Some simple considerations to protect windows from heat gain in summer can make your home more comfortable and reduce the costs of cooling your home.
Size and orientation
The size and orientation of your windows will affect the amount of sunlight entering your home. West, east and north-facing windows tend to be exposed to sunlight, while south-facing windows receive almost no direct sunlight. The orientation of your windows also influence how you use coverings and shading. Consider the orientation of your windows if you are planning a renovation.
Frames and glazing treatments
The strength of window frames, together with the glazing component, can greatly affect the energy efficiency of windows. The most energy efficient window frames are made from materials that won’t transfer heat and cold, such as timber, uPVC or combination frames.
Heat is both gained and lost from existing houses due to air leakage or draughts. Seal gaps around doors and windows to draught proof your home and save energy and money.
Coverings and shading
Large west, east and north-facing windows should be shaded for increased energy efficiency. External shading is much more effective at keeping your home cool than internal blinds or curtains, as it stops the heat reaching the glass, but using both external and internal window coverings will provide maximum protection.
How to shade windows for summer
The best way to shade your windows depends on which way they face, because the height and angle of the sun changes as it moves through the sky and as the seasons change.
Fixed horizontal shading devices, such as eaves and pergolas, are ideal for shading north-facing windows. If they are well designed, they can stop the high summer sun from hitting the glass, while still allowing the low-level winter sun to shine in and heat your home in winter. Some pergolas have louvres that can be adjusted to provide complete shading in summer, while still allowing the sun access in winter.
Adjustable external shading, such as blinds, awnings, roller-shutters and conventional shutters, are also suitable for shading north-facing windows in summer. The thicker and more opaque the material, the better the shading effect will be. The external shading should be adjustable to allow the sun in during the winter months and on cooler summer days.