When choosing a refrigerated display case, customers most often compare the price of the equipment. But for a store, another factor is more important—the total cost of ownership, that is, the sum of the initial investment and electricity costs over the entire period of operation.
Let’s take a look at two versions of the same refrigerated display case: one with 6-mm-thick glass and one with a 4+10+4-mm insulating glass unit, where there is a 10-mm air space between the two panes of glass.
Why do insulated glass units save energy
The main difference lies in the glazing's ability to transfer heat.
Standard clear glass 6 mm thick typically has a U-value of ? 5.9 W/m?·K. For a insulated glass unit consisting of two panes of clear glass with an air cavity, this value is approximately 3.0–3.2 W/m?·K. The lower the U-value, the less heat penetrates into the refrigeration compartment.
CARBOMA puts this principle into practice. For example, the KC70 series of pastry display cases is available with both glass and insulated glass. The designers directly attribute this design choice to a reduction in refrigeration load and operating costs.
Let's calculate five years of operation
Suppose the temperature in the store is +25 °C, and inside the display case it is +2 °C. The temperature difference is 23 °C.
For every square meter of glazing, the heat flow through single glazing will be approximately:
5.9 ? 23 = 136 W.
Through 4+10+4 insulated glass:
3.1 ? 23 = 71 W.
The difference is about 65 watts of heat load per square meter of glass.
Assuming an average coefficient of performance (COP) of 2 for the refrigeration system, the compressor will require approximately 33 W less electrical power. With round-the-clock operation, this amounts to about 290 kWh per year, or approximately 1,450 kWh over five years for each square meter of glazing.
At an electricity cost of 5.9 rubles per kWh, the savings will be around 8,600 rubles over five years per square meter of glass. Or 32,700 rubles over five years of operation for a KC70 VV 0.9 display case, which has a glazed area of approximately 3.8 square meters.
What about the higher price?
If a display case with insulated glass costs 120,000 rubles, a similar model with regular glass will cost 98,000 rubles. The initial savings are 22,000 rubles.
The initial price difference will be recouped within three years of operation at the facility. The larger the glazed area, the higher the indoor temperature, and the more expensive the electricity, the faster the glass unit will recoup the initial extra cost..
That is precisely why, when comparing refrigerated display cases, it is important to consider more than just the purchase price.
Single glazing reduces the initial investment. Insulated glazing reduces ongoing operating costs.
For a store that plans to use the equipment for five, seven, or ten years, the total cost of ownership often proves to be a much more important factor than the difference in price between display cases on the day of purchase. If we consider the economies of scale when the fleet of display cases totals about 1,000 units, the savings amount to tens of millions of rubles.
Are you planning to expand your coffee shop or store, or start a new project?
CARBOMA helps businesses save money with product display solutions based on energy-efficient technologies
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