Windows provide the weak spots in your home as far as energy efficiency goes. As the summer weather heats up, the windows will account for up to 87 per cent of the heat gain that your home will experience. The windows are also inefficient in winter, allowing up to 49 per cent of your home's warmth to exit. The net effect of this is that your house will be less comfortable, and you'll pay via energy costs, as your air conditioning or heating bills escalate needlessly. 

You aren't helpless against this onslaught, however, as you can install specific types of glass that hinder heat transfer. Two options are explained below.

Low-E Glass

Low-E glass has a microscopic, invisible metallic coating that deflects heat. This type of glass reflects solar radiation from entering rooms via windows and making them hotter, and it also deflects winter warmth back into rooms in winter, helping you warm inside spaces. 

In attempting to make your home more energy-efficient, you don't need to go with a broad brush or one-size-fits-all strategy. Suppose, for example, that you live in a cold southern region of Australia. In that case, you might want your home to benefit from the free warmth provided by the sun shining through your windows and prefer to install double glazed windows or fix low-E glass only on west-facing windows that receive afternoon sunlight. Your glass contractor can advise you on the best strategy for your local climate and house orientation.

Double Glazing and Low-E Glass

No matter what kind of climate you live in, you'll benefit from double glazed windows. These units consist of two panes with space in between, either filled with air or inert gas. Thus, heat can't so quickly jump through the barrier. Gas is less heat-conductive than air and therefore is ultra-efficient. With an air-filled pocket, the hot air will rise so that the upper part of the window becomes warmer than the lower part. 

You can use low-E glass within a double glazed unit to make it more efficient still. Where you position the low-E pane, though, depends on your primary concern. If you mainly want to keep warmth inside, the coating should be on the inner pane, facing outdoors. If, on the other hand, you want to deflect solar radiation and keep rooms cool, the low-E coat should be on the outer pane, facing towards the room.

By installing energy-efficient residential glass windows, you'll block a massive amount of heat from either exiting or entering your home. You'll need to decide whether your priority is to keep your home cool, as it will be in hot climates, or whether you want to make your home warmer against a chilly winter. You also need to take the window orientation into account.