- Upgrading Attic Insulation
- Energy Efficient Window Film
- Fixing or Replacing Leaky Air Ducts, or Air or Thermal Leaks</span>
- Energy Efficient Lighting, Heating or Cooling Systems
- Solar Energy Systems
This article will explore the options to address energy efficiencies in these areas.
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Upgrading Attic Insulation
Reducing house heat or cooling loss through the attic can we one of the best things to focus on to make your house more energy efficient -- especially if it is an older house. There are a number of options to consider here.
Fibre insulation is typically blown into the attic or laid down in rolled sections called batts. Fiber can be made out of fiberglass, cellulose, mineral wool or sheep's wool. Fiber insulation in the attic is placed between and on top of the rafters. It reduces energy loss by stopping heat or cool from escaping from your living areas into the attic.
Each of these materials have "R" values which represents the materials resistance to heat flow. The higher the R value, the better the insulation of that material and, in general, the more expensive the material is. The amount of insulation or R-value you'll need depends on your climate, type of heating and cooling system, and the section of the house you plan to insulate.
Here's a good link to determine how much insulation to add to a new or existing house: Insulation Calculator
Rolled in insulation can be a fairly easy do-it-yourself project, but blown in insulation is almost often a professional job.
Blown in insulation has an additional advantage over rolled in insulation as it doesn't leave gaps in which heat or cool can escape.
Properly insulating your walls and ceilings can save 25% of your home heating bill and 1 ton of carbon dioxide a year.
Spray-In Foam SealingEdit
Spray-in foam sealing is a different approach to energy loss and is becoming more popular in new home construction. The foam is generally made polyicynene or polyurethane although other variants exist.
Spray in foam is almost always professionally installed and is applied to the underside of your roof and completely seals the attic from any air leaks from the attic.
This approach is very energy efficient and substantially reduces the temperature of your attic in the summer and increases it in the winter as the temperatures more closely represent those that are in your living spaces. An additional benefit of spray in foam is that it is also a noise barrier.
A thermal shield is also a reasonably new method of insulation. A thermal shield is a thin layer (looks like tin foil) that reflects radiant heat escaping from your living areas back into them instead of letting it escape into the attic. When installed in the attic, it can be either laid on top of the rafters, or applied to the underside of the attic roof or a combination of both.
Energy Efficient Window FilmEdit
The U.S. Department of Energy estimates that during the summer up to 60% of a home’s cooling energy is lost through its windows and during the winter up to 25% of a home’s heating energy is lost through its windows.
If you have very old single pane or leaky windows, the best option is to replace them. However, if you have windows that aren't leaky, their energy performance can be substantially improved by adding energy efficient window film.
This film allows most visible light to pass through (usually around 80%). They block almost all (usually ~98%) of harmful ultraviolet light and most infrared solar heat. This means that in the summer about 70% of solar heat is prevented from entering your house and in the winter, about 40% of heat is prevented from escaping outside through your windows. There are many manufacturers of these products and you can dial the performance you'd like to a certain level.
Energy-efficient window films can be installed professionally or they can be a do-it-yourself project.
Fixing or Replacing Leaky Air DuctsEdit
This is a critical area of focus for older houses with forced air heating and/or cooling. The problem is that, over time, the duct system that carries the hot or cool air develops leaks and becomes inefficient. Since the ducts typically run through the attic, or in the basement or under-house crawl space, the leaks mean heat or cool is lost to non-living spaces. With an older house or in a house where ducts could have been damaged, leakage could range up to 50% or more which is a huge loss of energy efficiency and money waste.
Unfortunately, it is not easy to determine if you have leaky ducts by yourself. The only way to be sure is to hire a professional heating/cooling expert who is properly equipped to do a thorough duct test. To do this, all of the vents into which heating or cooling enters your living spaces are blocked (with tape or temporarily installed coverings) and then a blower is applied to the ducts to pressurize the duct system and then leakage is measured with a professional tool.
If it is determined that your ducts are leaky, they can either be fixed by replacing sections or sealing them with tape or spray-on sealant or the duct system could be completely replaced.
In addition to sealing leaks, the energy efficiency of your ducts can be improved by adding insulation to the ducts if they do not have them. This insulation surrounds the ducts and further reduces heating or cooling loss.
Fixing Air or Thermal LeaksEditDoing a house leakage test will find leaks by executing a blower door.
Thermal leaks are areas that could come from air leaks, but may also be areas where heating or cooling is escaping without any air leakage. These leaks are often hidden. An example of this type of leak is an area in walls or ceilings that does not have adequate insulation or where the insulation was improperly installed or damaged. These types of leaks cannot be detected with a blower test (see above) so require another method to identify called thermal imaging.
Thermal imaging uses a special camera to identify which makes areas of heat or cold easily that are different from the surrounding areas easily identifiable.
The images to the left show an area around a window using a normal camera and using a thermal camera . With the thermal image, you can clearly see that there is an area around the window that has a thermal leak that is not visible from either the inside or outside that needs to be addressed.
Thermal imaging is typically done by a professional because the best thermal cameras can be very expensive, but if you have one or want to buy one, using it to find hidden leaks in your house can be relatively easy. However, some hidden leaks can be very subtle so it may be easy for a an inexperienced person to miss the leak when looking at a thernal image.
Energy Efficient LightingEdit
The two best options for improving the lighting energy efficiency over standard incandescent lights are:
Compared to incandescent lights, Compact Fluorescent Lights (CFL) are four times as efficient, last up to ten times longer and use 50-80% less energy. While they are initially more expensive, they are cheaper in the medium and long term.
Early CFLs had a very cold, bright light that was not as "warm" and likeable as incandescent lighting but newer products are better at imitating the incandescent glow.
Another reason why people dislike CFLs is that, unlike incandescent or LED lighting, CFLs take time to warm up to full lighting.
One environmental concern about CFLs is that they contain mercury. While the quantities included in a bulb are so low to not be of concern to a household that breaks one, the amount of mercury that could potentially be exposed to the environment as they fail and are thrown away is a long term concern for these bulbs. In many cases, one must recycle expired CFL bulbs. This way, the mercury vapor can be captured safely without being released into the atmosphere.
Light Emitting Diode (LED) lighting are superior to both incandescents and CFLs. They last up to five to ten times as long as CFLs and are generally over twice as efficient as CFLs. In fact, LED manufacturer Cree offers a 10-year warranty for its bulbs. LEDs use no mercury, and they are more durable due to a more solid construction so they better withstand jarring or bumping. The Cree LED bulb has a heat sink so that energy is not lost as heat and can instead be used to light the bulb.
As with CFLs, early generations of LEDs had a pale, bright light, but recent versions can produce light almost identical to the hue of incandescents.
The only major downside of LEDs is that they are more expensive than CFLs. However, over the LED's lifetime, they are be cheaper than CFLs.
Energy-Efficient Incandescent LightingEdit
While more efficient incandescent lights such as halogen lighting have existed for a long time, research and development of energy efficient incandescent lighting continues. Based on recent laws, one misconception is that incandescent light bulbs will become illegal. However, the law only sets mandatory standards for lighting efficiency.
Some manufacturers like Philips have introduced a newer generation of incandescent bulbs that are ~30% more efficient. While not nearly as efficient as CFLs or LEDs, an energy-efficient incandescent lightbulb is a lower-cost option of improving lighting efficiency. Further research and development could help improve this.
Comparison of LED, CFL, and Incandescent LightingEdit
The following table compares some of the key characteristics of LED, CFL and incandescent bulbs. It should be noted that bulb costs can vary greatly over space and time, and new generations of bulbs further improve performance. However, this table does provide a good basic comparison.
|Light bulb projected lifespan||50,000 hours||10,000 hours||1,200 hours|
|Watts per bulb (equiv. 60 watts)||10||14||60|
|Cost per bulb||$35.95||$3.95||$1.25|
|KWh of electricity used over|
|Cost of electricity (@ 0.10per KWh)||$50||$70||$300|
|Bulbs needed for 50k hours of use||1||5||42|
|Equivalent 50k hours bulb expense||$35.95||$19.75||$52.50|
|Total cost for 50k hours||$85.75||$89.75||$352.50|
The following table compares the total houshold cost for LED, CFL, and incandescent bulbs over 50,000 hours, assuming 25 bulbs per household.
|Total cost for 25 bulbs||$2143.75||$2243.75||$8812.50|
|Savings to household by switching|
This clearly illustrates the long term cost savings of both LEDs and CFLs over incandescent and even though LED lights are ore expensive than CFLs, they still are slightly cheaper over the long term.
Energy Efficient Heating or Cooling SystemsEdit
If your house has an old furnace or central air conditioning system, a great way to improve energy efficiency is to upgrade to new energy-efficient systems.
A good rule of thumb is that it's time to replace your equipment if:
- your heat pump or air conditioner is more than 10 years old,
- your furnace or boiler is more than 15 years old,
- your equipment is breaking down often, or
- your energy costs are rapidly increasing.
There are many options to increase energy efficiency of heating and cooling systems. The most common options are:
- forced air heating
- heat pumps (for heating and cooling)
- hydronic heating
- radient heating
Forced Air HeatingEdit
Forced air heating is a traditional heating system that utilizes gas burners which then heat a large metal chamber. The air is pushed over the metal chamber, warmed and then forced through ducts into various rooms by an electrical fan. Since hot air rises, the air near the ceiling may reach 82 degrees while the air near the floor might be only 69 degrees. The higher the ceiling is, the greater this effect becomes. Homes that include vaulted ceilings experience enormous comfort and efficiency challenges with forced air systems. Furthermore, conventional systems often leave houses with hot and cold spots as well as drafts. When purchasing a system look for Energy Star rated systems that have the highest efficiency you can afford.
Heat pumps are another traditional system used widely. They are extremely energy-efficient, but they tend to be more complex in that they can double as an air conditioner. Heat pumps are powered by electricity, but the electricity used in a heat pump operates differently then expected. It uses an electric motor not a heat coil; therefore, it uses far less current. With heat pumps, more energy is supplied than consumed, simply because heat is extracted from the air and water within its surroundings. For these reasons, heat pumps can circulate more air and last for longer periods of time. Another advantage of heat pumps is because they are powered by electricity, solar panels could power your heating and cooling systems for free or at reduced cost. Additionally, you have the option of installing geothermal-run heat pumps which run long pipes through the ground to use the nearly constant temperature of the Earth as a highly efficient method to generate heating and cooling more efficiently than standard heat pumps. As with forced air systems, look for Energy Star rated systems and buy the highest efficiency system you can afford.
Hydronic heating is a heating system that uses water. It can be used with forced air or radiant heating systems. With hydronic forced air applications, heated water is passed through several long, narrow baseboard-style radiating units and a blower pushes the cool air across the units. As the cold air passes over the units, the air is heated and directed to the living area. Unfortunately, this option often causes hot and cold spells.
Radiant heating systems increase comfort, economy, and flexibility. The heated water is run through pipes in the floor (or walls) and the floor gets warm as the heat radiates into the living area. Radiant systems provide a more constant heat than forced-air options.
Radiant heating systems are considered to be the best of the best. Unfortunately, radiant heating systems can be very expensive to install and maintain. However, they also use less energy than comparable forced air systems which will end up saving homeowners lots of money. Radiant heating systems can use 20% to 40% less energy to heat the same space, while maintaining a much more comfortable heat level.
Boilers are important considerations with radiant heating systems. The boiler is responsible for heating the water that circulates through the baseboard radiators or the tubing in the floor. Without a sufficient amount of heated water, the baseboard radiation and tubing will not have enough heated water to radiate into the home. For this reason, choosing the right boiler can make or break a system.
The trick to saving money with a radiant heating system is to connect an individual water heater to the boiler. This will heat a greater volume of water more efficiently than a conventional water heater. The truth is that conventional water heaters heat about 40 to 50 gallons of water in an hour at 55% efficiency. By connecting a conventional water heater to a boiler, it will heat 200 gallons or more in an hour at 87% or more efficiency. For households that require a lot of water, the ladder is the most logical choice.
Solar Energy SystemsEdit
Solar energy systems include photovoltaic (PV) systems and thermal solar systems.
Photovoltaic Systems (PV)Edit
A clean and renewable power source, solar energy is becoming more widely adopted today due to decreasing cost, tax incentives, and leasing options.
Photovoltaic systems use solar panels to gather and convert the sun’s energy into electricity. During daylight, the photovoltaic cells are arranged on a grid-like pattern on the solar panel’s surface to collect the solar energy and convert it into electrical energy. An inverter converts direct current to alternating current that is usable in a house.
Although solar energy can only generate electricity in daylight hours, in many areas of the United States, the power company will pay house owners for energy they generate with solar energy. This enables a strategy in which an owner installs a system which generates more energy than needed in peak energy periods. This excess energy is then "sold" to the power company at high rates which then offset the cost of energy purchased in hours of darkness. Using this strategy, a solar energy home owner can set their energy cost to zero or near zero.
PV systems can be expensive, costing $10,000-$20,000 for small systems up to a $100,000 or more for a large mansion. Costs can be offset by federal and state tax breaks for energy-efficient systems. Return on investment analysis typically creates a break-even scenario in five to ten years.
An additional option for PV systems is to lease them from companies who pay for all the installation costs and maintenance, and then "sell" you energy at rates lower than traditional power companies. This is a good option for saving money and reducing upfront costs, but in the end, you can never reduce your electricity cost to zero.
Thermal Solar SystemsEdit
Another way to harness the sunlight is by using solar thermal energy. This is commonly used for heating homes, providing hot water, heating swimming pools, and space heating. Usually, space and hot water heaters use a storage tank to store the heated water while pool heaters recycle the water by using collectors, often placed on the roof which use the sun to heat the water and return it to the pool or hot water heater.
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