Studying kitchen environments for improving energy performance and the health of home and professional cooks.
Status: Current
Funding Sources: U.S. Department of Energy
Project Objective
The goal of this project is to advance our understanding around the health and well-being impacts of kitchen environments in terms of thermal comfort and air quality, leveraging the advantages of laboratory and field study settings.
Project Results
We anticipate that this research can inform future policies and practices, leading to healthier, more efficient and kitchen environments. This work successfully demonstrated an approach for comparing the pollutant exposure impacts of cooking with gas versus induction cooktops, showing that induction used 50% less energy, emitted no NOX and fewer ultrafine particles, though likely more PM2.5. The findings around commercial kitchens are offered to encourage the adoption of energy-efficient technologies and practices in the food service industry, and to fill critical gaps in understanding the co-benefits of energy efficiency improvements on the health and performance of workers in commercial kitchens.
This work demonstrated an approach for comparing the pollutant exposure impacts of cooking with gas versus induction cooktops. Results show that induction used 50% less energy, emitted no nitrogen oxides and fewer ultrafine particles, though likely more PM2.5.
Significance to Industry
Cooking produces air pollutants, generated by cooking appliances and also by the cooking process itself, that contribute to substantial exposure and health hazards. While fully electric kitchens are praised for the elimination of harmful gases resulting from gas combustion, cooking with electric resistance and induction cooktops may still produce ultrafine-particles and other pollutants. Furthermore, understanding kitchen environments is important due to often difficult working conditions and significant environmental footprint associated with culinary spaces. In the United States, restaurants employ approximately 13 million people, accounting for nearly 10% of the national workforce. These workers frequently experience extreme indoor air temperatures and high relative humidity, compounded by the presence of unhealthful air pollutants generated from both cooking processes and cleaning agents. Beyond worker well-being, kitchens are centers of intensive energy usage, using up to five times more energy per square foot than office buildings. Nationally, this equates to $10 billion in energy costs and the emission of 44 million tons of CO2e annually. As the trend toward in-house kitchens continues to grow within non-restaurant sectors, for example in corporate offices and healthcare facilities, optimizing these environments is essential for improving public health, energy efficiency, and sustainability.
Research Approach
We conducted the following two studies in collaboration with Lawrence Berkeley National Lab:
Comparing Pollutants from Gas and Induction Cooktops and the Effectiveness of Recirculating Range Hoods
We conducted a laboratory study of air pollutant concentrations resulting from cooking with gas or induction cooktops, in a setting that approximates a home kitchen, and also tested the effects of two recirculating range hoods with filters. A meal of pasta, plant-based sauce, and stir-fried broccoli was cooked three times for each cooktop and hood combination. We measured nitrogen oxides (NOX), carbon dioxide (CO2), particles, and numerous elements in volatile complex organic compounds (VOCs) during and after cooking activities. We found that induction cooking used half as much energy, produced no discernible NOX, and significantly reduced ultrafine particles (< 100 nm) and CO2 compared to gas cooktops. VOCs did not significantly differ between gas and induction. Both recirculating range hoods substantially reduced all particle sizes when cooking with either fuel, with larger reductions with gas cooking; one of the range hoods also substantially lowered some VOCs.
Field study of Kitchen Ventilation and Assessment of Indoor Environmental Quality in Ten Restaurants
We recruited ten commercial kitchens in the San Francisco Bay Area, ranging in size from the smallest restaurant that only seats 15 customers to larger ones that have posted capacities of several hundred patrons. The study included walkthroughs to identify energy-saving opportunities that focus on food preparation and kitchen ventilation improvements. We measured the airflow of exhaust hoods and visually assessed their performance by observing the cooking effluent plumes and inspecting the surroundings, with the aim of documenting deficiencies with the ventilation systems. We also measured a range of indoor air pollutants, including fine and ultrafine particulates, nitrogen oxides (NOx), carbon dioxide (CO2), and carbon monoxide (CO). We also set up devices to characterize the thermal environment in the kitchen. We invited the kitchen staff to complete a survey. On separate visits, we spent up to eight hours collecting time-integrated indoor air samples around lunch and dinner service, measuring indoor air pollutants including aldehydes, VOCs, and semi-volatile organic compounds (SVOCs).
As may be expected from such a wide range of kitchens, the research team identified numerous areas for improvement. For example, half of the visited kitchens had insufficient or completely absent air conditioning systems, and an additional three had undersized or ineffective cooling systems, leading to inefficiencies in maintaining indoor temperatures. Air temperatures were between 64 and 91°F (18 – 33°C), and one kitchen had air temperatures higher than 87°F (30.6°C) that would exceed California heat safety regulations. The study also documented concerning levels of indoor pollutants, for example, the measured concentrations of ultrafine particles in all ten kitchens during cooking hours surpassed the World Health Organization reference values. While no single factor determines indoor air quality, we found that exhaust hood performance and usage, ventilation system design, and the types of cooking and fuel are all important contributing factors. Surprisingly, most kitchen staff who responded to the researchers’ survey were satisfied with their kitchen environments.
Publications and Reports
Li, J., Zhao, H., Russell, M.L., Delp, W.W., Johnson, A., Tang, X., Walker, I.S., Singer, B.C., (2024). Air pollutant exposure concentrations from cooking a meal with a gas or induction cooktop and the effectiveness of two recirculating range hoods with filters. Indoor Environments, Volume 1, Issue 4,100047. https://doi.org/10.1016/j.indenv.2024.100047.