Window technology has come a long way, and a new set of windows for your new home or remodelling project can enhance the look of your home while improving its energy efficiency.

Choosing The Perfect Window Size For Your Wall

There are many factors to consider when choosing the right windows for your home, including how much wall space they will occupy. Window size hugely impacts the energy efficiency of a room. Large expanses of regular, clear-glazed windows can make your rooms uncomfortably hot during summer and hard to warm during winter.

The perfect window size can be determined by two key factors:

  1. Building orientation

    In the northern hemisphere, the sun is oriented towards the south for most months of the year. In order to benefit from the winter sun, consider placing larger windows to the south. During summer, the sun is usually at a higher angle in the sky, so south-facing windows can be easily shaded with awnings and eaves.

    North-facing windows won’t receive any direct sunlight in winter, but they will get some in the early morning and late afternoon during summer. You should keep north facing windows small to cut down heat lost during cooler months, and minimise heat gain during summer.

    The east and west oriented windows receive minimal sunlight during winter, spring, and autumn, but excessive sunlight during summer. As such, these windows should be small with proper shade to reduce extremely hot room temperatures during summer, and to reduce important heat from escaping in winter.

  2. Amount of thermal mass in the internal building materials

    Thermal mass refers to the ability of a material to take in (absorb) heat energy. To change the temperature of a high density material such as tile, brick, or concrete, you require a lot of heat energy. As such, these materials are classified as high thermal mass materials. Timber and other lightweight materials, on the other hand, have low thermal mass.

    Proper application of thermal mass around your home and rooms can make a huge difference to comfort, as well as your heating and cooling costs. Larger areas of windows or glass are best suited to homes built with materials of higher thermal mass, and for homes with larger south-facing windows. Homes built with materials of less thermal mass should try to reduce large areas of regular glass.

    For instance, for south facing windows, homes built with concrete slab can have windows occupying up to 25 percent of the total individual room floor area. Those built with timber require up to 20 percent of the room’s floor area, while those with poor access require less than 15 percent of the room floor area.

Generally, the size of your windows should be considered based on accurate elevations of your rooms drawn to scale, so you can try different sizes and see what looks right.