This is a really interesting question because color plays a very important role in how warm any substance is, not just buildings. The paints that we use to cover our houses are made up of chemicals called pigments. It is a pigment’s job to absorb some light and reflect the rest. The darker a color of paint is (and the pigments that make up the paint) then the more light it will absorb rather than reflect. When a pigment absorbs light, it converts the light energy into heat energy which increases the temperature of the building. Putting these ideas together, darker paints will absorb more light and cause the building to heat up more.

Pigments are not just preset in paints but anything colored. You can test this idea for yourself! Try laying a white t-shirt and a black t-shirt outside on the ground on a sunny day. After a few hours go back and feel them both. Which one feels hotter? Here’s a hint: on a hot day, do you see more people wearing dark clothes or light clothes? Thank you for your question!

Well, light objects like white or objects that reflect a lot of light warm up more slowly in the hot sun. In contrast black objects reflect less light and hence absorb more sunlight energy and heat up faster.

Dark colors absorb light, which creates heat and heats the building. Light colors reflect light away. Dark colors also emit infrared light when there is no light shining, thus cooling the building off when it does not have light shining on it. Thus, a building that is black will heat up in the daytime and cool off at night, while a building that is white will remain cooler during the daytime but will not cool as much at night.

Much more important than color, however, is the greenhouse effect. Glass is opaque to infrared light but visible light will go right through it. This means that lots of windows let lots of light in, which heats the building, but then the heat can't escape back out the windows so easily, so the building will heat up.