April 14, 2017
There are two ways to heat and cool your home — the mechanical way (active) or the non-mechanical way (passive). Most homes utilize both.
Passive heating and cooling strategies are the least expensive in terms of both financial and environmental costs. Celebrate Earth Day and reduce your utility bills and carbon footprint with these passive heating and cooling window strategies!
Passive heating and cooling refers to strategic uses of sun, orientation, insulation, ventilation, windows, shade, and trees in order to produce a desired temperature and comfort level in indoor spaces.
Although homes today are more energy-efficient than ever, many houses miss out on a lot of energy-saving opportunities. Passive heating and cooling simply refers to maximizing these opportunities.
Many passive heating and cooling strategies depend on the energy-efficient design of the building, but you might be surprised to learn all the basic ways you can supplement your heating and cooling system with things like air movement, shade, and insulation.
About 40% of unwanted heat that enters the home comes through your windows, making them the number one source of heat gain. Windows are also notorious for air leaks and poor insulation.
Replacing windows with high-quality storm windows can cost thousands of dollars. Relocating windows to take more advantage of solar heat gain and passive cooling is also very expensive. Fortunately, there are other ways you can increase home comfort and lower energy bills.
Learn how to make your windows energy producers, not energy liabilities.
Weatherize your windows with caulk and weatherstripping. You can check to see if you have air leaks around your windows with a lit incense stick or a thin piece of toilet paper.
Slowly trace the smoke or paper around the perimeter of the window to see if it begins to move erratically. If you see the smoke or paper move, you have an air leak that should be sealed.
Sealing your windows helps protect your home from summer heat and winter cold. It also helps keep your conditioned air inside the home. Outside air can infiltrate your home in many areas besides your windows, such as doors, walls, and where utilities enter the building.
Learn more about finding and sealing air leaks around the home.
In order to reflect heat away from the home, it’s recommended that you apply reflective window coatings or solar screens. These products can be purchased at your local home improvement store. Not only do they reduce cooling costs, but they’ll also cut down on glare and reduce sun damage to furniture, paintings, and other objects in your home.
There are two main types of window screens: sun control films and combination films.
Sun control films reflect as much as 90% of the incoming sunlight, but they also reduce light transmission, darkening the room.
Combination films are best for homes that have hot and cold seasons. They will reflect solar heat away from the home while allowing some light in. They also work to keep conditioned heat from escaping out the windows.
Avoid placing windows screens on south-facing windows if you want to take advantage of the heat gain during winter. If you can, remove the solar screens during colder weather to take full advantage of the sun.
Low-emissivity (low-e) window glazing can also be used to make your windows more energy efficient. It’s worth considering, but make sure you consult with a professional first. You may want heat-rejecting glazing on west windows, high R-value glazing on north and east windows, and clear double-glazing for solar glazing.
One great way to block unwanted heat from the sun is with strategic shading. You can use overhangs, louvers, vertical fins, shutter, trees, and plants.
Exterior shades block the sunlight before they enter windows, making them more effective. When choosing your exterior shading, keep in mind that you will probably have to remove them during cold seasons and put them up during hot seasons. This helps protect them from damage and allows you to take advantage of winter heat gain.
For exterior shading, consider awnings, louvers, shutters, rolling shutters, shades, and solar screens. Awnings can reduce your heat gain by around 60-70%. If you choose to install awnings, choose a lighter color so it can do double duty by reflecting the sun rays. Also, make sure there is a gap between the awning and the side of the house to help vent accumulated heat.
Shading your home can reduce your indoor temperatures by as much as 20 degrees. Start with the windows that receive the most sunlight. Learn how to shade your home with trees.
While interior shading isn’t as effective as exterior shading, it is still worthwhile to block the sun rays from inside your home.
Drapes are probably the best for interior shading. Choose light-colored fabrics and try to get them as close to the wall/window as you can. The tighter the drapes or curtains are to your window, the more effective they are at preventing solar heat gain.
Venetian blinds aren’t as effective as draperies and curtains, but they do allow you to let some light and air in while reflecting the sun’s rays.
Roller shades can do a great job reflecting the sunlight away from your home, but they have to be fully drawn. This blocks the natural light considerably and restricts airflow.
It may seem obvious, but open blinds and curtains when the sun is out and you are in need of heat and close them when you are trying to keep the heat inside the home.
When possible, your home should be designed to have a proper amount of insulation and ventilation. This means that windows should be located on opposite sides of each other.
Natural ventilation improves indoor air quality and helps keep homes cool and comfortable.
If you have ventilation problems, a whole-house fan is a good idea. Ask your local HVAC technician about whole-house fans and how they can work with your thermostat and HVAC system.
While natural ventilation and whole-house fans are effective at removing unwanted heat, they aren’t great at moving air. Ceiling fans, on the other hand, are a great way to create a breeze and feel cooler. Learn how to choose the right ceiling fan.
Well-placed trees and plants can help shade your home, block strong winds, and add beauty and value to your property. When planting trees around your home, choose native plants that lose their leaves in the fall (deciduous) so you can cut cooling costs in the spring and summer while allowing sunlight to hit the home during fall and winter.
In addition to shading your home and windows with trees and other plants, try to plan your shading strategy to include your outdoor HVAC unit. By shading your condenser unit, it won’t have to work as hard. This can potentially cut your air conditioning bill by 15%.
Also consider vines, grass, shrubs, and smaller plants. Trees, grass, and plants create a microclimate that cools the surrounding area. Water vapor that escapes your plants during photosynthesis cools the passing air.
By using these passive cooling and heating window strategies, you will substantially cut your use of the heating and cooling system.
Still, the best way to create a green and energy-efficient home is to integrate passive (non-mechanical) heating and cooling strategies with active (mechanical) systems, such as your heating, ventilating, air-conditioning, and duct system.
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