Screens mounted outside windows, like this SunScreen panel, can block more than half of the sun’s heat from reaching the pane.
Question: My home has a lot of windows and on sunny summer days my air conditioner struggles to keep the house cool. Are there ways to reduce the heat transfer through the glass?
Answer: Direct and indirect heat from windows and doors does increase the temperature inside your house significantly. Even the most energy-efficient models don’t insulate as well as a typical house wall. Awnings can help, but for windows exposed to direct sunlight, consider installing sun-control window screens like the SunScreen panels from Phifer (phifer.com). The mesh is a dense weave of strong, dark-colored polymers that can block more than half of the sun’s heat before it hits your window pane, but you can still see through the screening so visibility isn’t impaired. - JIM DULLEY
Question: How do whole-house fans work and can they help reduce my air‑conditioning bill?
Answer: Prior to the wide-scale adoption of air conditioning, many people used open windows and fans to ventilate and cool their homes. This method still works, and in certain conditions, a whole-house fan can help cut your energy bills by working in conjunction with your air-conditioning system.
A whole-house fan is a powerful blower (think of a bathroom vent fan on steroids) mounted in the ceiling that pulls hot air from living spaces into the attic where it’s pushed outside through soffit vents. This creates negative pressure inside the home and draws cooler air in through open windows and doors.
Of course, a whole-house fan only works if the outside air is cooler than the air inside your home, which is why you’ll want to run it at night and only during cooler seasons. When conditions are right, the advantage of using a whole-house fan is that it also cools walls, floors and ceilings and this can delay the start up of your air-conditioning system until later in the day.
Equipment costs for a whole-house fan range from $150 to $350, and they cost roughly 1 cent to 5 cents per hour to operate (compared to 8 cents to 20 cents per hour for an air conditioner). Professional installation is recommended. The seals must be tight in order for the system to work, and the fan needs to be properly sized—it should be powerful enough to change the air in a home 30 to 60 times an hour.
There are some drawbacks. Whole-house fans are not recommended for anyone with severe allergies or breathing problems because windows must remain open for the system to work. The fans can be noisy, especially at higher speeds. And in the winter, you’ll need to place a cover over the fan to keep warm air from leaking into the attic. - BRIAN SLOBODA
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