Did you know that 20 – 30% of the energy bill of a household is because of improper use of windows and glass doors? In winter they let the heat out of your house so your heating system must continually work in order to keep the temperature of your house constant. During the summer they let heat inside your house so your air-conditioning system must work much harder to cool your house.
The following tips can help you save some of your energy bill:
- If you have single glazed windows, replace then with high performance double glazed windows. In very cold climates, in order to reduce the heat loss and keep heat in, prefer gas-filled windows with low e-coatings. They will reflect the heat back into the room. In warm climates, in order to reduce heat gain, prefer spectrally selective coating windows. They will reflect some sunlight on the outside, preventing all the heat from entering the house.
- In the summer use shades and blinds in order to prevent the sunlight from entering the house. During the winter use curtains in order prevent the draft from the windows to enter the house. When there is sunlight in winter open them to allow some heat to warm up the room.
- Install storm windows either on the inside or the outside of your windows. They will add another layer of protection particularly if you have leaky or single-pane windows.
- Repair your existing windows and storm windows, if necessary
- In US, when installing new windows or replacing existing ones prefer the ENERGY STAR® label. ENERGY STAR is a US government program that ensures that products follow strict energy efficiency guidelines and helping us to protect the environment.
- Prefer windows with low rate of heat loss (U-factor), which provide greater resistance to the flow of heat and provide better insulation to the house. Good double glazed windows have U-factors less than 0,3 while good triple glazed windows can have U-factor of 0.15. Different U-factors can be preferred depending on the climate where you live. ENERGY STAR provides guidelines for suitable U-factor for your climate.
- Prefer a low SHGC (Solar Heat Gain Coefficient), which controls the amount of solar radiation that will pass through your window. Prefer windows with low SHGC. Again ENERGY STAR provides guidelines for suitable SHGC for your climate.
- Take into account the orientation and shading of your house and of the windows before selecting your preferred type of window.
- In warm climates install exterior shading (e.g. shutters, awnings, tree shades etc) that will block the radiation of the sun before it reaches the window.