Meant to add more, but accidently hit post. Window tinting is great for that and blocks out most of the sun's UV rays from making the room less than tolerable, unless you have a sunroom, in which case it's probably moot to make those windows a darker shade. Also, another point of reference for air leaks is up in the attic. For those who attic insulation, all the cold or hot air locked up there will find its way down inside your home faster.
Great point about hidden air leaks. I remember seeing tiny cracks in the window sill that most likely were made from bugs (not termites, thankfully) and passed out through whichever hole in the siding was visible. It's hard to say how much of this dinged my bills when the outside temps were bearable, but I can honestly say they made the winter and summer months brutal on the ol' electric bill. After I patched those up, I had to install new window pane film to the looser parts of some of my windows frames. Remember, the thinner your window panes, the more susceptible a home can be to escaping air, as well.
Above you and hiding out of sight may be a home owner’s biggest air leak, causing your energy bills to be higher than they should be. Behind the grill and off to the side of a bathroom ventilation fan, there's an exhaust vent several inches in diameter leading straight outside for each ventilation fan you have. At the outlet point, if it’s horizontal, you probably have a fixture with several louvers that surely don’t seal very well. I’ve seen and heard the wind have its way with those louvers several times. If it’s vertical, you probably only have a rain cap covering it. They both may do a nice job of keeping the rain out, most of the time. The vertical orientation is just like a small chimney and once an upward draft of warm air is started, it will continue costing you more than you want to know. Builders switched to the horizontal orientation to reduce the chance of water damage from going through the roof and to reduce the chimney effect.
With the wind blowing across either exhaust vent orientation, you will get a venture effect. Where the wind will suck out the air inside your house, sure it may not be much, but it all adds up and you may be surprised on how much is lost. Back at the housing of the ventilation fan, there’s a back draft preventer. If it’s still there and working properly, it will stop most of the wind after getting by the louvers. If you look closer at that backdraft preventer, you will notice that it also doesn’t seal very well either, and it’s only to prevent air from going into the house, not out.
The solution my company has found for this issue is a replacement fan insert that has a built-in damper. The two different sizes that are currently available are the two most commonly used ventilation fan housings from the Broan and NuTone companies. The replacement fan assembly uses the weight of the moving parts of the motor to hold a damper close when the motor is not running. This true damper seals the exhaust vent so air cannot move in either direction.
The test house saved seven percent on its heating bills over the winter season, and that’s a nice return for how little money the replacement insert fans costs, especially if you compare it to a new furnace, windows, air conditioner or added insulation. We thought the replacement insert fans would also help in the summer keeping hot air outside when using air conditioning. But because of the fan’s built in damper, it really helped in keeping the humidity out, and we were surprised on how well it worked. The test house saved a lot more money on electric bills during the summer when the central air was running then we dared to hope for. How much it will save you during the summer depends on where you live and how much you use your air conditioning along with how hot and humid it gets in your area and for how long and just to be clear, the test house is located in Michigan. From the best estimates we could use to compare the test house with neighboring houses, we figured the test house save over fifty dollars a month on the electric bill from the central air not running as often. Also, for houses with a second floor, where the two fans are located on the test house, it was noticeably cooler and more comfortable on the second floor than previous years. The second floor was still warmer than the main floor, but anyone who has a two story house and uses air conditioning can tell you, it’s not easy or cheap to cool the second floor.
Another nice feature of the product is that it can be installed from within the house with just a common screw driver if needed, and a short ladder to reach the fan itself. You can replace the fan yourself in just a few minutes. The ventilation fan housing and the motor mounting plate are made of sheet metal and may have burrs along the edges, so be careful of that. The expected payback period for this product from current customers can range from a few months to 15 months, depending on what time of the year you install it, your local electric rates (especially true for those who use air conditioning) and what type of fuel you use to heat your house. You can find more information about the replace ventilation fans from the Larson Fan Company and the full installation instructions at http://www.larsonfan.com. The two replacement fans in the test house have reduced the annual energy bill of the test house by over ten percent. Currently the average home uses between 2200 and 2500 dollars for the energy it uses each year.