Solar homes are a versatile and a great way of making your home sustainable by producing energy using renewable sources. Not only they use a renewable power source but also they are a one-time investment which requires low maintenance and gives high performance if implemented in the correct manner.
The color of these solar homes is an important aspect as the amount of heat absorbed or emitted is affected by the color the house is painted in. The color varies for the different walls depending on the direction they face as well as the climatic conditions of the region.
Therefore for proper working of solar homes, color is an important feature deciding the efficiency of the homes. The color determines the absorbance and the emittance coefficient which in turn determines the amount of heat that can be used for the generation of power.
With the requirement of solar homes being in summer and winters, color has to be such that there is optimum absorption and emission.
Color Requirement of Solar Homes
Before going into further details, lets understand two important terms used frequently in solar home color considerations – Absorption coefficient and emissivity. Absorption coefficient is a parameter which helps in determining the amount of absorption of sunlight and emissivity shows the emitting power of the surface.
Shades of Black have absorption coefficient around 1 and shades of white has the emissivity of around 1. Lighter colors tend to be having lesser absorption and more emission than the darker colors. Absorption and emission both go hand in hand, more the absorption lesser the emission and vice versa.
As the house should emit maximum heat in the summer and absorb heat in the winters, therefore shades of both the colors are important for the building of the house.
Thus for having the best possible design the walls need to be colored by the right shades depending on the right direction. South facing walls should have shades of black as their colors as they have maximum absorption and can thus help in tapping the solar energy in winters. East and West walls should be colored white for having maximum emission of summer sun.
Options available :
Source: Book titled, Solar Technology for Buildings bu Ursula Eicker
The above diagram shows major paint colors that can be applied to the south facing walls for absorption purposes.
Colors like black and white have to be used together. Therefore both white plaster as well as galvanized steel is good options.
The above chart conveys the major colors which are having a good emissivity. All the above colors can be preferred according to the users’ needs and demands as well as the local climate.
Solar home implementation has to be done with care and with due consideration of all important parameters, including color. With proper architecture solar homes can be very productive as a power source.
For having optimum productivity, solar homes should have the right color as well as the shape, orientation and basic architecture. The right color is determined according to various aspects like the color’s absorption coefficient, emissivity, local factors like climate, fog as well as the shapes and orientations coupled with it.