the pre-school «the Sun»).
The price of one PRANA-200C recuperator is 9600 hrn.
Approximate cost of drilling a hole and installing a recuperator is 1200 hrn for 1 piece.
So, total costs will be 9600х2+1200х2 = 21600 hrn.
Cost recovery = 21600/ 9674,90= 2,48, which lasts fifteen months without taking into account costs of energy consumption of the devices and their service maintenance when the system works twenty four hours a day, seven days a week in the above given calculated mode.
2. Using heating system working based on natural gas boiler operation:
1 m3 of natural gas for heating at prices as of 2020 - 4,49 hrn. / m3, when combustion emits 8.6 kW of heat, where natural gas boiler (efficiency factor 93%) keeps 8 kW. And the price of 1 kW of heat for a consumer is 0.52 hrn / kW.
As long as this pre-school establishment is heated by radiators and warm floors, energy is produced from gas. The cost is the following:
0,87 hrn / h;
20,88 hrn / day;
624,4 hrn / month,
3800,16 hrn / season (182 days).
Saving:
You will need a device for the premises which will provide air exchange at 301.6 kg / h. The efficiency factor depends on the specific model and modes of operation and it can differ from 70 to 92%. In average, a recuperator is used in the minimum mode, so let us take 80% efficiency factor of a recuperator as the basis.
Consumption during a heating period with 80% efficiency factor: 12093,63* 0,8 = 9674,90kJ/period.
Saved money: (9674,90/6,8)* 4,49 = 6388,28 hrn.
Cost recovery:
Two PRANA-200C recuperators have been installed to provide necessary air exchange and comfort of the consumers. The places of location of the system are shown in picture 1 (room #3 of play- and dining-room in the pre-school «the Sun»).
The price of one PRANA-200C recuperator is 9600 hrn.
Approximate cost of drilling a hole and installing a recuperator is 1200 hrn for 1 piece.
So, total costs will be 9600х2+1200х2 = 21600 hrn.
covery = 21600/ 6388,28 = 3,38, which lasts twenty two months of the heating season without taking into account costs of energy consumption of the devices and their service maintenance when the system works twenty four hours a day, seven days a week in the above given calculated mode.
omments:
Calculation data are chosen in accordance with climatic region of the district where the object is situated. Each calculation process is done individually with the account of the length of the heating season in the district, average temperature during five days, electricity rates. This calculation is not a template and is designed according to a client's order individually.