A: Glad to. I'd wait until the old air conditioner fails. Here's why: The decision has to do with whether or not the energy savings from a new unit would pay for your purchase in a reasonable time. Savings depend on the age of the air conditioner, its size, and how much you use it. If your current unit had been manufactured before October of 2000, I'd be likely to recommend replacement, because a new ENERGY STAR qualified air conditioner is 25% more efficient than those older models.
But yours is newer. Today's ENERGY STAR qualified models are 10% more efficient than air conditioners made since 2000. So, your savings wouldn't be large enough to justify replacement of a functioning unit.
Another factor that makes waiting a good idea is the simple fact that we're in Vermont. Few days in a typical Vermont summer are hot enough for air conditioning, so I'm going to estimate that your air conditioner is on for only 100 hours per month for three months. Compared to most places in the U.S., that's a very short season of use for an air conditioner! Based on that usage, your annual air conditioning electricity bill, for your size unit, would be about $48. That's about $5 more than a comparable ENERGY STAR qualified unit would cost to operate.
So, unless you use your air conditioner a great deal more than I've assumed, you can see why it's logical, financially, to wait to buy a new unit. Once your old air conditioner fails, it definitely will be worthwhile to buy an ENERGY STAR qualified model.
Q: We have central air conditioning, but we try to use it as little as possible, to save on our electric bills. Can you tell us the best ways to keep the house cool without air conditioning?
A: Sure, that's fairly easily done, especially in Vermont where air conditioning is rarely needed. Here are some tips:
- In the cooler hours of the evening and early morning, open your windows. Use a window fan, blowing toward the outside, to pull cool air in through other windows and to push hot air out.
- During the day, close coverings on the windows that get direct sunlight. On hottest days, keep the windows closed. External awnings and trees also provide shade for windows.
- Delay heat- and/or humidity- producing activities, such as dishwashing, baking, showering, or doing laundry, until the cooler evening hours. Always use a bath fan when showering.
- Use an exhaust fan, directly to the outdoors, to blow hot air out of your kitchen while cooking. The savings in your cooling costs far outweigh the electricity use of the fan.
- Caulk around your window frames and exterior door frames and use weather stripping on exterior doors.
- Seal any holes and gaps between the attic and your living space and see that you have a minimum of 12 inches of insulation in the attic. Hiring a professional is the most effective approach to air sealing and insulation. You can find a Home Performance with ENERGY STAR® certified contractor at www.efficiencyvermont.com/homeperformance.
- Use compact fluorescent light bulbs (CFLs). Incandescent light bulbs use only 10% of their energy to produce light. The rest is released as heat. CFLs produce only a fraction of the heat and don't waste electricity.
- Be sure that the clothes dryer is vented to the outdoors. In addition to reducing heat in the summer, this is important year-round for indoor air quality and for preventing damage to your home from moisture, mold and mildew.
Q. Can you suggest any energy-efficient alternatives to air conditioners?
We're lucky in Vermont, because we don't experience too many summer days when air conditioning is really necessary. You can extend those non-AC days by following some of the same steps you use to stay comfortable in the winter.
Moving air helps you feel cooler. Ceiling fans and box fans can help fulfill your need for air conditioning at a much lower cost.
Open your windows at night and run the exhaust ventilation, then close the windows in the daytime. Drawing shades or blinds on east- and west-facing windows on sunny days will reduce the heat gain from direct sunlight in your home.
If you do decide to resort to an air conditioner to keep things cool, look for the ENERGY STAR and choose one properly sized for the room. ENERGY STAR qualified room air conditioners use at least 10 percent less energy than conventional models. Replacing a 10-year-old room air conditioner with a new ENERGY STAR qualified model can save you an average of $14 per year on your electric bill.
Many people buy an air conditioner that is too large for the space they plan to cool. For tips on choosing a unit that's properly sized, visit www.energystar.gov.
Q. Any tips on keeping the heat out of my house this summer?
A. Have you ever seen old photos of homes with awnings? You can bet most of those photos were taken in the days before air conditioning was common. One thing our ancestors realized was that direct sun is the biggest source of heat gain. You can take a lesson from them and shade windows that admit direct summer sun, especially on east and west sides of the house.
The same air sealing, insulation and ventilation that keep your home warm and dry when it's cold go a long way toward reducing or eliminating the need for air conditioning when it's hot. You can start by sealing all holes between the house and the attic. In summer, these holes allow hot attic air into the house as cooler house air sinks and pulls replacement air through openings high in the building.
Check to see that your attic insulation covers every inch of ceiling surface, including the framing. If you have sealed holes between the house and attic, you may add insulation to the ceiling. Well-installed insulation is more important than a lot of insulation. Blown cellulose insulation is a good choice for adding insulation since it fills gaps between fiberglass batts and conforms to framing irregularities.
Q. How can I choose the most energy-efficient room air conditioner for those hot summer nights?
A. The easiest way to make sure you're choosing an energy-efficient room air conditioner is to look for the ENERGY STAR label. Room air conditioners are also rated for efficiency using a number that refers to their "Energy Efficiency Ratio" or EER. The higher the EER number the more efficient the air conditioner. Visit our Rebate Center for a listing of available rebates on ENERGY STAR air conditioners.
Also besides buying the right model you need to buy the right size. Many people buy an air conditioner that is too large for the space they plan to cool. For tips on choosing a unit that's properly sized, visit www.energystar.gov or give us a call for more guidance on sizing.
Q. Do electric fans use much energy? If I'm buying a new one, what should I look for?
A. Are you thinking about using a ceiling fan or a window (box) fan? Depending on the speed, a window fan will use about 150 watts. People often choose window fans to cool off a room - or an entire house. If you chose to leave your window fan on round-the-clock, it would use about 3.6 kilowatt-hours per day, which would cost you about $13.50 per month.
If you're considering a ceiling fan, remember that these are used to cool people, not rooms, so be sure to turn the fan off to save energy when the room is not occupied. Ceiling fans that have earned the ENERGY STAR rating move air up to 20 percent more efficiently than standard ceiling fans. This can save you from $15-25 per year on utility bills, plus any additional air conditioning or heating savings you may gain when your fan is operated properly.
Q. My house gets very hot in the summer. What do you think of a whole house fan?
A. I think you should consider some alternatives before you decide. One usually thinks of whole house fans in climates where summertime heat is a big comfort issue. Here in Vermont, we can usually keep our homes comfortable most of the year with good insulation, air sealing and summer shading of large windows to the east and west. For that reason, I suggest you spend your comfort improvement dollars on increasing the overall performance of the "shell" of your home ? a tactic that should make your home more comfortable in summer and have the added benefit of energy saving in the winter - all without the added electrical cost to operate a whole house fan.
If you decide to purchase a whole house fan, look for a moderately sized one that has a well-insulated and sealed cover with a motorized opener (such as the one made by Tamarack).
Whole house fans are large powerful fans usually 20-48 inches in diameter with a one-quarter to one-half horsepower motor. These fans can move enormous amounts of air, so you'll need openings in your attic large enough to allow adequate roof ventilation.
To operate your fan properly, wait until outdoor temperatures are cooler than indoor temperatures and use the fan to flush hot air out of the house.
