CHAPTER 21 I PASSIVE DESIGN Solar gain


Solar gain (also called solar heat gain) is a term used to describe the increase in temperature in a space or material that results from solar radiation.


The amount of solar gain increases with the strength of the sun, and with the ability of the material to absorb the radiation. Dark-coloured, rough-textured objects absorb solar radiant energy more readily than light-coloured, shiny objects. When an object is struck by sunlight it absorbs the solar energy (i.e. visible light plus a small amount of ultraviolet light) from the sunlight and later radiates this energy as infrared radiation.


When this happens in a building with low-e glazing the glass traps the energy (i.e. infrared radiation) inside. This is essentially the greenhouse effect. The application of low-emissivity coatings to the glazing makes the glass transparent to the visible light but not to the infrared radiation.


thermal radiation (e.g. infrared)


solar energy (i.e. visible light)


 KEY PRINCIPLES


Homes designed to optimise solar gain have three features:      


 


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