Oven Efficiency – E. Goldrick & A. Grossman
PAST: History of the Oven
In Ancient times, people first began cooking over an open flame of the fire that was placed in the ground. Soon, simple masonry constructions were built to house the wood and food. These earth ovens were often located within the homes, and were dug into the ground then heated using hot rocks, coal or ashes. While this form of cooking was friendly to the environment, the actual process of cooking was slow and laborious. Today archeologists look for earth ovens as an indicator of human civilization.
Wood burning stoves were the next major step in cooking development, but the abundance of smoke that was produced forced inventors to figure out an enclosed cooking system, leading to wood burning ovens. In 1735, a French architect by the name of François Cuvilliés, designed the Castrol stove (also known as the stew stove) which completely enclosed the fire. Iron plates were positioned over the holes and containers were heated by being placed directly onto the hot surface. While this did little for time efficiency, it did help improve the air quality making it more environmentally friendly.
Cast-iron ovens grew in popularity around 1728, but at first were large and bulky making them impractical for the average kitchen. Almost exclusively for the wealthy, these new ovens reduced the amount of wood burned by one-third. In 1834, Stewart’s Oberlin stove was patented, which was one of the first successful compact iron stoves invented. Iron ovens went through several derivations before the invention of the gas stove in 1826 by a British inventor, James Sharp. By the 1920s, gas ovens were found in most households. Also, with the invention of enamel helped improve the aesthetics of the appliance.
Not until the late 1920s to early 1930s did the electric oven begin to compete against the gas. When electric ovens were actually invented is somewhat disputed by historians (possibly 1882), but the first one was put into service at the Windsor Hotel in Ottawa in 1892. The invention of resistor heating coils was a major design improvement as a result of the electric oven.
With all of the new developments in cooking, energy and time efficiency have become integral in creating better quality and more sustainable ovens.
PRESENT: History of the Oven
Today consumers have a variety of choices in their ovens from brand and overall aesthetics to energy and time efficiency of the appliance. When deciding between a gas or electric oven there are many factors to take into consideration. Electric is often preferred over gas in order to avoid breathing in the toxic byproducts of gas combustion in the house. Gas appliances need to be effectively vented in order to avoid this. These ovens often use halogen electric elements which provide the instant-on/off that consumers expect today. In addition, gas ovens often have a glow-bar that continuously runs in order to reignite the gas flame should it blow out, which uses a significant amount of energy to do.
Electric ovens tend to be more energy efficient and the temperature controls are more accurate. Gas ovens need to provide oxygen for combustion in order to remove combustion gases from the oven which in turns uses more air flow which in turn lowers their inefficiency.
According to the LBNL study:
-A standard electric oven has a cooking efficiency of about 12%
-A self-cleaning electric oven has a cooking efficiency of about 14%. (it has more insulation in the oven case)
-Standard gas ovens have cooking efficiencies of about 6%
-Self-cleaning models 7% (If the self-cleaning feature is used often in an oven, the Energy Factor goes down, due to the energy use for self-cleaning.)
-Electric clocks in both gas and electric ovens can dramatically lower the annual energy factor, as a result of consuming an average of 4 watts and operating all the time. Also, the pilot lights on old gas ovens dramatically reduce the annual energy factor.
In order to maintain good efficiency here are some helpful tips when using your oven:
- Buy a self-cleaning oven, but reduce the use of the self-cleaning feature.
- Buy a convection oven, this allows cooking at a lower temperature because the heat is more uniformly distributed.
- Avoid buying an old gas range, cooktop, or oven that has a pilot light (pilot lights are no longer included on new cooking equipment)
- With an electric cooktop, match the element diameter to the pot or pan. Using a 6-inch pan on an 8-inch element will waste 40% of the energy.
- With an electric cooktop, make sure your pots and pans have flat bottoms to maximize heat transfer.
- Keep your stove and oven clean to improve performance.
- Defrost foods before cooking to reduce cooking time and energy use, unless cooking instructions suggest otherwise.
FUTURE: Sustainable oven choices
In an era when preserving the planet and human life has transformed from trend to necessary social responsibility, heightened awareness leads to better choices for a sustainable future. The oven appliance has made some major transformations over the last decades and will continue to progress further as we try to meet certain energy efficient goals. In February 2009, amid a wave of executive actions establishing his administration’s priorities, President Barack Obama ordered the U.S. Department of Energy to raise the federal standards for energy efficiency in a variety of appliance categories. Ovens and microwave ovens were of course listed within the category. This declaration by the President occurred because our nation was failing to comply with the Energy Policy and Conservation Act of 975 mandating scheduled updates for appliance efficiency standards.
The future will be more and more stringent when it comes to adhering to energy efficiency policies in appliances. ENERGY STAR is a qualification that many commercial organizations strive to adhere to. The products use less energy, save money and help protect the environment. Each ENERGY STAR qualified electric oven can save businesses 1,870 kWh annually, or an average of $190/year on utility bills. Each ENERGY STAR qualified gas oven can save 30 MBtu annually, or an average of $360/year on utility bills. Commercial ovens that have earned the ENERGY STAR are about 20 percent more energy efficient than standard models
Beyond the future of convection, electric, and gas oven efficiency ratings requirements, there is a prediction for solar powered ovens to become popular in the future. Not only would solar powered oven aid the average American household on cost and energy savings, but it would aid third-world nations, as well. They would not have to rely on cutting down trees for wood, or fuels that are either too expensive to afford or non-existent. Many nations are facing deforestation crisis because they rely on wood to cook. “Something on the order of two billion people cook with wood or wood-related products. The earth’s forests cannot handle the demand, nor can the earth’s atmosphere handle the additional carbon that these fires send up into the air in the form of smoke. It is impossible to calculate the degree of horror entailed in the human suffering in poor communities as cooking fuel vanishes or becomes impossibly expensive. The profound need, combined with the simplicity of most common solar cookers, strongly suggests that the solar cooking movement will grow by many orders of magnitude.” Many people who are doing the cooking, primarily women, are inhaling the fumes from the wood-burning smoke and dying, as well.
In additional to solar cooking advancements, steam ovens and speed ovens are becoming more and more popular. They are more time, health and energy efficient than ovens of the past. Cooking with older equipment can consume a lot of electricity. More modern models of electric ovens, fryers and steam cookers can be far more energy-efficient. Our appliances are finally catching up to our fast-paced, demanding lifestyles. Speed ovens cut the time of cooking in half, which saves the amount of energy used during the cooking process.
Aesthetically, these appliances are becoming smaller and sleeker looking. These smaller products cut down on the amount of materials needed create it. Less materials used for the body of the ovens means less waste at the end of it’s life.
As time moves forward, better appliance choices are becoming available to us. Human beings are becoming aware of these more sustainable choices. It is our hope that the awareness of this important issue will grow and we can contribute to a more sustainable future.
- Ancient Greek portable oven, 17th century BCE
- Google Images
- Viking-Gas Oven: http://www.vikingrange.com/consumer/products/product.jsp?id=prod8880168
- Viking-Double Electric Oven: http://www.vikingrange.com/consumer/products/product.jsp?id=prod11160311
- Miele-Convection oven: http://www.mieleusa.com/products/models.asp?cat=3&subcat=7&menu_id=14&oT=36&active=Our%20Products&subm=Home%20Appliances&thirdL=Cooking%20Products&fourthL=Ovens
- Solar oven: http://eartheasy.com/sport-solar-oven-kit
- Speed oven: http://www.mieleusa.com/usa/cooking/speed-ovens/product.asp?cat=3&subcat=26&model=639&series=68&nav=&snav=&tnav=&oT=193&menu_id=15&active=Our%20Products&subm=Home%20Appliances&thirdL=Cooking%20Products&fourthL=Speed%20Ovens&fifthL=Products&
- Steam oven: http://www.mieleusa.com/products/models.asp?cat=3&subcat=19&menu_id=11&oT=38&active=Our%20Products&subm=Home%20Appliances&thirdL=Cooking%20Products&fourthL=Steam%20Ovens&