This article was originally published in the September/October 1995 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.
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Home Energy Magazine Online September/October 1995
|Because most refrigerators reject heat from the bottom and/or back, they need adequate clearance to allow sufficient airflow. While no specific studies have been done to calculate the optimum clearance space, one general rule-of-thumb is to double the space recommended by manufacturers for refrigerator installation.|
The choices here will depend on the number of cooks, their cooking preferences, and whether or not the home is a candidate for fuel switching. Some people prefer cooking with gas, while others favor noncombustion appliances. Remodeling is the time to make the switch, since running gas pipes, vents, and electrical connections will influence the layout of the kitchen. Depending on the local gas and electric rates, energy savings can be significant, but the cost of switching should also be considered.
Almost all modern gas ranges save energy with electronic or thermal ignitors instead of standing pilot lights. The commercial ranges (new and used) that are becoming very popular in residential kitchens may not have electric ignition, so be sure to check before buying one. Self-cleaning ovens burn grime off the interior surfaces with a long, high-temperature cycle. While this uses extra energy, it reduces the need for caustic chemical oven cleaners. Self-cleaning ovens also have more insulation, which reduces energy use during normal oven operation. Beware of ovens with 400-watt thermal ignitors that operate continuously when the oven is on.
For electric ranges, the standard coil element is probably the best bet. High-tech ranges use halogen lamps or magnetic induction to heat the cooking surface. These are more efficient, but costly. Solid disk elements look better than electric coils, but they heat more slowly and generally use more energy.
Electric convection ovens cost about 30% less to operate than conventional electric ovens and are worth the extra investment. They circulate air inside the oven to improve efficiency and reduce cooking time.
Cooktops separated from ovens allow more flexibility for cooks than ranges. Energy use shouldn't be affected, but installing the individual units will require more resources and likely cost more money.
Microwave ovens are convenient and energy-efficient. They use one-third as much energy as conventional ovens and generate very little waste heat to burden the air conditioning system in the summer.
Choose a dishwasher with a built-in water-heating booster. About 80% of the energy used by dishwashers is for hot water, so using this booster heater means the temperature setting on the main water heater can be set at 120deg.F, instead of the 140deg.F recommended for dishwashing. The less water used, the less energy consumed, so check the manufacturer's data on water use and shop for models with variable wash cycles, including energy-saving cycles. Also, select an air dry option, which does not use the electric heater during the drying cycle (this is a standard feature on the latest models).
The kitchen has been declared the noisiest room in the house, and dishwashers are one of the reasons. Look for a dishwasher that is quiet as well as energy-efficient.
Small appliances don't use enough operating energy to worry about. In fact, using a small appliance may save energy compared to doing the same job with a big one. For example, heating a slice of pizza in a toaster oven uses less energy than firing up the full-size oven.
Efficient lighting starts with good design. Begin with task lighting for countertops and other work areas, then think about general background lighting. During the process, keep in mind how natural and electric light can blend for the best results.
Divide task light fixtures into independently switched task areas. For example, counter, island, range, and sink would each have a separate switch. With ample task lighting in kitchens, general ambient lighting may not be needed; however, if it is installed, it should also operate from its own switch. This background lighting could be a surface-mounted fixture, a cove light mounted on top of the cabinets, or a luminous ceiling. Recessed overhead lights, although used extensively in kitchens for both ambient and task lighting, can be the source of serious air infiltration and moisture problems and should be avoided when possible (see Recessed Downlights, p. 14).
Fluorescent or Incandescent?
Currently, fluorescents are the most efficient light source suitable for residential use. Since kitchen lights burn for hours at a time, they offer ideal applications for both linear and compact fluorescent lights. Not only do fluorescents use less energy, they also can last 10 times longer than incandescents, making them particularly appealing for difficult-to-reach fixtures.
Linear fluorescent lamps, commonly referred to as tubes, convert electricity to light with four times greater efficiency than the typical incandescent lamp. Tubes come in a variety of sizes. Larger ones work well for ambient lighting, while the smaller models are perfectly suited for under-the-cabinet task lighting, for example.
Compact fluorescent lamps (CFLs) are two to three times more efficient than incandescents. Their smaller size makes them easier to screw into sockets normally occupied by incandescents, but sometimes their unique shapes are not the perfect fit for fixtures. However, there are now many choices of CFLs on the market, especially for replacing 60W and 75W incandescents. Recently, manufacturers have introduced CFLs with light output similar to a 150W incandescent bulb. There are also CFL fixtures available that take pin-based compact fluorescents so there is no need to worry about the bulb's fit. Proper fit is particularly important in enclosed fixtures, where heat buildup can affect the lamp's performance. Favorite spots for CFLs in the kitchen are over the sink and in suspended and ceiling-mounted fixtures.
A fluorescent lamp needs a ballast to provide the proper electrical input. Select electronic rather than magnetic ballasts. They operate the lamp at a higher frequency, eliminating the flicker and hum sometimes associated with fluorescents. Older electronic ballasts have been known to interfere with electronic devices, such as telephones, televisions, and computers, but current models have eliminated this problem. See if the local electric utility can recommend any particular models.
Fluorescents once had a reputation for providing poor-quality light. That changed roughly 10 years ago when lamps with improved color characteristics became widely available. The color problem is easy to avoid by paying attention to two numbers. The first is color temperature, expressed in degrees Kelvin (K). Most people associate indoor light with the warm look of incandescent lamps at 3,000K or less. Fluorescents for indoor use should have a color temperature of not over 3,500K. The second number is the Color Rendering Index (CRI), which indicates how accurately the light displays colors. Always select lamps with a CRI above 80. Since each manufacturer has a different designation for color properties, it may be difficult to tell by looking at the packaging. However, the manufacturer's product literature often provides the CRI and color temperature information.
Only 10% of the electricity that enters an incandescent lamp comes out as light. The rest turns into heat, which must often be removed with air conditioning. Because they are so inefficient, incandescents should be used selectively for accent and task lighting, or dimming circuits where fluorescents might be too expensive.
Although they are up to 30% more efficient than other incandescents, halogen lamps are still less efficient than fluorescents. Their main advantage is a crisp white light and better control of the light beam. Halogen PAR lamps and the low voltage MR16 lamps are a good choice when you need to direct light to a certain spot.
Good lighting controls put the right amount of light in exactly the right place only when it is needed.
Dimmer switches reduce light output and energy use when not set at full brightness. As a practical matter, a dimming circuit should use an incandescent lamp. Halogen lamps can be a good choice because they are slightly more efficient than other incandescents. Although dimmers are available for some fluorescents, the ballasts and controls may be too expensive for most residential budgets.
Motion sensors, also known as occupancy sensors, are appropriate in areas such as closets and pantries, where people move in and out but may not stay long. Incandescent lamps work well with motion sensors. This kind of use will shorten the life of fluorescent lamps and ballasts.
|Recessed downlights are very popular in kitchens, but they can cause problems. Typical recessed fixtures create a large hole in the ceiling and allow a lot of air to pass from the room into the space above the ceiling. If that ceiling is insulated, trouble could be brewing.|
The first problem is heat loss carried by the air escaping from the kitchen. A second problem is a hitchhiker that goes along for the ride. Water vapor--generated in large amounts in kitchens--flows with the air through the recessed fixture and directly into the attic or wall cavity, where it can condense on a cool surface, such as the roof sheathing. This can lead to mold, mildew, and eventual structural decay. Cathedral ceilings are especially vulnerable to the moisture problem, because they have limited ventilation space.
To avoid these problems, consider surface-mounted fixtures, such as track lights. When recessed fixtures must be used, always specify airtight models that have been pressure tested for low air leakage and be certain they are properly insulated. To ensure the best efficiency and light distribution, install compact fluorescent fixtures.
Windows and Skylights
Adding windows captures natural light and saves energy. But don't go overboard. Too much natural light, especially if it's all from the same direction, can create glare. Large expanses of glass can also reduce thermal comfort by increasing heat gain or heat loss. So add each window for a specific reason: to frame a view, to light a task area, or for cross-ventilation.
The thermal performance of windows has improved greatly over the last 20 years. Today, multiple glazings, low-emissivity (low-e) coatings, and insulated edges combine to give windows overall insulating values that can exceed R-4. Window efficiency is rated by U-factor, which is the rate of heat flow (and the inverse of the R-value). A lower U-factor means less heat transfer.
If possible, install windows on the south side of the room. These will capture solar energy in the winter. Add overhangs and external shading to block unwanted heat gain in the summer. If external shading does not fit the project, look for new glazing products that block direct solar gain without the heavily tinted coatings needed in the past. The shading ability of a window is indicated by its solar heat gain coefficient. The lower the number, the better. Check the National Fenestration Rating Council (NFRC) labels on windows for the solar heat gain coefficient and U-value. The U-value on the NFRC label is the rating for the whole window, including the frame.
Small skylights can bring natural light to dark interior spaces without burning a single kilowatt-hour. However, they can also cause unwanted summer heat gain and lose warm air to the outside in winter. To minimize the problems, keep skylights small. Four to eight square feet may be all that's needed. In warmer climates place skylights on a north-facing roof plane to reduce summer heat gain.
If the existing structure allows, angle the walls of the skylight well so that they fan open into the room, allowing the light to spread. Don't forget to insulate the area around the skylight to at least the same R-value as the ceiling.
Whether illumination comes from a natural source or an electric lamp, try to take full advantage of it. Light-colored paint on the walls and ceiling will bounce light around a room. Prime locations are in skylight wells and on surfaces used for indirect lighting. Light colors also help to make a small room seem more spacious. Semigloss paint adds a bit of reflectivity and durability and eases cleaning. However, to reduce glare avoid semigloss on walls that receive direct sunlight.
Kitchens can get a bit steamy with all the cooking, dishwashing, and gathering of people in one space. In winter, the coldest surfaces in the kitchen are probably the windows and their frames. That's where the water vapor floating in the air will condense. Wood, vinyl, and fiberglass are the best frame materials for insulating value and for reducing moisture problems from mold and mildew.
Ten Common Energy Questions about Remodeling the Kitchen
1. What's the single most important efficiency improvement for my remodeled kitchen?
Make sure you have an efficient refrigerator.
2. What kind of lights should I specify?
Fluorescent for general lighting requirements and certain task-specific applications like under cabinets to light counter space. Incandescent, including halogen, for limited accent or task lighting and with dimmers where fluorescents are not available. (For general purposes, halogens are not much more efficient than other incandescants.)
3. I have lots of small appliances: toaster oven, coffee maker, etc. Are they major energy users?
No. Most small appliances that are used intermittently consume relatively small amounts of energy and sometimes are more efficient than using a larger appliance (like an oven).
4. Is it possible to get a dishwasher that will run quietly AND save energy?
Yes. Buy a new, euro-style dishwasher. Most of these units consume far less energy than models sold only a few years ago, and they are much quieter. You won't need to flee the kitchen every time you turn it on.
5. I decided to keep all my old appliances in the new kitchen. Does that mean I can't save any energy?
No. Make sure that your walls are adequately insulated and use fluorescent lighting. If replacing windows, install new, efficient models. (There are reversible ones for easy cleaning available).
6. I am basically just replacing the cabinets; what can I do to save energy?
You can reduce air infiltration by carefully sealing all utility cut-throughs and false ceilings before installing the new cabinets. Don't forget to leave space for ventilation around the refrigerator. Also, to save resources and money, you can simply reface the cabinet doors for an entirely new look.
7. I am considering buying a new, larger microwave oven. Is it less efficient than my oven and stove?
Microwave ovens will use much less energy than conventional stoves when cooking small amounts of food. That's a very common situation, so go ahead and buy it.
8. My old kitchen was very stuffy; what can I do to improve ventilation?
New, quiet exhaust fans are now available that allow you to hold a normal conversation while they work to remove moisture, odors, and gases from the area.
9. I want to increase the size of the kitchen. Does this mean I'll have to buy a higher capacity heating and cooling system?
Unless you are constructing a large addition, your present system will probably work since most heaters and air conditioners are oversized. But it is important to understand that comfort levels can change (and be improved) during a remodel. Be sure that proper air distribution and ventilation are considered in the new design.
10. Does cooking with gas or electricity make a difference in energy use? I'm trying to decide if I should switch.
Cooking with gas generally uses less energy, but some gas ovens have electric ignitors that stay on when the oven is on and should be avoided. Whether you will save money from switching depends on the rates you pay for electricity and gas. A gas oven uses about 0.112 therms per hour, while a standard electric oven uses about 2 kWh. So, if your rates were, say, 8¢/kWh for electricity and 60¢/therm for gas you'd pay about 16¢ an hour for the electric oven and 7¢ per hour for the gas oven.
If a kitchen is properly ventilated, moisture as well as odors and carbon monoxide vapors from combustion appliances can be controlled. Always install a range hood with at least a 150-cubic-feet-per-minute fan that exhausts to the outdoors. Avoid recirculating hoods because they do nothing to remove moisture.
Most range hoods are too noisy, so people don't use them as much as they should. One solution to the noise problem is a remote-mounted fan installed away from the kitchen and connected to the range hood by a duct 6 to 8 inches in diameter. Go ahead and pay more for a quiet fan. It will be used more because people will not have to leave the room to have a conversation.
Range hoods mounted above the cooking surface are effective because they work with the momentum of the vapors as they rise naturally from the cooking surface. Downdraft fans must overpower this natural momentum with a fan two or three times larger than is necessary in an overhead hood.
In tight houses or where multiple or larger exhaust fans are used, suction can cause flue gases to spill from combustion devices, such as gas water heaters, furnaces, and wood stoves. If the house has combustion appliances, be sure that they have an adequate air supply.
Insulation and Air Sealing
While working on the ventilation system, remember to seal the ducts and the openings where they penetrate walls. If old vents are not going to be used in the renovation, be sure they are sealed off and the area is insulated. Often flex duct is used to extend existing duct runs to a new register. It's important that there are no bends in the ducts that will inhibit air flow and that the joints are secured with airtight mechanical fasteners.
When the remodeling project tears into the building's structure, a whole new set of energy-saving opportunities arises. This is the perfect time to tighten up air leakage passageways that cause discomfort and contribute to high heating and cooling costs. While the walls are open, seal all the gaps around pipes and wires. Air leaks through gaps like these can be responsible for 30% of the heat loss in a typical older home; the kitchen, with all its plumbing, electrical, and gas penetrations, is a major source of that leakage. Don't forget the space behind cabinets and above false ceilings, which are common corridors for air flow to and from the outside.
Next, fill the walls, ceilings, and floors with as much insulating value as is economically feasible. The local utility will know what level is recommended for the area. An R-value may be printed on the insulation bag, but proper installation is required to actually achieve that value. Demand a high-quality job. Batt insulation should fill every nook and cranny without compressing the material. Loose-fill and dense-pack insulation can be blown into areas around obstructions. With both systems, the skill of the installer is critical. Use expanding foam to seal and insulate areas too small for fibrous insulation.
In most households, heating water ranks second only to space conditioning on the list of big energy users. Much of that hot water goes to the kitchen for cleaning and dishwashing.
As a first step to save energy be sure the thermostat on your water heater is not set above 120deg.F and that the tank is wrapped with an insulating jacket. Insulating the hot water pipes will save even more.
All new faucets should restrict water flow to no more than 2.5 gallons per minute. If a new faucet is not in the plan, a replacement aerator will reduce water use.
On-demand water heating systems installed in the kitchen eliminate the long wait for water to get hot as much of it pours down the drain. Until recently, most of these systems had drawbacks because of fluctuating temperatures, limited capacity and questionable energy savings. However, new demand systems, which simply accelerate the flow of water from the hot water tank and force standing water in the pipes back to the tank, provide convenience and save water and energy. Don't confuse these with constant recirculation systems, which increase energy use.
When most existing kitchens were designed, little thought was given to trash removal beyond garbage disposals and trash compactors. Now that household waste recycling is available in most communities, kitchens need to accommodate sorting and storage of an increasing number of materials. The kitchen is the logical place for a recycling center.
Recycling systems can be as individual as people and their kitchens. Any retailer with a good selection of storage supplies should be able to offer the makings of a suitable system. Here are two guiding principles:
- Keep it flexible. The recycling industry is growing and changing. Local recyclers may start accepting new materials or change the way materials are separated. A rigid storage system may not adapt to changes.
- Keep it simple. No one likes to deal with trash, so reduce handling to a minimum. Most people like a system that allows sorting, storage, and transportation all in the same container.
Green Building Materials
Throughout the project choose products and materials that are friendly to the environment. Hundreds of materials with recycled content are now available. They use less energy for reprocessing than new materials use for extraction and primary processing. A few examples are ceramic tiles made from glass bottles, floor boards resawn from old barn beams, and cellulose insulation that gives a second life to newspapers.
Other categories of green materials are wood from trees that are grown in sustainably managed forests and nontoxic products for sealing, finishing, etc. A few large cities have stores that specialize in these products. Several sources of information about sustainable products are listed under Resources.
Consumer Guide to Home Energy Savings, American Council for an Energy-Efficient Economy, 2140 Shattuck Ave., Suite 202, Berkeley, CA 94704. Tel:(510)549-9914; Fax:(510)549-9984. (Includes guide to efficient new appliances)
Environmental Building News, West River Communications Inc., RR 1 Box 161, Brattleboro, VT 05301 Tel:(802)257-7300; Fax:(802)257-7304. (Bimonthly newsletter on sustainable building)
Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180-3590. Tel:(518)276-8716; Fax:(518)276-2999. (Books, including Lighting Pattern Book for Homes, and technical reports on energy-efficient lighting)
The Smart Kitchen, and Choose to Reuse, Nikki and David Goldbeck, Ceres Press, P.O. Box 87, Woodstock, NY 12498. Tel/Fax:(914) 679-5573.
Iris Communications, Inc., 258 East 10th Ave., Suite E, Eugene, OR 97401. Tel:(800)346-0104; Fax:(503)484-1645. (Books, videos, product directories and databases on energy efficient and sustainable building materials, free catalog)
Center for Resourceful Building Technology, PO Box 100, Missoula, MT 59806. Tel:(406)549-7678; Fax:(406)549-4100. (Sustainable building consulting, product guides)
|Bruce Sullivan is president of Iris Communications, Inc. and editor of Energy Source Builder.|
|This article is part of a series on energy-efficient remodeling, which is being funded by the Environmental Protection Agency and the Department of Energy.|
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