Surveys of Microwave Ovens in U.S. Homes

The U.S. Department of Energy (DOE) is conducting test procedure and energy conservation standard rulemakings for microwave ovens.1 A “microwave oven” is a cooking appliance that is capable of cooking or heating food using microwave energy. These units can be self-contained counter-top units; units placed over a conventional range with a fume hood attached (also known as over-the-range microwave ovens); or built-in units that are installed surrounded by kitchen cabinetry. They can also include “convection microwave ovens,” which are cooking appliances capable of cooking or heating food using both microwave energy and convection heat transfer in a single compartment. Such appliances have the capability of heating food using microwave energy or convection heat transfer or both microwave and convection in a single cooking cycle. These units generally offer a “convection,” “bake,” or “combo” cooking mode on the user interface. 

DOE divides products under analysis into classes by the type of energy used, capacity, or other performance-related features that affect consumer utility and efficiency. Installation types are grouped as (1) countertop and (2) built-in and over-the-range. For the DOE test procedure and standard rulemaking, two types of microwave ovens are of interest, specifically: 

• Microwave-only ovens and countertop convection microwave ovens
• Built-in and over-the-range convection microwave ovens 

DOE must decide whether the test procedure for convection microwave ovens should test only microwave mode or also convection mode. Therefore, DOE is interested in how often convection-capable microwaves are used in convection mode. While some consumer data exist on microwave ovens generally, there are no data that allow a differentiation between types of microwave ovens, their form of installation, or consumer use of the convection mode. 

In order to supplement the microwave data currently available, LBNL undertook data collection of its own using online surveys. We sought details of microwave oven ownership and use, such as: 

• Distinguishing characteristics of households with convection microwave ovens 
• Frequency and duration of cooking events for each microwave oven product class to estimate how much energy is consumed by each class.