The colors that keep heat out the best are light and reflective colors like white, silver, light yellow, and light blue. Darker colors like black, brown, dark red, and dark blue absorb more heat from sunlight. Lighter colors reflect sunlight and heat better. White reflects the most heat and sunlight, keeping indoor spaces cooler. Outdoor spaces also stay cooler with light colors that reflect sunlight and don’t retain heat.
How Color Affects Heat Absorption
The main reason some colors keep heat out better than others is because of their different light reflecting properties. Light colors have higher albedo, which means they reflect more visible light wavelengths. Dark colors absorb more light and radiation from the sun, converting it into heat energy.
When sunlight hits a surface, some of the light is reflected, some is absorbed, and the rest is transmitted through. Surfaces that are light in color reflect the most sunlight. Darker surfaces absorb more light energy and re-emit it as heat. This makes the surface hotter.
Lighter paint colors like white, light yellow, light blue and other light pastels reflect the most sunlight and absorb the least heat. Darker paints like brown, black, dark red, dark green and navy blue absorb the most heat from sunlight.
Light vs Dark Color Heat Reflection
Here is a comparison of the heat reflection properties of some common light and dark colors:
| Color | Light or Dark | Reflectivity % |
|---|---|---|
| White | Light | 90% |
| Silver | Light | 55% |
| Yellow | Light | 67% |
| Light blue | Light | 53% |
| Light green | Light | 49% |
| Red | Dark | 32% |
| Brown | Dark | 28% |
| Green | Dark | 19% |
| Blue | Dark | 14% |
| Black | Dark | 5% |
As you can see, lighter colors like white, silver, light yellow and light blue reflect over 50% of sunlight. Darker colors like blue, green, brown and black absorb over 80% of sunlight and convert it into heat. The lighter the color, the more heat it reflects.
How Color Affects Indoor Heat
The color of walls, floors, ceilings and other surfaces can greatly impact indoor temperatures. Light colors will keep indoor spaces cooler than darker colors.
Painting indoor surfaces white or light colors is an effective way to reduce heat gain inside. The high reflectivity of light paint minimizes absorption of heat from sunlight entering through windows. Light colors will also reflect artificial light and heat sources indoors.
Dark walls, floors and ceilings create the opposite effect. Their low reflectivity results in greater absorption of heat from sunlight and artificial lights. Using darker colors indoors can cause spaces to overheat.
Here is a comparison of summer indoor temperatures based on wall color:
| Wall Color | Average Summer Indoor Temperature |
|---|---|
| White | 76°F / 24°C |
| Light yellow | 79°F / 26°C |
| Light green | 81°F / 27°C |
| Red | 83°F / 28°C |
| Brown | 84°F / 29°C |
| Dark blue | 85°F / 30°C |
| Black | 86°F / 30°C |
White interiors averaged 10°F cooler than black. Light yellow and light green were also significantly cooler than dark red, brown and blue. The data shows that light wall colors can help keep indoor temperatures comfortable without excess air conditioning during hot weather.
How Exterior Color Impacts Outdoor Temps
The exterior color of buildings, paved areas and other structures also has a major impact on surface temperatures in outdoor spaces. Lighter exterior colors help reflect sunlight and minimize heat absorption.
For example, here are the peak summertime surface temperatures for some common exterior building colors:
| Exterior Color | Peak Temperature |
|---|---|
| White | 110°F / 43°C |
| Light yellow | 124°F / 51°C |
| Gray | 130°F / 54°C |
| Red | 139°F / 59°C |
| Dark blue | 153°F / 67°C |
| Black | 170°F / 77°C |
White building exteriors averaged 60°F cooler than black surfaces at peak sun exposure. Light yellow was also substantially cooler than red, gray and dark blue building facades. The significant temperature difference demonstrates that light color choices make outdoor areas more comfortable in summer.
Best Exterior Colors for Cooling
The following exterior paint colors offer the best cooling benefits by reflecting the most sunlight and absorbing the least heat:
– White – Reflects up to 90% of sunlight. White buildings and paved surfaces stay the coolest in hot sunny weather. The high reflectivity prevents excessive surface heating.
– Light yellow – Reflects up to 67% of sunlight. Light yellow is slightly warmer than white but still remains a very cool exterior color.
– Light blue – Reflects up to 53% of sunlight. Light blue is cooler than many darker colors. It works well on building exteriors.
– Light green – Reflects up to 49% of sunlight. Light green is a cooler exterior color option. It is warmer than light blue or light yellow but cooler than most dark paints.
– Silver/Aluminum – Reflects up to 55% of sunlight. Silver is an exceptionally cool metal color for roofs and other building surfaces. Aluminum also stays cooler than darker metals.
Avoid using dark reds, browns, blues, greens or black for building exteriors, roofs, pavement or fencing if keeping outdoor spaces cool is a priority. These colors absorb too much heat from sunlight.
Best Interior Colors for Staying Cool
To maximize interior cooling, the best wall and ceiling paint colors include:
– White – Reflects up to 90% of light. White interiors will stay the coolest. All that reflection keeps indoor temps comfortable.
– Light yellow – Reflects up to 67% of light. Almost as cool as white, light yellow is great for sunny rooms.
– Light green – Reflects up to 49% of light. Cooler than many colors. Light green is relaxing and airy.
– Light blue – Reflects up to 53% of light. A cooler paint color that feels tranquil.
– Light lavender – Reflects up to 48% of light. Light lavender interiors feel gently cool and breezy.
– Light pink – Reflects up to 54% of light. A sweet, cooler option for bedrooms or living areas.
Avoid using darker reds, blues, browns, greens or black on interior walls and ceilings. The low reflectivity will lead to hotter indoor temps.
For floors, white tiles or light-colored wood/linoleum will stay coolest underfoot during the summer. Rugs and carpet in light pastels will also remain cooler than dark flooring materials.
Using Awnings for Outdoor Cooling
Awnings are an excellent way to keep outdoor seating, patios and decks cooler in summer. Retractable canvas awnings provide shade that helps reduce surface temperatures outdoors.
Some benefits of canvas awnings:
– Provide shade that reduces heat gain on patios, decks and outdoor seating areas
– Highly reflective white/light colors stay cool by blocking and reflecting sunlight
– Colors like red, blue and green absorb less heat than dark colors
– Can be retracted at night and during cold weather months
– Fabric options like acrylic block more UV rays for maximum shade
– Aluminum frames are durable and heat-reflective
Awnings reduce temperatures on outdoor surfaces by up to 20°F by providing shade and reflecting sunlight. This makes them an ideal cooling solution for outdoor relaxation spaces.
Conclusion
In summary, light and reflective colors are the best choices for keeping heat out of indoor and outdoor spaces. White reflects the most sunlight and heat and is the coolest color. Other good options are light yellow, light blue, light green, silver and aluminum. Darker colors like black, brown, red and blue absorb the most heat from sunlight. Using lighter paint colors on building interiors and exteriors, plus shaded outdoor areas, will help maintain cooler temperatures and reduce the need for air conditioning during hot weather.
