Heat moves through each of these elements, into the building in the summer and out of it in the winter. The higher the temperature difference the greater the flow of heat. Many projects focus on this principle of building design as a cheap, effective way to lower energy consumption. Instruct staff to lower blinds and close curtains in the summer Windows have the lowest insulation value of any element of the building envelope. They also permit radiant energy to enter a space, as opposed to conduction through the walls and roof.
Thermal radiation accounts for a large portion of the energy in natural sunlight.
Closing curtains or blinds will reduce the radiant contribution of the light and also reduce the conduction of thermal energy through the window. An air space is created between the blinds and the window that, since air is an outstanding insulator, increases the resistance to heat flow. Double pane windows take advantage of this same premise by trapping an air pocket between the panes. This enhances thermal performance. In the heating season the opposite applies.