|For climates with moderate heating and cooling needs, heat pumps offer an energy-efficient alternative to furnaces and air conditioners. Like your refrigerator, heat pumps use electricity to move heat from a cool space into a warm, making the cool space cooler and the warm space warmer. During the heating season, heat pumps move heat from the cool outdoors into your warm house; during the cooling season, heat pumps move heat from your cool house into the warm outdoors. Because they move heat rather than generate heat, heat pumps can provide up to 4 times the amount of energy they consume.|
The most common type of heat pump is the air-source heat pump, which transfers heat between your house and the outside air. If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30% - 40%. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months. However, the efficiency of most air-source heat pumps as a heat source drops dramatically at low temperatures, generally making them unsuitable for cold climates, although there are systems that can overcome that problem.
For homes without ducts, air-source heat pumps are also available in a ductless version called a mini-split heat pump. In addition, a special type of air-source heat pump called a "reverse cycle chiller" generates hot and cold water rather than air, allowing it to be used with radiant floor heating systems in heating mode.
Higher efficiencies are achieved with geothermal (ground-source or water-source) heat pumps, which transfer heat between your house and the ground or a nearby water source. Although they cost more to install, geothermal heat pumps have low operating costs because they take advantage of relatively constant ground or water temperatures. However, the installation depends on the size of your lot, the subsoil and landscape. Ground-source or water-source heat pumps can be used in more extreme climatic conditions than air-source heat pumps, and customer satisfaction with the systems is very high.
A new type of heat pump for residential systems is the absorption heat pump, also called a gas-fired heat pump. Absorption heat pumps use heat as their energy source, and can be driven with a wide variety of heat sources.
|THE FUTURE OF HVAC THE PERSPECTIVE OF ONE AMERICAN |
Our technology is constantly changing, sometimes because of new discoveries and sometimes because of influences outside our industry.
As recently as this century, central, indoor climate control was available to only a privileged few. Today, even central air-conditioning in homes is common in the U.S.
Our industry has had a profound effect on population shifts, particularly in hot climates. Occupants in our buildings are now more comfortable, healthier, and more productive than they once were, thanks to improvements in our equipment and system designs.
These improvements have been brought on by a number of factors including technical, market changes, energy and environmental concerns, and political decisions.
Regardless of the reason for the changes, they will continue to occur and we have an obligation to direct those changes for both the benefit of our clients and our future.
Learning from the Past: Trends indicate that there continues to be an increase in demand for air-conditioning and with that comes a need for new technology. Let us review that trend.
Records show that central heating existed as long ago as the third century BC. Similarly, various techniques have been used to enhance ventilation in buildings. An article in the ASHRAE Journal describes an innovative design to enhance ventilation in the Natural History Museum, London, constructed in 1873. Cooling for comfort also had early beginnings. In the eighth century a Baghdad caliph had snow packed between walls of his villa for summer cooling. These are certainly unique examples but do not demonstrate the present impact of HVAC on the general public.
Although central cooling in office buildings existed as early as 1928 in the U.S., it was too expensive for the typical homeowner. After World War II, air-conditioning for comfort became increasingly popular. Whereas in the past, buildings had operable windows with awnings for shade, high ceilings, and possibly portable fans for cooling, the entire architecture of buildings began to change as air-conditioning became more prevalent.
Since 1940, eight of the 10 fastest growing cities in the U.S. are located in the Southeast and Southwest parts of the country. This is the direct result of air-conditioning.
"Stay Cool! Air Conditioning America" is an exhibit that opened May 1, 1999, at the National Building Museum in Washington, DC, USA. The exhibit shows the growth and impact of air-conditioning in the U.S. The exhibit will remain open through January 2, 2000.
Today air-conditioning is a way of life in the U.S. According to the Air-Conditioning and Refrigeration Institute (ARI), nearly 50% of all U.S. homes have air-conditioning and in 1996, 81% of all new homes constructed were equipped with central air-conditioning.
Will this exponential growth in the use of air-conditioning continue? Will other regions of the world see similar growth? It is the author?s opinion that growth will occur. However, the rate of that growth will depend on a number of variables.
The HVAC Market: Trends would indicate that the HVAC industry is responding to a robust market and that the market is significantly influenced by a concern for energy and the environment. Advancements in technology are responding to those concerns.
According to ARI, the value of shipments by U.S. HVAC manufacturers exceeded $28 billion U.S. in 1996. With 52,000 CFC chillers yet to be replaced in the U.S. alone, there remains a large market for new chillers, new technology, and new opportunities for the HVAC industry. In 1998 the U.S. manufactured 7558 non-CFC chillers for use in the U.S. and abroad. ARI indicates that the new, non-CFC chillers will be 40 percent more efficient than the CFC units installed 20 years ago. With less energy consumption comes lower CO2 emissions from electrical generating plants.
The U.S. Environmental Protection Agency predicts that by the year 2000, 44 percent of the CFC chillers that existed in the early 90?s will be replaced or converted. As a result, energy consumption will be reduced by 7 billion-kilowatt hours/year compared to that before replacement began. Similar improvements in residential, unitary air-conditioners can be seen in figure 1.
Figure 1: Shipment-Weighted Seasonal Energy Efficiency Ratios of Unitary Air-Conditioners (Less than 65,000 BTUH)
Sales in unitary equipment increased 16 percent in 1998 over the previous year.
Influences on HVAC Applications: Buildings have a significant impact on our global resources. ARI reports that in the U.S., 5.5 quads of energy are consumed in commercial buildings each year. Comfort cooling and refrigeration account for the largest portion of this (48%). Overall, buildings in the U.S. consume about 35% of the country?s total energy consumption.
As scientists, engineers, and technicians, we tend to feel that advances in the industry are primarily in response to advances in technology and a consumer demand for that technology. Technology is indeed important but much of the change in our industry is in reaction to other influences. The following is a description of some of these influences.
Energy: Few doubt that the energy we presently use is finite. The engineer who designs or operates equipment and systems has a commitment to minimizing energy use for the long-term benefit of humanity, as well as to save costs for his or her client or employer. In the U.S. the primary driver for energy conservation is not necessarily the finality of the source but the cost savings. Therefore operating costs are major influence in the adoption of new technology.
Energy supplies also have a strong political influence, not only between producing and consuming countries but also within countries where distribution inequities, taxing authority, and other political issues can influence policies that have little or no technical basis. The national security of a country may be dependent on a reliable flow of energy and therefore decisions regarding its use and availability may or may not directly impact equipment and system design.
We can anticipate that energy efficiency will continue to play a dominant role in our designs. We should not assume that we must sacrifice comfort for the sake of energy. Our challenge is to provide comfort while at the same time conserving energy.
Environment: The environment has possibly had more influence on HVAC technology than has energy. The environment will continue to impact our industry into the foreseeable future.
Ozone depletion is a global issue that is still being resolved. Developing countries are still permitted to produce CFC?s and are doing so in record volume. Illegal imports of CFC?s to the U.S. and other countries are a continuing concern. Much of the illegal imports are virgin CFC?s.
Likewise, local governments or groups of governments that attempt to ignore the Montreal Protocol cause major disruptions in the planned phaseout of refrigerants. For example attempts to accelerate the phaseout of HCFC?s will ultimately have damaging effects on our environment. As Ted Rees, President of ARI explains, early phaseout of HCFC?s will encourage use of CFC?s, particularly in developing countries, because HCFC alternatives are threatened with premature phaseout. In addition, trade barriers will negatively effect our industry,globally, without a benefit to society.
Policies regarding climate change have also directly impacted our industry. As we design and operate more energy-efficient equipment and systems, we use less energy, energy that, in many cases, comes from burning CO2-producing fossil fuels.
An interesting anomaly resulting from climate change is the new design conditions that are evolving for buildings as climate zones shift.
Like energy, the environment will continue to impact our industry. Fortunately our industry has proven that it can respond in a timely way. As we developed new, environmentally friendly products, those products are also more energy efficient. Each of us has an obligation to adopt these new technologies and support research that will help our industry meet the challenges of the future.
Human Factors: Worker productivity will become a significant factor in the way we design, install and operate our environmental control systems. Annual energy costs for an office building in the U.S. is approximately 45 to 90 Nlg/m2/year. Maintenance and other building and operating costs are similar. The cost to rent or own the property is approximately 225 to 900 Nlg/m2/yr. The total cost of personnel who occupy that building ranges from 4500 to 9000 Nlg/m2/yr. The point here is that although the cost of energy can and should be minimized, it should not be done at the expense of the productivity of the worker. Safety, health, comfort, and productivity are certainly influenced by the HVAC system. Air quality, noise, temperature, humidity control, and, in some cases, radiant heat transfer are all controllable variables. As important as good design is, it is equally important that the system be operated to assure a quality environment.
Beyond the immediate impact on the occupant, the level of control of the environment is also somewhat governed by occupant expectations. For example, in the U.S. occupants dress for indoor conditions that will be somewhat uniform regardless of exterior conditions. Whereas in some countries, this level of control may not be expected, particularly with regards to air-conditioning, in the U.S. temperature control has a major impact on occupant satisfaction.
As we better understand the impact of the environment on worker productivity, we will see an increased use of individual environmental control systems. Here each occupant will be able to select his or her preferred dry bulb temperature, air velocity, and possibly radiant and wet bulb temperature. Some systems will even provide a white noise generator that is under the control of the occupant.
Political: Adoption of building standards will increase. Whereas standards based on sound technical information and decisions are usually of benefit to a global society, those that have political overtones, particularly those that create a protectionism of local commerce, have a negative effect on those outside as well as inside the country.
The dialogue between ISO, CEN, and other multinational standard writing bodies is both commendable and productive. As engineers, we must continue to support the creation of standards based on a consensus of the industry and help avoid undue political influence. The sharing of knowledge through conferences such as this, scholarly publications, and cooperative activities of technical societies will contribute to technical rather than political-based standards.
We can anticipate that global standards for design of equipment and systems will increase. This should not necessarily be interpreted as negative or restrictive to our designs because, if the standards are based on sound technical information, they will provide the collective knowledge of engineers from throughout the world.
Societal: The engineer, scientist, and technician can make a major contribution toward satisfying the goal to conserve energy and to minimize the impact of our industry on the environment. He or she also has an obligation to assure that an interest in sustainability continues.
A growing societal ethic exists for protecting our environment and extending the availability of our natural resources. "Green Buildings" and sustainability are in-vogue terms at the moment. It is the author?s observation that this ethic is particularly strong in northern European countries. Although countries that have only limited or no domestic sources of energy have reasons of national security to be energy conscious, the commitment of the general public in many of those countries goes well beyond national security issues.
Communication: As engineers, we have an obligation to verify that the information we use whether received verbally, in print or on the Web is sound in principle and applicable to our client?s need.
Instant global communication has become commonplace, particularly in developed countries. As the author prepared for this conference, virtually all of the communication with TVVL was via the Internet. Similarly, engineers are regularly transmitting plans and specifications for new equipment and systems. We can now be interactive in real-time with engineers in multiple locations throughout the globe, while we work simultaneously on the same drawing, set of plans, or document. Visual communication via computer desktop video allows us to converse face to face. What impact will this have on our industry? It will be significant and totally positive. We can now instantly share information regardless of our location. We can draw on the knowledge of individuals throughout the globe as we design and operate systems for the comfort and health of our building occupants.
In addition, the Internet gives us access to a vast array of current technology that was previously unavailable. Geographic location is no longer an issue as we access the World Wide Web.
Looking Ahead: Conferences such as this one sponsored by TVVL will help disseminate new technology. All of us have an obligation to our profession and a global society to share our knowledge by contributing to the literature, supporting research, writing standards, and encouraging students to pursue our field of engineering.
It is impossible to predict the impact of technologies presently under development. For example, systems that do not rely on vapor compression such as desiccant cooling, thermoacoustic and magnetic refrigeration, and even older technologies like thermoelectric or vortex cooling may all have significant effects on our designs in the future, particularly as there becomes an increased emphasis on personal climate control.
It may be easier to accurately predict the effect of improvements in more traditional technologies, such as advances with natural and flammable refrigerants. Both Europe and North America are experiencing exponential growth in the use of natural refrigerants, particularly ammonia. The rate of growth in the use of flammable refrigerants is somewhat more difficult to predict. Adoption of ISO 5149, "Mechanical Refrigerating Systems Used for Cooling and Heating-Safety Requirements," will likely help increase the use of flammable refrigerants once thought to be unsafe.
Whereas in the recent past we experienced significant changes in air handling system designs ranging from variable air volume to displacement ventilation, it is the author?s prediction that innovations in computer-based control systems will have an equally dramatic effect on new designs. For example, the advent of fuzzy logic controllers which control a system to maintain a comfort zone or envelope rather than a single point or dead-band will have a significant impact on the equipment we select and the systems that deliver the conditioning fluid such as water or air.
Regardless of the equipment or controls used, it is the author?s opinion that we will definitely see an increase in the integration of the environmental control systems and the building structure. An increasingly popular terminology in our industry is "the building is a system." The communication between the architectural profession and the engineering profession will increase with division of responsibility becoming more integrated.
I also anticipate that we will see a renewed emphasis on our knowledge of human factors. A wealth of information exists on how we respond to the thermal environment, yet humans are the most complex part of the HVAC system. As we better understand the cause and effect of indoor air quality, the interaction with noise, light, air velocity and other environmental variables on humans, the better our design will be for environmental control systems.
Specialty environments will also take on increased importance. For example, special needs in a variety of medical facilities, facilities for the aging, manufacturing, and confinement housing for food animals will all present new challenges for our profession.
Preparing for the Future: Your value as an engineer is in what you know and your ability to apply that knowledge. As soon as your knowledge is less than state-of-the-art, your value to your client and employer declines.
We are in a dynamic profession. It is virtually impossible to keep current by merely continuing to use the same solutions to problems or to depend totally on our own innovative ability. We must be proactive in learning about new technologies throughout our entire career. In addition, we have an obligation to our profession to share our knowledge with others.
Again, electronic communication gives us the tool needed to share information globally. I predict that the future of our industry will be as dependent on lifelong learning as it is on the development of new technology.
Virtual electronic classrooms are here today. We need not wait for the future. ASHRAE President George Jackins set the establishment of the ASHRAE Learning Institute as one of his goals. His vision for this institute is to provide an opportunity for engineers around the globe to share knowledge regardless of their locations, time differences, and political boundaries.
ASHRAE will be making a considerable investment in the institute in order to serve our members, as well as share opportunities with other societies and individuals in our field.
It has long been the author?s position that virtually everyone in our industry has some knowledge from which the rest of us could benefit. The ASHRAE Learning Institute will help us share that knowledge.
Beyond ASHRAE, every technical society affiliated with the HVAC industry such as TVVL, will be increasing its emphasis on the transfer of knowledge. Only you, the engineering practitioner, will determine what knowledge is transferred and the method by which it is shared.
Conclusion: The rate of change in our industry will be exponential. Some changes will be caused by improvements in technology whereas others will be the result of influences outside our immediate control. As engineers, we have an obligation to be proactive in encouraging changes that are of benefit to the society we serve. This in turn will have direct benefit to our industry and to each of us individually.
You can be part of that positive change by sharing your knowledge with other engineers through publications, serving with standard writing organizations and participating in technical societies.
We are a "people-oriented" profession. Our designs have a direct impact on the people who occupy our buildings. We will continue to discover ways to assure their comfort and health, while reducing our impact on the environment and natural resources.
Changes will occur and for the better. Our vision for our industry can be fulfilled as we take action through our contributions to the technology of HVAC.
Downloadable software- cheap oem software.
Modern furniture- Modern bedroom furniture
|Ductless split air conditioning offer higher efficiency and reduced noise without a large hole in the wall or an open window. By separating compressor and condenser fan from indoor blower, the noisiest components are outside and away from the room. The indoor part of the ductless air conditioner has remote control capabilities and a timer to cycle the system only when needed. |
Since mini split air conditioners have no ducts, they avoid energy losses associated with ductwork of central forced air AC systems. Duct losses can account for a significant portion of energy consumption for space conditioning, especially if the ducts are in a unconditioned space such as an attic.
Ductless air conditioning offers Higher Efficiency vs. window air conditioning, less noise, and no costly ductwork.