Restaurants can use their kitchens’ waste heat to power their dishwashers and heating, ventilation, and air conditioning (HVAC) units with energy recovery systems. By harnessing wasted energy, they can save money and improve efficiency.
Leveraging Energy Recovery Systems in Kitchens
Every commercial kitchen has ovens, fryers, warmers and refrigerators that generate waste heat. Typically, an extraction fan moves that hot air outside to keep temperatures down, where it dissipates in the environment, wasting energy. A power recovery unit uses mechanical ventilation to reclaim otherwise-expended sensible and latent heat.
The fast-casual restaurant chain Nando’s uses waste heat to heat its buildings and water tanks. Any one of its kitchens generates enough heat to power over 30 homes for one year on average, so this strategy results in substantial savings despite the high initial cost. After a year-long trial at the Didsbury branch, the company rolled out the heat exchange system to 14 other stores, indicating the return on investment was satisfactory.
Repurposing waste heat makes building systems more energy-efficient, lowering utility bills and carbon emissions. Since HVAC units account for over 40 percent of a building’s total power consumption, the savings are substantial. While the process is not technically free, it occurs passively without incurring additional costs, which maximizes gains.
HVAC systems are less efficient in variable conditions because they must work twice as hard to achieve the same result. Mechanical ventilation prevents fluctuations by adjusting the temperature and humidity of incoming and outgoing air, reducing hardware strain and extending equipment lifespan.
Recovering waste heat typically involves installing a specialized rooftop ventilation unit. However, restaurant owners can also reclaim wasted power by combusting municipal solid waste. The heat converts water to steam, which a generator uses to produce electricity. Packaging, used personal protective equipment and food scraps can act as the fuel.
The waste-to-energy process turns nonrecyclables into electricity or fuel. It mitigates carbon dioxide emissions by reducing fossil-fuel reliance and preventing methane generation during decomposition. Also, it decreases the volume of scraps destined for landfills. Modular systems are portable, so they can burn unprocessed, mixed solid waste locally.
Advantages of Using Energy Recovery Ventilators
The main benefit of deploying a heat exchange system in a commercial kitchen is power consumption reduction. The HVAC system and water heater use less electricity from the grid, lowering utility bills. While generating waste heat by cooking and powering equipment technically costs money, recovering that thermal energy incurs no additional expenses.
A heat exchange unit improves HVAC efficiency by helping keep the indoor air temperature and relative humidity consistent. It preconditions the inbound outside air using the outbound interior air, heating, cooling, humidifying or dehumidifying it depending on the season. It may even improve air quality through passive filtration.
These seemingly small changes make the kitchen a comfortable place to work, improving retention among back-of-house professionals like line cooks, chefs and dishwashers. Given that 75 percent of restaurants say hiring and retention are their most significant difficulties, the improvement could be drastic. Replacing one worker can cost up to two times their annual salary, so this approach could also lead to cost savings.
The type of energy recovery system a restaurant installs could affect these gains. For instance, hybrid heat recovery equipment—which consists of multiple units in a single system—may be more efficient than its conventional counterpart. Studies show it can save more than 90 percent of wasted energy, depending on the application.
Other appliances may also impact potential long-term savings. For example, an inefficient chiller may consume more power without producing comparable waste heat, leading to minor losses and preventable hardware wear. Operators should consider how their building and kitchen systems will interact before implementation.
Restaurants Can Turn Waste Heat Into Cost Savings
While success stories like Nando’s demonstrate the real-world benefits of power recovery, owners and operators should consider costs carefully. Larger chains may stand to benefit more than small mom-and-pop restaurants due to the scale of their waste heat production. Even though returns are inevitable, heat exchange units require a significant upfront investment.
Ellie Gabel is a freelance writer who also works as the associate editor for Revolutionized.com. She loves keeping up with the latest innovations and advancements in science, tech and sustainability. When she’s not hard at work, you can find her playing video games and spending time with her husband and their cat.
