State University Extension
Home Maintenance And Repair - 01500594
Energy Efficient Interior Design
Energy-conscious interior design is the designing and planning of rooms
and specification of materials with the goal of reducing energy
consumption in a home. Energy- conscious occupants focus on ways to
make their homes thermally comfortable while reducing energy
consumption. Energy-conscious design combines conservation methods,
such as insulation and thermostat set-back, with passive solar heating.
This design approach can be applied to both newly built homes and older
homes. It involves first making the home as energy conserving as
possible, then supplying the remaining heating needs with solar heat by
increasing the number of windows on the south side to collect heat (and
possibly reducing the number of windows on the north and west sides),
using thermal mass to store heat, and properly designing and placing
walls and furnishings to allow distribution of heat.
Storage of solar heat occurs in a dense mass material such as concrete,
brick or water. Most mass materials are hard surfaces that reflect
sound. Combining the hard thermal mass with a large expanse of window
glass gives you many sound-reflecting surfaces. Therefore, if not
absorbed by proper materials, noise can become a problem. Furniture
design should enhance air circulation, and furniture placement should
allow maximum exposure of the thermal mass to the sun.
The lightness or darkness of a color affects whether it can absorb or
reflect heat and light. Generally, light values---tints of a hue such
as beige, pink or cream--- are used to reflect heat from a lightweight
thermal mass, such as furniture or ceilings, to a more efficient mass
that stores the heat, such as a brick wall. The use of light values to
reflect heat can be balanced by dark value colors on the thermal mass.
The color used in a room can make you feel warmer or cooler. Generally,
reds, oranges and yellows are considered warm colors. These would be
used where the actual room temperature is cooler, such as on the north
side of the house where there is no direct sunlight. The cool greens,
blues and violets should be used in rooms with southern or even western
The thermal mass added to a house enables the solar heating system to
work properly. Mass, in the form of a dense material, absorbs heat
during the daytime to prevent overheating. lt then stores the heat
until the air temperature of the room drops when the sun goes down.Then
the heat is naturally released from the mass material, warming the
interior throughout the cool night.This same natural process occurs in
the passive solar home, except that the heat is trapped by the walls or
floors of the house and used to warm its occupants. (insulation is
closed across the windows at night to keep the heat inside.)
A mass material's effectiveness is measured by its ability to absorb
sunlight, conduct surface heat into its mass and hold the resulting
heat. Mass materials vary greatly in the amount of heat they retain.
Frequently, older structures are not designed to support the weight of
additional thermal mass. Lightweight, efficient mass is suggested for
many installations. Following is a table showing the percentage of heat
retained by various mass materials.
The percentage absorption varies according to material, color, and
finish or texture. The best thermal mass materials would seem to have a
dark-colored, rough, matte surface.
Of equal importance is the need to place furniture so that it shades
the mass floor or wall as little as possible. The general rule of thumb
is to shade less than 30 percent. This will still allow maximum
effectiveness for heat absorption and release. The furniture also
should be raised off the floor slightly so air can circulate. This
means no wall-to-wall carpeting; no large sectional sofa; no skirted
sofas that shade mass floors; no bookcases on mass walls; and no
secretaries or armoires on mass walls.
Fine tuning your energy-conscious interior design will take some
effort, but it will allow you to reduce energy consumption without
losing design quality. Here is a list of additional energy conservation
measures that are possible through appropriate interior design:
1. Covering walls with fabric, gathered on a rod top and bottom (be
sure to flame-proof the fabric).
2. Using closets as buffers on north or west walls.
3. Adding a heat lamp to a bathroom to take the chill off on cold
4. Using thermal wallpaper to insulate, foil wallpaper to reflect heat
back into the interior.
5. Using filled bookcases on outside, non-mass walls to act as
6. Using large decorative area rugs, tapestries or fabric wall hangings
on outside, non-mass walls to add insulation.
7. Using carpet and a good pad to reduce heat transfer through floors,
in addition to keeping bare feet warm.
8. Using high-back, overstuffed furniture in northern rooms to reduce
drafts and allow one to become engulfed (snuggle) in the chair.
9. Using furniture with skirts where drafts need to be avoided.
10. Using a reversible ceiling fan to pull the air up in the winter to
circulate the warm ceiling-level air without any draft on the occupant
(particularly those fans placed directly over a seating area). Then
reverse it for summer so the air flows across an occupant, cooling by
Here is a list of products and where to find them to help conserve
1. Movable insulation: designed to cover and insulate windows on the
interior; can be found at fabric stores, energy stores, drapery shops
and some lumber yards.
2. Mini-blinds: used to reflect sunlight and focus daylight; can be
found in most department or drapery stores.
3. lnsulated decorative ceiling tiles: added to the ceilings as
insulation; can be found in lumber yards and energy stores.
4. Thermal wallpaper: used to add insulation to outside walls; can be
found in energy stores, lumber yards and some wallpaper stores.
5. Vinyl wallpaper: used as a vapor barrier on outside walls; found in
6. Patterned and dyed concrete floors: used as a thermal mass, cheaper
than tile floor and aesthetically pleasing; inquire of local
7. Area rugs: used on north walls to insulate, in buffer areas to
insulate or add psychological warmth; can be found in department and
8. Quarry tile, ceramic tile, brick veneer or paving brick: used as a
decorative treatment and additional mass over the thermal mass floor or
wall; can be found at building supply firms and some lumber yards.
9. Fluorescent lighting fixtures: used to replace some incandescent
fixtures, especially in bathrooms, kitchens and utility rooms; can be
found in electrical and lighting supply stores.
10. Other energy-conscious design products can be found in energy
stores or order the Solar Age Resource Book, Everest House, 1133 Avenue
of the Americas, New York, NY 10019.
This information comes from Michigan State University Extension
bulletin E-1771, Energy-Conscious Interior Design.
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This information is for
educational purposes only. References to commercial products or trade
names does not imply endorsement by MSU Extension or bias against those
not mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU Extension.
Reprinting cannot be used to endorse or advertise a commercial product
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employer. Michigan State University Extension programs and materials
are open to all without regard to race, color, national origin, gender,
gender identity, religion, age, height, weight, disability, political
beliefs, sexual orientation, marital status, family status or veteran
status. Issued in furtherance of MSU Extension work, acts of May 8 and
June 30, 1914, in cooperation with the U.S. Department of Agriculture.
Thomas G. Coon, Director, MSU Extension, East Lansing,MI 48824. This
information is for educational purposes only. Reference to commercial
products or trade names does not imply endorsement by MSU Extension or
bias against those not mentioned.
information.was reviewed as
of June 2008. For more information about the contents please
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