Regulate Kitchen Ventilation More Effectively with Demand Control

Each year, the U.S. Environmental Protection Agency (EPA) gives out its Emerging Technology Award. The honor is intended to recognize an innovative product that meets “rigorous performance criteria to reduce energy usage and greenhouse gas emissions.”¹ The 2015 winner was recently announced, and it was awarded to demand control kitchen ventilation (DCKV).

This innovative technology is changing the way restaurants and other food service businesses operate. Kitchen ventilation is the largest user of energy in the average commercial service business, and the EPA found that ENERGY STAR-certified demand control kitchen ventilation systems can reduce restaurant ventilation energy consumption by 60% or more.²

How demand control kitchen ventilation systems work
Demand control kitchen ventilation uses advanced sensors and variable speed controls to offer significant reductions in commercial energy use and carbon emissions. While most restaurant ventilation systems operate at only one or two speeds, regardless of actual need, DCKV responds to real-time kitchen volume.

When kitchen hoods are in greater use, usually during busier meal rushes or heavy preparation periods, a demand control kitchen ventilation system ramps up. In contrast, during slower periods, the system winds down, saving energy and money in the process.

Ventilation in commercial kitchens can account for half of the HVAC energy use in restaurants and dining facilities. Conventionally, kitchen exhaust fans and the associated makeup air handlers are switched manually and left to run at full speed for all operating hours. The power needed to exhaust air in a kitchen hood increases by a cube factor with respect to air flow. This means that even a relatively modest reduction in air flow can result in large fan energy savings. In addition to direct savings due to reduced fan energy, every cubic foot of air exhausted from the building must be replaced by another cubic foot of conditioned air. Reducing the amount of air exhausted from the building saves energy that would have been required to condition newly introduced outside air.

Demand control kitchen ventilation systems provide automatic, continuous control over fan speed by responding to signals that are picked up by temperature, optical or infrared sensors. Those sensors work by monitoring cooking activity and smoke and steam levels or directly communicating with cooking appliances. During full load cooking, the system tells fans to run at 100% until smoke and steam are removed and the temperature is more comfortable.³

Technical benefits of demand control kitchen ventilation
There are many benefits of installing an ENERGY STAR-certified DCKV system, not the least of which include significant reductions to monthly utility bills. But there are many other advantages beyond the cost savings, including:

• Automatic, continuous control over fan speed – ¬a DCKV system uses information from advanced sensors inside the kitchen to modulate fan speed according to detected cooking operations
• A reduction in the supply and exhaust air volume, which lowers overall energy costs – just a 20% reduction in airflow volume can yield 45–50% in annual fan energy savings
• System communication – some DCKV systems afford users the ability to track energy consumption and make necessary adjustments to maximize system performance
• User controls – these provide visual indication of a fault in the same room

Practical benefits of demand control kitchen ventilation
Beyond its capability as an energy efficient, cost-saving piece of restaurant equipment, demand control kitchen ventilation offers several benefits that impact the way employees and guests experience their work or dining environment.⁴

• More comfortable work environment – a restaurant kitchen can get hot, stuffy, crowded and choked by effluent and steam. Demand control kitchen ventilation helps to relieve those problems, making for a more comfortable work environment for employees, which can also lead to higher productivity, accuracy and service.
• Cleaner dining room air – in many restaurants, the excess steam and heat from the kitchen can spill into the dining room, negatively affecting guest experience. Modern DCKV systems are extremely efficient at removing particulate matter and other hazards that might waft into the dining room.
• Reduced noise – when traditional ventilation systems run at full speed all day long, they create a level of ambient noise that negatively impacts the ability to communicate in a kitchen. But DCKV regulates fan speed depending on need, thus cutting back on noise during slower periods of the day.

When demand control kitchen ventilation makes the most sense
Demand control kitchen ventilation works to vary the speed of the fans based on temperature, smoke and steam, increasing speed when necessary and reducing speed when cooking decreases.⁵ As a result, the longer a kitchen stays open and the higher the number of hoods, the more beneficial demand control kitchen ventilation is and the faster it will pay off. A business owner can determine if demand control kitchen ventilation offers a significant return on investment by totaling the number of hoods on the premises and calculating how many hours these appliances are running.

Working with a contractor to install demand control kitchen ventilation
Any restaurant owner or manager who wants to cut costs, improve energy efficiency and foster a more comfortable work and guest environment by installing a DCKV system should consider working with an experienced HVAC contractor.

HVAC contractors who have experience working with DCKV systems can help find the proper equipment for an individual restaurant’s need, install the technology properly, maximize efficiency and cost advantages, and keep the system well maintained throughout its lifetime.

For more information on finding and working with an HVAC contractor, please reference "The Complete Guide to Working with a Lighting or HVAC Contractor" eBook from PG&E.

1. U.S. Department of Energy
2. U.S. Department of Energy
3. Gaylord Ventilation
4. Food Service Technology Center
5. MeLink