That foggy patch indicates that the airtight seal between the panes has weakened and allowed moisture between the two layers of glass. This doesn't necessarily mean that the energy-saving performance of the windows has been significantly reduced. Even if this had been a sign of lowered efficiency, replacement wouldn't be recommended. Replacing a window for energy-saving reasons, alone, usually is not cost-effective.
Don't get me wrong; I'm all for energy-efficient windows. But they're an investment, and one that is unlikely to pay for the full replacement cost in energy savings. However, if you've got to replace a window that is non-functional or if you need one for a new space, by all means get the best, energy-efficient window you can afford. At that point, an energy-efficient window becomes cost-effective, because your energy savings will pay for the difference between the price of a basic window (an amount you're going to pay, regardless of what window you pick) and the higher price of an energy-efficient window.
If buying new windows, look for a U value of .32 or lower to keep heat in. And, unless you're installing east- or west-facing windows, which are most subject to overheating in the summer, look for a solar heat gain coefficient of at least 0.4 to allow in more heat from the sun.
A. I bet you wish there were a quick and easy answer to this, but tackling mildew takes a little effort. When it comes to mold and mildew, bathrooms offer the perfect, moist environment. If you have a mild mildew invasion, you can clean the affected area with a diluted solution of bleach and prime it with a mildew-resistant sealer before painting it again.
It sounds like your problem may be more serious. Your first step should be to eliminate the source of the moisture if there are any leaks, but you might also have a ventilation problem. Does your bathroom have an exhaust fan? It should, and if you hold a square of toilet paper up to the intake grill, the paper should stay there when the fan is on. If it doesn't you have a problem with either the fan or the ductwork. Ductwork should be smooth-wall, not the corrugated flex duct, and vented to the outside. If you need to replace or install a fan, choose a quiet one (less than two sones, the unit that measures sound), and less than 50 watts that meets the guidelines of the Vermont Residential Energy Code. All ENERGY STAR labeled fans meet the code guidelines. Operate the fan as much as necessary to control humidity and always run the fan after showers until the walls are dry, which could be several hours.
A properly working exhaust fan should help solve future problems, but you may also need to take care of any mold that may have established itself. For more information on mold contact the Vermont Department of Health at 1-800-464-4343 or visit their website page about mold at healthvermont.gov/enviro/indoor_air/mold.aspx.shtml.
Q. Our home was just built, so why do we have condensation on our windows?
A. Your home's newness may actually be the cause of the condensation you're seeing. Humidity in the air is caused by people, animals, plants, cooking and bathing. But in new homes, a great deal of moisture also comes from the construction materials, especially from the concrete foundation.
The condensation on your windows is a sign that the relative humidity in your house is too high and causing water vapor to collect on colder surfaces. It's a good idea to have a hygrometer in your home to keep track of indoor relative humidity. Generally, you want to keep it between 30 and 50 percent, lower in the winter to help reduce condensation potential.
Usually, new building components will have lost most of their moisture and the relative humidity levels will drop within a year of completion. In the meantime, you can reduce the humidity by adding more ventilation within the house, such as a bathroom exhaust fan or range hood. Due to potentially high power consumption, dehumidifiers should be the last resort.
Q. Other than using a dehumidifier, what can we do to help dry out our wet basement?
A. There are lots of things that can cause a wet basement. In fact, I could write a whole article just on this topic. But let's start with the simplest reasons:
The first thing to check is that water drains away from your house. The exterior grading (ground) should slope away from your house so water runs away from the foundation. Sometimes water will leak in when it never used to because the gutters or drain spouts are plugged and water off the roof saturates the ground too close to the house. If you have gutters, check to make sure they're clean and that the downspouts extend away from the foundation by at least two feet.
If your ground is sloped and all gutters are in working order, a high groundwater table may the culprit. One fairly easy way to tackle this problem is to install a sump pump which draws water from beneath the slab and pumps it away from the house. The pump sits in a hole, or sump, that extends below the slab. When water collects in the sump, the pump turns on automatically and removes the water through a discharge hose that exits the basement above grade. Just make sure the hose ends several feet away and downhill from the foundation or you'll be pumping the problem right back in!
A. Never underestimate the power of ventilation in a home. Ventilation removes and dilutes pollutants, provides fresh air and may improve the durability of your home.
Exhaust ventilation, which is what happens when you run the bathroom fan, is a good ventilation strategy. Air that's pulled out of the bathroom causes replacement air to be drawn in through the small holes that are distributed throughout your home's structure. This diffuse introduction of fresh air means that a single fan can often ventilate the whole house. Just as important, removing bathroom moisture before it migrates around the house means you can reduce problems with window condensation, mold, mildew and other threats to a building's longevity.
It's true that you lose some heat and use some electricity by running the bathroom fan, but at today's energy costs, it's probably less than $100 for the whole year, even if you leave the fan on 24 hours a day. I'd call that a pretty good bargain for fresh air.
Q. My bathroom fan is really noisy. Is that a sign that it's wasting electricity?
A. If you can hear the fan throughout the house - or even in nearby rooms - when you use it, chances are it's an energy hog.New energy-efficient fans are generally quiet. It's important to have proper ventilation to help maintain good indoor air quality, so leaving the fan off isn't a good solution. Instead, look for a fan that uses less than 50 watts and has a noise level of less than two sones, the unit that measures sound. This information is available on the fan and in the literature that it comes with it. You'll want a fan that you won't notice in the next room or on your power bill. All ENERGY STAR labeled fans meet the recommended wattage and sound standards.
Q. Are there energy-efficient dehumidifiers?
Yes. Look for an ENERGY STAR labeled dehumidifier. It removes the same amount of moisture as a similarly sized standard unit, but uses 10 to 23% less energy. These are high quality units which have more efficient refrigeration coils, compressors, and fans than conventional models. Over the lifetime of a machine, savings can add up to about $200.
Q. I've heard that dehumidifiers can use a lot of electricity. Is this true?
A. The short answer is, yes. But as with most energy-related questions, it's not that simple.
Running a dehumidifier in a wet basement, for example, could cost you as much as $31 a month. However, if you'd like to replace an older dehumidifier or are looking to buy a new one, look for the ENERGYSTAR. Newer models have more efficient compressors and use considerably less energy. Here are some things to keep in mind about using a dehumidifier:
- Dehumidifiers are only effective for controlling humidity in an enclosed area and need to be sized appropriately. The ENERGY STAR website at www.energystar.gov can help you choose the right size or give us a call.
- Contrary to popular belief, if you're trying to dehumidify a basement during the summer, keep the windows closed.
- If humidity in your living areas is a problem, a properly sized air conditioner can be more effective and energy-efficient than a dehumidifier. Again, keep the windows closed.
- The best way to control humidity is to track down and reduce or eliminate the sources of moisture.
- In the winter, use exhaust ventilation.
