When it comes to restaurant equipment, there are a lot of choices. For any given kitchen task, there are multiple technologies and multiple vendors. Today, let’s examine dish cleaning. The big decision to be made here is on technology – chemical sanitization vs. thermal sanitization. In other words, do you pay for chemicals or pay for hot water? Setting aside the relative efficacy of these approaches, let’s consider the cost of hot water, and more specifically, the energy required to heat water for cleaning dishes.
The SiteSage chart here ranks the equipment in a real fast casual restaurant by its cost of operation – notice the “Water Booster” and “Dishwasher” are both in the top 5 (note: the colors represent changes relative to the past – orange means usage is up, green means usage is down and grey means usage is about the same). Based on our work, we’ve found the chart above to be common – as you can see, the cost of heating water for dish cleaning is one of the largest uses of electricity in a restaurant, if not the single largest use. In some cases, the cost for dish cleaning will surpass heating and cooling costs. Surprised? We were – it really adds up.
A low temp, chemical sanitizer solution may require about 6,000W to operate, while a hot water sanitizer will use four times as much energy – perhaps 25,000W to operate. At $.10 a kWh (ignoring the impact on demand charges, which may be substantial), the incremental cost for the extra-hot water is over $5,000 a year. A modest demand charge could boost that figure by another 50%.
To the left, see a comparison of the electricity used by a kitchen Roof Top Unit (top) vs. the electricity used by a hot water booster (below). The booster actually uses more energy than the RTU, which means that your high-temp booster could be costing you as much to run each month as the entire cooling cost of your kitchen!
These costs can be mitigated somewhat if gas-fired on-demand water heaters are used instead of an electric booster, but such a retrofit requires substantial upfront capital cost.
So what’s the recipe for reducing electric bills in restaurants? Based on the significant energy costs for a high temperature dish cleaning approach, it is worth carefully considering the real costs of that approach in comparison with the savings achieved by eliminating chemicals. Even from an environmental standpoint, while it’s excellent to remove cleaning chemicals from outflow, the energy used to heat the water may be produced using significantly more impactful fossil fuels. The efficacy of the two approaches should also be compared – if, for example, the dishes must be run through a longer cycle, or run through twice, obviously that doubles the actual cost of that approach.
Equipment-level purchasing decisions like these can add up to huge costs down the line, so using real operational data to compare equipment costs and effectiveness across your locations can save you a bundle. Restaurant energy can be managed intelligently, just as other supply costs are.