Ask Energenie

August 1999

Table of Contents

1. I try to make energy-conscious decisions for my home's electrical needs, but I don't know a volt from a watt. Could you explain some basic electrical terms?
2. What is movable insulation?
3. What is the best exterior lighting source?
4. The recent increase in gasoline prices has caused me to drive more conservatively. Is there anything I can do to minimize fuel consumption besides simply driving less?
5. I need to replace my water heater soon because it is leaking. What can you tell me about tankless water heaters?
6. The gasket on my refrigerator door is cracked and does not seal tightly. Can it be repaired, or do I need to look for a new refrigerator?
7. I am remodeling a home in the country and have the option of using propane or electric appliances. I am interested in conserving energy but also in saving money. Can you give me any guidelines on which form of energy might be best for my country home?
8. I generate a lot of used oil on my farm. What can I and other rural businesses do with large quantities of used oil?

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1. I try to make energy-conscious decisions for my home's electrical needs, but I don't know a volt from a watt. Could you explain some basic electrical terms

"Even the most basic elements of electricity can be confusing, but understanding them is important when you are communicating about your electrical needs and appliances," said Bruce Snead, extension specialist in residential energy at Kansas State University. "The following definitions and explanations should help you master the terms," he said.

Ampere is a standard unit of electrical current. It is the flow rate of a current past a given point in an electrical circuit. A similar comparison is the quantity of water passing by a given point in a garden hose.

The two types of electrical current are direct current (DC) and alternating current (AC). It is important to know what type of current operates a particular appliance. Most plug-in home appliances use AC current, while most battery-powered appliances use DC. Some brush-type motors and portable appliances can run on either.

Voltage is a measure of the electrical force that causes the current to flow through a wire. It results from the difference in potential between two points on a circuit. Voltage can be compared to the water pressure causing the flow in a garden hose.

Voltage is a rating for batteries, such as a 12-volt automobile battery. Most homes have 110-volt lights and plug-in receptacles. Large appliances like electric stoves and dryers are often rated at 220 volts.

Watt is a unit of power. One watt is the amount of power produced when a force of one volt drives a current of one ampere. A typical light bulb is rated in terms of the watts of power it needs to operate. A watt is not a measure of the amount of light given off by a light bulb.

Watt-hour is a measure of energy. It is the amount of power drawn over time. If a 100-watt bulb operates for one hour, it uses 100 watt-hours of electricity. A kilowatt-hour is 1,000 watts of power used in one hour, or 100 watts operating for ten hours.

Your monthly utility bill will list the number of kilowatt hours consumed. A typical household uses 500 to 1,000 kilowatt-hours a month.

"Having some concept of electrical terms will simplify decisions and purchases involving your electrical needs," Snead said. "This knowledge will also save you time, money and energy."

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2. What is movable insulation?

"Movable insulation is a versatile window covering that allows heat gain during winter, when it’s beneficial, and minimizes heat gain in summer, when it’s unwanted," said Richard Nelson, extension specialist at Kansas State University.

Insulating windows can make a significant difference in your energy bill, since windows are to blame for much of summer heat gain and winter heat loss. This is due to the low R-value of the glass pane.

"R-value measures resistance to heat gain or loss," Nelson explained.

"A typical insulated wall has an R-value anywhere from 12 to 19, while a double-pane window has an R-value of about 2," he said. "By using movable insulation within the window frame, you can nearly double the R-value. This will help reduce your home’s overall heating and cooling load."

Movable insulation is divided into two types — interior and exterior. Examples of interior movable insulation are thermal curtains, shades, shutters, and window quilts.

Shades and shutters keep out (or retain) the most heat, but also cost more than curtains and window quilts. Shades are most effective if they are properly sealed along the edges of the window. Interior shutters are usually made of polystyrene or a foam sheathing encased in wood or metal, and can triple the R-value of a window.

The most common type of exterior movable insulation is shutters.

"Most people who use movable insulation place it inside their home," Nelson said. "The advantages of interior insulation are protection from the weather and simplicity of operation."

"Exterior movable insulation has advantages as well," he said.

Exterior shutters provide additional security to your home and can reflect more sunlight into your home during winter months. They also do a better job of reducing solar load in the summer. However, shutters generally cost more than interior insulation, and are subject to constant weathering.

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3. What is the best exterior lighting source?

"The best type of lighting depends on the desired use," said Gene Meyer, extension mechanical engineer at Kansas State University.

"For example, out of all light sources, low-pressure sodium lamps have the highest lumen per watt output (amount of light produced per watt of energy consumed)," he said. "However, the distinct yellow color of low-pressure sodium lamps limits their use to area lighting, such as parking lots and security lighting."

High-pressure sodium lamps have improved color. They are not as efficient as low-pressure sodium lamps, but are still effective light sources and are better suited for general purpose lighting.

"Metal halide lamps are the preferred light source for sports activities," Meyer said. "The light produced by these lamps is slightly blue in color, but looks more natural than the yellow light of sodium lamps. The output and efficiency of metal halides is lower than either of the sodium lamps but much improved over the less expensive mercury vapor lamps."

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4. The recent increase in gasoline prices has caused me to drive more conservatively. Is there anything I can do to minimize fuel consumption besides simply driving less?

"Yes," replied Richard B. Hayter, director of Engineering Extension at Kansas State University. "There are several steps you can take to cut fuel consumption."

These fall into three basic areas — car maintenance, driving habits and lifestyle preferences.

"If you expect to save on fuel consumption, you must keep your car in top condition," Hayter said. "Follow these maintenance tips."

• Tune up your car according to the manufacturer's recommendations.

"Keep in mind that the type of driving you do determines the frequency of maintenance," he said. "Tune up your automobile more often if you drive it mainly on short trips rather than on the highway."

• Change the oil and check air, fuel and oil filters at recommended intervals.
• Check tire pressure weekly. Use the maximum recommended pressure; under-inflated tires decrease fuel economy.

"Your driving habits can have as much effect on fuel consumption as automobile maintenance does," Hayter said.

He gave the following recommendations:

• Anticipate traffic patterns to minimize frequent braking and accelerating. Traveling at a constant speed uses less gas than slowing and accelerating.
• Avoid excess idling, such as letting your car warm up for several minutes before you drive it.
• Accelerate slowly if traffic allows. "Jack rabbit" starts waste gas and save very little time.

"You can also cut fuel consumption by altering lifestyle preferences," Hayter said.

• Car-pool or ride public transportation if available.

"Compare driving routes with neighbors and co-workers. You may find that your schedules coordinate, saving everyone fuel and giving you time to visit or work during the trip," he said.

• Bicycle or walk instead of driving.
• Shop locally. Many people comparison shop but don't realize that the price of any purchase also includes the cost of the trip to buy it.

"Driving five to ten miles to save a dollar is not economical," Hayter added.

• Drive at moderate speeds. Driving 60 instead of 55 mph on a 10-mile trip saves less than one minute of driving time and uses more fuel.
• When car-pooling, drive the car that gets the best gas mileage. For example, six people traveling in one car that gets 15 miles per gallon is more economical than driving two cars that each gets 25 miles per gallon.
• Consider the total operating cost when purchasing a vehicle.

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5. I need to replace my water heater soon because it is leaking. What can you tell me about tankless water heaters?

"Tankless, or demand, water heaters don't have storage tank, so they heat water as it is used, on a demand basis," said Gene Meyer, extension mechanical engineer at Kansas State University.

"Because there isn't a storage tank, this type of water heater can save from 10 to 20 percent on the cost of heating water," he said.

A family of four uses about 100 gallons of hot water a day. Over the course of a year, the cost to heat this amount of water will vary from $90 to $700, depending on the price of energy.

"If your fuel prices are high, the savings gained from a tankless water heater will be significant," Meyer said.

Tankless heaters are available in either point-of-use or central styles.

Point-of-use heaters are installed near each area that requires hot water. This minimizes plumbing for new construction. The other type, central tankless heaters, supplies water for the entire house.

"Tankless water heaters generally cost $200 to $500 more than conventional water heaters," Meyer said.

While this may seem like a large premium to pay, the fuel savings may justify the additional cost over the course of just a few years.

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6. The gasket on my refrigerator door is cracked and does not seal tightly. Can it be repaired, or do I need to look for a new refrigerator?

"Most likely, the gasket is beyond repair, but you can have qualified repair person install a new gasket," said Doug Walter, president of Kansas Building Science Institute, Manhattan.

"The cost of a new gasket, including installation, will likely be $100 or more, but this cost is justified unless your refrigerator is very old," he said.

A crack or tear allows air to escape from a portion of the gasket. Without the air support, the gasket collapses and the magnetic strip inside the gasket can't seal against the frame when the door is shut.

There is no effective way to repair the gasket.

Depending on the size and location of the crack, a refrigerator with a damaged gasket can use up to 50 percent more energy.

"This could increase your monthly electric bill by as much as five dollars," Walter said. "At this rate, you could recover the cost of a new seal in less than two years."

A leaky seal also can result in the accumulation of excess frost in the freezer compartment in the summer and the dehydration of refrigerated food in the winter.

Walter said replacement of a door gasket is not as simple as it may appear, so you should hire a qualified repair person.

"Since the gasket is part of the door structure, it must be installed precisely for the door to shut and seal properly."

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7. I am remodeling a home in the country and have the option of using propane or electric appliances. I am interested in conserving energy but also in saving money. Can you give me any guidelines on which form of energy might be best for my country home?

"I usually try to look at appliance fuel choices based on dollars per million Btu delivered," said Gene Meyer, extension mechanical engineer at Kansas State University. "The cost of the fuel, its Btu content, and the efficiency of the appliance all affect the cost per million Btu delivered."

Electricity prices vary from about 4 cents to 13 cents per kilowatt hour (kwh) while propane varies from a low of about $.50 to a high of over a dollar a gallon. Propane has 92,000 Btu per gallon and electricity has 3,413 Btu per kwh.

Use the following efficiency estimates for gas appliances.

Water heater           .62

Clothes dryer           .80

Stove                       .80

When computing the cost per million Btu for propane, use the following.

Cost per million Btu = Cost per gallon x 10.9 / efficiency.

"So, if propane costs $.80 per gallon and is being used for water heating, your cost would be $.80 x 10.9 /.62, which comes to $14.06 per million Btu," Meyer said.

Electricity use is very efficient, usually about 98 percent.

If you compute the cost per million Btu for electricity:

Cost per million = Cost per kwh x 293/ efficiency.

For electric water heating at $.07 per kwh, your cost would be $.07 x 293 / .98, which comes to $20.93 per million Btu.

Air and water-source heat pumps have much higher efficiencies and their cost of operation should be estimated using these techniques.

Meyer said there are other things you should consider in making your choice.

"You should not put a propane appliance in a room below grade," he said, "because propane is heavier than air and pools in low spots. Walkout basements may be OK, but regular basements are not.

"You also need to consider your personal preferences. I prefer to cook on a gas stove, but gas appliances often cost a bit more up front," he said.

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8. I generate a lot of used oil on my farm. What can I and other rural businesses do with large quantities of used oil?

"You have a few options for getting rid of used oil," said Sherry Davis, pollution prevention specialist at the Pollution Prevention Institute at Kansas State University. "The method you choose depends on a few factors, including how much oil you generate."

Farmers who generate less than 25 gallons of used oil a month are considered "do-it-yourself" oil changers and can give it to a service station or auto repair shop that burns used oil in a waste oil heater or recycles it, bring it to your local household hazardous waste facility with their permission, or send it for recycling.

Farmers generating more than 25 gallons of oil monthly and businesses that generate more than 55 pounds of hazardous waste monthly must recycle, reuse or send their used oil out for energy recovery. One of the easiest and most economical ways to get rid of used oil is to purchase a used oil space heater.

"A typical furnace generates 110,000 Btu of heat an hour from eight-tenths of a gallon of used oil," she said. "At this rate, the savings in normal fuel costs can pay for the oil heater within a year."

Heaters up to 500,000 Btu/hr in size can operate without special permitting.

Farmers and businesses can burn used oil generated at their own facility or from do-it-yourselfers without having the oil tested.

But, if you would like to take used oil from another business, you must have the oil tested to determine that it is "on-spec."

Used oil is considered on spec if it has a minimum flash point of 100 degrees Fahrenheit and meets specified concentration levels for total halogens and four heavy metals.

Acceptable oils for these furnaces include crankcase oil, transmission and hydraulic fluids. No hazardous waste solvents or other materials can be mixed with used oil burned for burning. Not only is it dangerous but it's also against the law — hazardous wastes must be recycled or disposed of in special treatment, storage and disposal facilities (TSD's) that will burn it for energy recovery.

If you would like our new fact sheet "The New 'Used Oil' Regulation" or free, nonregulatory, personal assistance on burning used oil in a space heater at your site, call Sherry Davis at 800-578-8898.

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Ask Energenie is produced by the Kansas Energy Extension Service through Kansas State University. This material was prepared with the support of the U.S. Department of Energy (DOE) Grant No. DE-FG48-97R802102. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily reflect the view of DOE.