četvrtak, 16. lipnja 2011.
Conserving Energy by CCRES
CROATIAN CENTER of RENEWABLE ENERGY SOURCES
Conserving Energy by CCRES
What are the biggest energy uses?
Energy use varies by climate zone, since heating and cooling needs vary considerably. However, on average approximately a third of the energy used in a typical U.S. home goes to space heating. Appliances and lighting together account for another third of energy use. Water heating and electric air conditioning are other big uses.
Does it make sense to turn off the lights if I’ll be back in the room in five minutes?
Whether it is cost effective to turn off a light depends on the type of light. Each type has a certain expected operating life in hours. This operating life depends on how many times the bulb is turned on or off. Incandescent lights should be turned off whenever they are not needed. Since these bulbs produce heat, turning them off saves energy in two ways… the electricity to run the light, and the cooling energy it takes (in the summer) to compensate for the extra heat. The cost effectiveness of turning fluorescent lights is different, since they are more expensive to purchase and their operating life is more affected by the number of times they are switched on and off. With fluorescent lights, it also depends on your energy costs. In general, turn off a fluorescent light if the room will be unoccupied for more than 15 minutes. In areas with high electric rates, such as Hawaii, reduce the time to 5 minutes.More info at http://solarserdar.blogspot.com
How much insulation should I add?
In very hot or cold climates, the cost of adding insulation all around the home - ceiling, walls and floor, can quickly pay for itself in energy savings. In a mild climate, insulation will certainly save energy and money, but may not have a simple payback for more than a decade (a simple payback is calculated by dividing the purchase price by the annual energy cost savings). On an environmental basis, however, it definitely makes sense to add insulation since using less fossil fuels helps to slow global warming.
Is an energy audit worth it?
A professional energy audit can provide a homeowner with a detailed picture of where their energy expenditures are going, and how to best invest in efficiency. Using a qualified professional, the cost of the audit can be more than recouped by energy savings in the first year. Watch this site for a web based home energy audit coming soon.
First Steps: free or low cost energy-saving actions
There are many simple efficiency steps for the home which have little or no. Often, it’s just a matter of being smart about energy-related behaviors and making low-cost investments that can pay for themselves with energy savings in less than a year.
Take advantage of daylight whenever possible to reduce the need for artificial lights. For any light that is on more than two hours a day, replace standard incandescent light bulbs with compact fluorescent light bulbs (CFLs). This can save 75% of lighting costs, but be careful not to put CFLs in enclosed fixtures, since they need air circulation. Use desktop or “task lighting” with CFLs whenever possible and turn off overhead lights to save energy. Train yourself to turn off lights when not in use, and install timers or motion sensors for lights that aren’t used often, or for those that people keep forgetting to turn off. Even basic cleaning can make a difference; keep light bulbs and shades clean, since dirt absorbs light, reducing output. For outside lights, motion sensors are a great way to save energy and increase security. For large outdoor lighting, consider sodium lamps.
Appliances & electronics
Most electronics use energy even when they are not on or in “active mode”. This “standby” power can add up to as much energy as your refrigerator uses. To reduce this energy waste, unplug battery chargers, old VCR’s and other electronics that are not in use, or put them on power strips that are easy to switch off.
Enable the “power management” option on all computers and make sure to turn them off at night and remember that a laptop uses 90% less energy than desktop computers.
Run your clothes and dish washers only when full, and if possible. A dishwasher typically uses only 4 or 5 gallons of hot water vs about 15 gallons when dishes are done by hand. Clean the lint trap on your dryer every time, and if possible, dry clothes on a clothes line. (Green Homemaker tip: If air dryed towels are thrown in with a few damp items in the dryer for a few minutes, they'll loose their stiffness). When shopping for a new dryer, look for one with a moisture sensor that shuts off by itself when the clothes are dry.
Brush your refrigerator coils regularly (every six months or so). They're often found on the back of older refrigerators, and in front underneath the door on new models. Since refrigerators and freezers are high-energy users, don’t keep an extra one in use unless absolutely necessary. If you do need an extra refrigerator, then keep it full, as the food and drinks inside help to maintain temperatures when the door is opened.
When you’re ready to replace an appliance, buy one that’s efficient and do your research ahead of time. Often an appliance with the lowest price tag will have the highest energy costs over its lifetime. In the U.S., look for Energy Guide labels to compare energy usage and cost, and choose appliances that are ENERGY STAR qualified to save 40% or more on energy. However, keep in mind that some very efficient appliances, especially those made by smaller companies, might not have ENERGY STAR ratings yet.
Using water uses energy in ways many people may not think of. Delivering water requires a great deal of energy, as does wastewater treatment. Save water (plus the energy it takes to heat the water) by installing low-flow showerheads and aerators on all faucets. Washing clothes in coldwater saves approximately 90% of the energy used by the washer. Wrap your water heater with an insulation blanket, especially if you have an electric water heater. That will reduce stand-by losses. Hot water pipes should also be insulated. For more information on reducing water use.More info at http://solarserdar.blogspot.com
Heating and Cooling
Turn the setting on your air conditioner higher; a 5° higher setting on your air conditioning thermostat will save about 10% on cooling costs. Likewise, lower the setting on your furnace to 68 degrees, and install a programmable thermostat. If you live in a hot or cold climate, insulate your heating or cooling ducts. Other important yet inexpensive measures include insulating hot water pipes and regularly replacing furnace filters. Also, consider a whole house fan that removes heat from the attic and draws cool air in, and plant diciduous shade trees near south facing windows that will prevent solar insolation in the summer while allowing the sun in during the winter. Another first step is ensuring that all heating and cooling ducts are leak-free. Sealing air ducts can reduce heating and cooling costs by as much as 20%.
Air leakage, or infiltration, is when outside air enters a house through cracks and openings. The average home has dozens or even hundreds of small holes where heated or cooled air escapes, wasting valuable energy. Sealing these leaks can significantly reduce heating and cooling costs, increase comfort, and decrease entry of allergens. Low-cost sealing around doors and windows and anywhere else that air leaks occur is a good first step and can save 10% or more on energy bills.
Pools and spas
- Use pool and spa covers to reduce heating costs and chemicals
- Consider investing in solar hot water heating for pool and spa (they often pay for themselves after just a few seasons).
Next Steps: good energy-saving investments
Daylighting is using windows and skylights to bring sunlight into a home. Compared to artificial lights, daylight is brighter, more appealing, and better for visual acuity and color rendering. Recent studies have also shown that daylighting in schools improves student math and memory skills. A home’s climate influences the best way to bring natural light in. In North America, north and south-facing windows are most advantageous for daylighting. Although east and west-facing windows provide good morning and evening light, they may cause glare and let too much heat in during the summer. Another way to use daylight is “light tubes,” which bring light through the roof and attic, around corners, and into living spaces. New home construction can include daylighting as part of the whole house design.
Appliances & electronics
Upgrading to efficient appliances and electronics can save a lot of energy. A U.S. ENERGY STAR qualified dishwasher, clothes washer or refrigerator incorporates advanced technologies that can save up to 50% on energy and water. The ENERGY STAR labeling program includes most home electronics and appliances, (except for water heaters, stoves, and ovens).More info at http://solarserdar.blogspot.com
Since water heating can account for up to a quarter of the energy consumed in a home, selecting an efficient water heater can reduce energy (and water) bills significantly. There are a variety of water heating technologies, each with their own advantages and disadvantages. Following are the three most common types used in homes:
- Storage water heater: the traditional storage water heater has a tank to keep a ready reservoir of hot water. This provides a relatively large amount of heated water available immediately, but requires a very high wattage heating element. When purchasing this type of water heater, look for the most efficient model.
- Demand (tankless or instantaneous) water heater: doesn’t have a storage tank, so it saves on standby energy. It's often placed close to the energy use, such as a kitchen or bathroom, reducing pipe losses. The cost effectiveness of demand water heaters also depends on the home’s water needs. Savings are greatest in homes that use 41 gallons or less of hot water daily.
- Solar water heater: heats water with the sun’s energy for home use or for a pool or spa. They can be used in any climate, but need a backup hot water source for cloudy days or times of high water demand. n average, in the U.S. a solar water heater will lower a home’s water heating bills 50-80%.
Heating and Cooling
One of the first ways to optimize the efficiency of a home heating system is to install a programmable thermostat. Locate the thermostat away from natural hot and cool spots. In the U.S., look for an Energy Star thermostat.More info at http://solarserdar.blogspot.com
Most U.S. homes are heated with either a furnace, which heats air and distributes it through the home using ducts, or a boiler, which provides heat from hot water or steam for radiators or radiant heat floor systems. Older furnace and boiler systems have efficiencies between 56-70%, while modern systems can achieve as much as 97% efficiency. It’s time to upgrade a furnace or boiler if it is more than 15 years old, very inefficient or poorly sized to the home. The payback from investing in a new system depends on how much it is used, since efficiency provides long-term savings. Another way to improve payback is to improve the overall efficiency of the home first, so a smaller (and thus cheaper) heating system can meet heating demand.
Best heating system replacement choices: for cold climates, a furnace should be high efficiency. In the U.S., the efficiency of heating appliances is expressed as the “annual fuel utilization efficiency” (AFUE). Look for an AFUE of at least 90% for homes in cold climates. However, in milder climates with lower heating costs, 80% efficiency may be enough, since the extra investment in efficiency may be difficult to justify on cost alone. Hot water boilers are inherently more efficient than steam boilers, but relatively efficient models are available. Also, note that any change to a gas heating system can impact indoor air quality. The combustion process creates byproducts that are potentially dangerous, so it’s important to ensure proper exhaust and ventilation. A sealed-combustion furnace or boiler might solve this problem.
There are many ways to cool a house without using an energy-intensive air conditioner. Combining proper weatherization, shading, and ventilation can keep homes cool in all but the hottest and most humid climates. A whole-house evaporative cooler (or “swamp cooler”) can do the job of air conditioners with much less energy for use in climates that are both hot and dry.
New air conditioners are much more efficient than old ones, so for homes that need this technology, an upgrade may be in order. New air conditioners should have an Energy Efficiency Rating (EER) of 11 or higher.
Weatherizing a home involves a number of steps to decrease air exchange with the exterior environment. Windows and doors can be upgraded, air leaks can be fixed, and insulation can be added in walls, floors and ceilings.More info at http://solarserdar.blogspot.com
Air Sealing: By sealing the air leaks in a home’s walls, floors, and roof, a homeowner can save up to 10% on annual energy bills. Air sealing includes adding weather stripping around windows and doors to reduce drafts, using caulking around openings in walls around ducts and plumbing, and sealing larger gaps with expanding foam. When air sealing, it’s important to remember that a home should have some form of ventilation to maintain healthy indoor air. An average home can be sufficiently ventilated with a simple bathroom exhaust fan, properly designed and installed for this purpose.
Insulation: upgrading a house’s insulation can reduce energy usage by up to 20%. Insulation minimizes the heat that travels through walls, ceilings and floors. For an older home, having a professional energy audit is the best way to determine if a home needs insulation, as well as where air leaks are occurring. A homeowner can also visually inspect walls, ceilings and floors. The higher the “R-value” of an insulating material, the more energy efficient it is. Look for an R-value of R-13 for walls, and at least R-19 for ceilings. Most U.S. homes should have between R-22 and R-49 insulation in the attic.
Windows and doors: Upgrading exterior doors can save energy. An exterior door that is old, not properly installed, and not properly air sealed can leak a lot of air from in a home. Once insulation and air leaks are addressed, consider replacing single-pane windows with double-pane windows. Double-pane windows made of high performance (low-emissivity) glass and that contain gas can reduce heating and cooling costs by up to 15%, assuming they are installed and sized properly.
Big Steps: designing and remodeling a home
Passive solar homes
A home can be designed in a way that takes advantage of the sun’s free heat and light. This is called passive solar home design. Essentially, it’s constructing the walls, floors, and windows in such a way that they collect, store, and distribute solar energy in the form of heat in the cold season. In the hot season, they reject the heat to keep the home cool. A passive solar home’s design must take into account climate and site-specific factors such as the angle of sunlight.More info at http://solarserdar.blogspot.com
The U.S. Department of Energy specifies five elements of a complete passive solar home design:
1. Aperture (Collector): this is the window area where sunlight enters the building. In the U.S., this should orient to within 30 degrees of true south and must not be shaded between 9 am and 3 pm during the cold season.
2. Absorber: the surface within the home that absorbs heat from the sun. It sits in the direct path of sunlight, and could be a masonry wall, floor, or partition.
3. Thermal Mass: the materials that store heat from the sun. This is the material below or behind the absorber, and may form a floor or wall. Cement tiles provide excellent thermal mass. The more mass in a home, the longer for the effects of temperature swings to be felt. Thermal mass allows for ride through of a short hot or cold spell.
4. Distribution: how the collected and stored solar heat circulates throughout the house. This is mainly accomplished through the three natural heat transfer modes (conduction, convection, and radiation). Fans, ducts and blowers may also be used.
5. Control: keeping sun out during the hot months. Awnings, low-emissivity blinds, and fans, vents and dampers restrict heat flow during the season when cooling rather than heating is needed.
Existing homes can be retrofitted to passively collect and store solar energy. Elements such as window location, window types, insulation and air sealing, and even landscaping can play an important role in using the sun’s natural heat and light to reduce a home’s energy needs.
Zero energy home design
A “zero energy home” is one that produces all the energy it needs, and maybe more. By combining energy efficient construction and appliances with renewable energy systems such as solar water heating, solar electricity or even geothermal or wind-generated electricity, a zero energy home is good for the planet and good for its occupants. These homes are environmentally sustainable in that they save energy and reduce energy-related pollution. Zero energy homes typically have improved comfort due to less temperature fluctuation, and they protect the owner from fluctuations in energy prices and, depending on how they are designed, from power outages.More info at http://solarserdar.blogspot.com
Some design features of a zero energy home include:
Passive solar heating and cooling
Energy efficient appliances and lighting
Solar electric and solar water heating systems
Environmental and Economic Benefits
Global warming: Except for the small percentage coming from renewable sources, the energy used by homes adds greenhouse gases to the atmosphere. In fact, fossil fuels are responsible for over 80% of the global warming problem.
Air pollution: In addition to warming the planet, fossil fuels burned for energy production add unhealthful emissions to the air we breathe every day.
Homeowners across the U.S. are buying into the idea of energy efficiency. A 2007 survey by the National Association of Home Builders found that home buyers would be willing to spend nearly $9,000 more on a home purchase if the home had green features that would save them on their utility bills.
A Newsweek article (March 17 2008) highlighted a couple living in Grapevine, Texas whose home is so efficient that the heat hardly kicks on even on the coldest days. Their house is packed with green innovations, including a 10,000 gallon tank to collect rainwater from the roof, and solar panels to heat their water. Yet homeowner Ross Bannister says people are sometimes surprised to hear about the home's advanced technology, since on the outside it looks like a classic Texas farmhouse.
A couple in North Bend, Washington invested in a geothermal system that cost them more than twice what a traditional heating and cooling setup would. Yet they calculate they will recoup their costs in six years, and they’ll feel good about reducing their carbon footprint along the way.
More info at http://solarserdar.blogspot.com
CROATIAN CENTER of RENEWABLE ENERGY SOURCES (CCRES)