Managing Interiors for Energy Control

Wanda Eubank and Patricia L. Snodgrass
Department of Environmental Design

Is it possible to control Mother Nature? Well, no, but we can control the amount of money we spend on the energy needed to keep the effects of her harsh winter winds and steaming summer sun out of our homes. How? By using certain elements and principles of design -- by managing our interiors.

Home energy bills can be greatly reduced with proper management. The first steps should include a thorough program of caulking, weather-stripping, insulating and managing the thermostat.

In this publication, we'll discuss ways to manage the interior home environment for greater physical and psychological comfort. Don't worry -- you won't have to refurbish your entire home. Many steps can be taken with the furnishings you already have or with little money invested. First we'll discuss technical terms and then discuss the easy changes you can make in your own home.

Comfort

Many factors, including air temperature and relative humidity, contribute to heat loss from the body and environment and thus effect our physical comfort.

Note
Psychological comfort refers to your personal response to colors, textures, furnishings, lighting and physical stimuli.

Heat flow

Before you can complete a management plan, you need to understand how heat moves. Heat moves in a predictable manner -- always to a cooler environment. This is a law of nature.

Conduction is the transfer of heat through a solid, the ability to conduct heat varies from material to material. Glass, metal, concrete and brick conduct heat well. Materials that resist conduction contain a high proportion of trapped air; they are called insulators. We measure insulating ability in R-value. The higher the value, the greater the reduction of heat flow. Window treatments and floor coverings can add insulation to walls and floors. Remember, R-values need to be considered both summer and winter because they slow both heat gain and heat loss.

Convection is the movement of heat through a liquid or gas. Convection occurs when air is heated, rises and pulls in colder air. Examples of natural convection are hot air rising above a radiator or warmer air currents moving up an open stairwell. Convection also occurs near windows, so a good management plan will include a way to stop convective losses here. In winter, warm air moves to the cool window glass and settles to the floor to make room for more warm air, which will then cool and settle to the floor. The cycle continues indefinitely unless you do something to stop it.

A closed-top window treatment stops air from circulating across the window glass. You can install something as simple as a cornice to control this unwanted circulation.

Radiation occurs when heat is transported through space away from a warm object to a colder one. The best example of this is the warmth gained from the sun on a clear day. The human body also radiates heat to cooler surfaces and objects. This potential heat loss can cause physical discomfort on a cold or cloudy day.

To combat discomfort, cover windows on cloudy or cold days and apply insulators to exterior walls. Use highly polished or shiny surfaces to reflect thermal radiation. Window treatment liners and wallpapers that incorporate foil or shiny materials will reflect some thermal radiation back into the room. This would also be effective behind a radiator.

Natural processes

Air infiltration is unwanted movement of air in or out of a building. When heat is lost from a building, the furnace must warm cooled air back to a comfortable temperature. Caulking and weather-stripping help reduce energy losses caused by infiltration. One source of infiltration often overlooked is electrical outlets on exterior walls. You can reduce infiltration with outlet gaskets. Plug unused sockets with plastic inserts. Use plastic inserts and outlet gaskets to reduce air infiltration in your electrical outlets. When you purchase these, be sure the package carries the UL labels for safety.

Evaporation occurs when body moisture is lost to the air by vaporization or absorption. Ceiling fans can aid in this process by creating air movement. This in turn creates a cooling effect as body moisture vaporizes (or evaporates) into the environment. In homes with high ceilings, the fans may be effective in circulating warm air trapped near the ceiling.

To keep a building from overheating, open it to the flow of outside cooler air. Your summer management plan should include a system for cooling and exhaust.

Before the common use of central heating and cooling systems, many people knew evaporation had a cooling effect. In the springtime, they covered furniture with fabrics like cotton, which absorbs heat and moisture and creates a cooling effect. In the winter, they removed the slipcovers and let the textured, nubby fabrics, which act as insulation, trap dead air.

The most natural form of energy is the sun. Its supply, while not endless, will certainly last a few more generations, and best of all, it's free!

Orientation, the direction your home faces, determines solar gain. North-facing rooms receive no direct sunlight and, in colder months, are always losing heat. Warm colors can psychologically compensate for the lack of sunshine.

East-facing rooms provide solar gain during the morning hours. In summer, these rooms are probably cool in late afternoon. Color can warm and brighten these rooms.

Family living areas facing south receive the most sunlight and tend to be the warmest in winter.

West-facing rooms absorb the most heat in the hottest time of the year. They also tend to be draftiest -- next to northern ones -- in winter.

Remember, once the sun gets in, so does the heat. For best results in the summer months, install materials that block the sun, such as solar screens, on the outside of the house.

Designed for comfort

Your energy management plan will depend on your lifestyle, your resources and your perception of comfort. There are individual differences in our perception of comfort. For example, the elderly and infants have special problems with temperature regulation due to defective or immature body control systems. To influence your physical as well as your psychological comfort, use these interior design devices.

Color

Certain "feelings" we derive from colors relate directly to energy. For example, colors that contain bright reds or yellows may remind us of candlelight, fire, sunshine or burning coals. These colors "warm" rooms exposed to cool northern light.

Colors that contain cool blue remind us of water, sky or ice. These colors may "cool" rooms exposed to southern and western sunlight.

No color scheme is absolutely "cool" or absolutely "warm." To make a cool color appear warmer (or a warm color appear cooler), place a different hue of the same color next to it. A pastel green will cool a warmer yellow green and blue violet may appear to warm a bright blue.

Identify the colors you use already as the first step in your interior design management plan. Highlight the "warm," dark colors in cold months and the "cool," pastel colors during the warm season.

Texture and pattern

Smooth surfaces like glass, plastic, high-gloss paint and mirrors look and feel cold. Textured surfaces, which can trap pockets of air, contribute to warmth. Placemats or tablecloths can warm smooth table tops. The larger the pattern, the more the design advances and the warmer it seems. Similarly, using small patterns, or no pattern, in a room will make it appear larger and cooler.

Floor coverings

All floor treatments have some value as insulation, and each can contribute to a different feeling in your scheme.

Sheet vinyl, tile or hard floor coverings provide less insulation value than carpet. Coverings with cushioned backing add an extra layer of insulation. Tile floors contribute to effective solar design, because they absorb daytime heat and radiate it to cooler nighttime air temperatures. Think about the room's use as well as the care and maintenance the floor covering will require. Cool, smooth flooring materials work best in areas where you want a cool feeling in the summer or in heavy traffic areas.

Carpeting insulates effectively against conductive heat loss in winter and heat gain in summer. Wall-to-wall carpeting provides the greatest amount of insulation. The denser the fibers and the thicker the carpet padding, the greater the insulating effect. The carpet's fiber surface traps warm air and makes it feel warm to the touch.
Area rugs can add both insulative value and psychological warmth to the room. If the dining room adjoins the living room, consider using coordinated area rugs to add warmth, color and continuity. On hard-surfaced floors, area rugs can add warmth in cooler months. Remove rugs or replace them with reed or fiber mats for a cooler look and feel in summer. Elderly residents, or those with impaired balance, may be at risk of falling if area or scatter rugs slip or bunch up.

Floor coverings with dark colors and dull finishes absorb the sun's rays more than light colored, shiny ones. Absorbed heat adds extra warmth as it radiates back into the room.

Window treatments

Windows can provide your home with solar heat, daylight and natural ventilation. However, because glass insulates poorly, windows also can be some of the greatest sources of home heat loss. If you don't have interior storm windows, installing them will reduce heat loss and heat gain from your windows by 50 percent. Interior storm windows also help control air infiltration.

When insulating windows, remember a number of layers will reduce heat loss because trapped air insulates. Drapery liners can form an additional layer. When properly installed, a roller shade can provide another effective layer. Mount the shade as close to the glass as possible while still overlapping the window frame.

Insulating window treatments have become increasingly available and affordable. They come in a variety of styles and patterns and often may be used under traditional window treatments. Some are available only through franchised dealers; others are best-suited to installation at the time the home is constructed.

Metal blinds are poor insulators because they are good heat conductors. Convective losses also occur at sides and between louvers. For the most part, metal blinds do not improve energy management. They do, however, effectively control solar gain, glare from daylight and ventilation.

The effectiveness of any well-designed insulated window treatment will depend greatly on how you manage the treatment itself. One must be willing to open and close any treatment according to the sun's position.

Walls

People tend to be uncomfortable when they sit, stand or lean on or near walls in cold weather. Walls are the largest surface in your house to be decorated. Using wall treatments that insulate, such as large textured wall hangings, will make a difference in the amount of energy needed for the occupants to feel comfortable. Wall covering liners can add insulation and slow infiltration.

Rough textures and irregular surfaces appear warmer than smooth surfaces. Flocked papers and grasscloth have surface textures that trap air and add insulative value.
Foil-backed papers radiate heat back into a room and prevent it from being conducted outside. Shiny mirror tiles, however, don't serve as radiators. Glass conducts heat while reflecting light and can give the room a cooler appearance.
Vapor barriers are often lacking in older homes. Just as heat seeks another environment, so does moisture. Moisture vapor migrates until it reaches a cold surface where it condenses into water. A properly installed vapor barrier prevents much indoor moisture from passing through to the insulation. This protects insulating materials from becoming wet, which would make them ineffective. Certain paints can be used under the decorative coat to create a vapor barrier. Just cover it with the interior paint or wallpaper of your choice.
Wall paneling is commonly used in homes. If you plan to panel a room, take advantage of the opportunity to add a layer of insulation or a vapor barrier first.

Note
Energy-efficient homes depend on solar orientation and adequate levels of insulation. Paneling, fabrics and paper are not a substitute for proper orientation and adequate insulation.

Furnishings

Color, texture, pattern and styling can contribute to the degree of warmth in a setting.

Some furnishings improve physical comfort in winter by helping to retain body heat. Closed-design furnishings such as wing-back chairs were initially designed to hold in heat radiated from a fireplace and to protect the occupant from drafts. Sofas and chairs with open styling promote heat loss. Recliners and ottomans keep feet off drafty floors. It is no accident that we associate wicker and rattan with tropical climates. Their open design promotes heat loss.

In the summer, use metal and wood furnishings -- they remain cool to the touch. In colder months, use floor-length tablecloths, pillows and chair coverings in warm colors. These items can also help trap air and slow heat movement.

Furniture arrangement is also important to your management plan. In summer, space pieces further apart to give an open,airy feeling and promote ventilation. Use only the pieces you need to prevent overcrowding. Bring furnishings closer together in winter to create a cozy arrangement. Place chairs and sofa closer together and near a heat source if possible.
Folding screens can reduce drafts around doors and seating arrangements. They also help define entryways and block cold outside air from flowing directly to the conversation area. Screens may also be useful for shielding large windows on cold and windy days.

If you have a choice, place large, heavy furniture pieces near exterior walls. You can insulate against winter cold and summer heat by placing a bookcase, hutch, chest of drawers, entertainment center or storage chest against exterior walls. One way to take advantage of solar heat is to put heavy, dark, bulky pieces near a window to absorb the sun's warmth. Keep in mind that upholstery and carpet fibers may eventually fade from being in contact with the sun.

Before you start rearranging your furniture, determine the natural traffic patterns from room to room and within each room. Analyze your family's activity pattern. Locate furnishings for passive activities, such as reading, studying, watching television or talking, near heat sources and away from windows and cold outside walls. You can locate furnishings for active functions, such as eating, working or playing, away from direct heat sources.

Lighting

Take advantage of wall and ceiling finishes
Light colors and shiny surfaces reflect more light than darker colors and dull surfaces.
Use daylight whenever possible.
Using task lighting above a work surface costs less than lighting the room with a ceiling fixture.
Install a dimmer switch to inexpensively control light levels. These switches save energy as well as change the mood of an environment by letting you adjust lighting to suit your needs.

Ideally, each light should be wired independently so that it can be turned on only as needed.

Manage your portable lamps for maximum efficiency. Placing a lamp in the corner of a room will increase efficiency by allowing the light to reflect from two walls. Three-way bulbs provide a choice -- low for television or conversation, medium for reading and high for detailed work like sewing or woodworking. Use translucent lampshades with white linings; opaque shades actually hold the light in and waste energy.
Keep your bulbs and fixtures clean. Dusty bulbs and light fixtures emit less light than clean ones. The dust also traps heat energy and shortens the bulb's life. Make it a habit to clean the bulb, shade and reflector.
Don't use higher-wattage bulbs than recommended
This shortens the life of the bulb. In addition, higher wattage bulbs may overheat, damage the fixtures and could cause a fire.
Buy the most light for your dollar
Wattage is a measure of energy used to light a bulb. Lumens measure light output. The more efficient the bulb, the more lumens per watt. Consider replacing the incandescent bulbs in your lamps with fluorescent lights. These last longer, produce less heat and give about five times as much light as incandescent bulbs. They do cost more initially, but they pay for themselves quickly.

Be aware that fluorescent lighting usually gives a "cool" coloring to a room. You may prefer the "warmth" of less efficient incandescent. Don't be tempted to save by purchasing longlife bulbs for your reading lamps. They will last longer, but they emit less light than a standard bulb. Use longlife bulbs in utility areas or hard-to-reach fixtures.

Lighting can help you manage interiors for a feeling of warmth or coolness. Incandescent lamps accentuate warm colors. Fluorescent tubes come in colors such as "deluxe cool white" for a cooler atmosphere or "deluxe warm white," which is closest to the warmer incandescent.

Accessories

Accessories stimulate us visually and provide insight into our personalities. The more things in a room, the more potential there is to trap air or absorb heat (but don't overdo; too many accessories can be overpowering).

In summer, unclutter
Create opportunities for heat to move quickly away from surfaces and furnishings. Plants bring the cool greenery of the outside to our living space. Mirrors and glass appear shiny and cool. Smooth fabrics conduct away body heat and are cool to the touch. Fresh flowers, light and airy in appearance, are a welcome sight.
In winter, use accessories to increase the R-value of exterior surfaces
Wall hangings provide decoration and insulation. Materials that trap air and provide texture can promote warmth in any location. Dried flowers, wooden candlesticks and candles are warm accents appreciated in the winter months.

Remember to use floor accessories. Large pieces seem to advance and take up space, which creates warmth. Plants are beneficial year-round, as they provide moisture for the room. This added moisture helps maintain indoor humidity at a comfortable level in the winter. Clay or tile pots look warm and actually absorb small amounts of heat.

Interior management, like exterior weathering, depends upon a cumulative effect. No action, by itself, will make a large impact.

Whether you're planning a major project or just looking for simple ways to cut energy costs, take time to think about the interior design factors and how they can affect your sense of comfort as well as your energy budget. This checklist will help you become more aware of interior design management techniques you can use to control the comfort level of your home.

As you look over the following list, ask yourself if these are ideas you already use, plan to use or that are not applicable.

Energy management techniques checklist

Color

Advance interior warm colors in winter.
Advance interior cool colors in summer.

Texture and pattern

Use smooth textures to promote feelings of coolness.
Use large patterns to occupy space and create warmth.

Floor coverings

Add area rugs to increase R-value and feeling of comfort.
Use flooring to absorb available sunlight where needed.

Window treatment

Use insulating window treatment to cut heat gain and heat loss.
Use solar screens to cut air conditioning load and costs.

Walls

Use a wall color that compensates for solar orientation.
Use a vapor barrier to protect insulating materials.

Furnishings

Rearrange furniture seasonally.
Use large or heavy pieces as insulators on exterior walls.

Lighting

Replace incandescent bulbs in portable lamps with fluorescent adapters.
Place light where needed for specific tasks.

Accessories

Use fewer and lighter accessories during hot summer months.
Add texture, color and pattern to increase feeling of warmth in winter.

GH2100, reviewed October 1993