Heating - Heating And Cooling Your Home If you own a typical U.S. home, heating and air-conditioning account for about 56% of your energy use. Heating is the largest energy expense in most homes, accounting for almost two-thirds of annual energy bills in colder areas of the country. What's more, heating and cooling systems in the United States together emit over a billion tons of carbon dioxide (CO2) and about 12% of the sulfur dioxide and nitrogen oxides emitted by the nation, the chief ingredients in acid rain. Reducing energy use for heating is the single most effective way to reduce your home's contribution to global environmental problems. You can substantially reduce this energy use by adding efficient controls and by making full use of solar energy. If your heating system or air-conditioner is old or inefficient, it may also be cost effective to replace it with a newer high-efficiency design.
No matter what kind of heating, ventilation, and air-conditioning system you have in your house, you can save money and increase comfort by properly maintaining and upgrading your equipment. But remember, an energy efficient furnace alone will not have as great an impact on your energy bills as using the whole-house approach. By combining proper equipment maintenance and upgrades with appropriate insulation, weatherization, and thermostat settings, you can cut your energy bills and your pollution output in half.
HVAC (heating, ventilating, and air-conditioning) refers to the equipment, distribution network, and terminals that provide either collectively or individually the heating, ventilating, or air-conditioning processes to a building. HVAC systems provide:
* Heating
* Cooling
* Air Handling, Ventilation, and Air Quality
HVAC accounts for 40% to 60% of the energy used in U.S. commercial and residential buildings. This represents an opportunity for energy savings using proven technologies and design concepts. HVAC systems have a significant effect on the health, comfort, and productivity of occupants. Issues like user discomfort, improper ventilation, and poor indoor air quality are linked to HVAC system design and operation and can be improved by better mechanical and ventilation systems. In existing buildings, envelope upgrades are often necessary to maximize comfort and energy efficiency, such as reducing envelope leakage.
The best HVAC design considers all the interrelated building systems while addressing indoor air quality, energy consumption, and environmental benefit. Optimizing the design and benefits requires that your mechanical system designer and your architect address these issues early in the schematic design phase and continually revise subsequent decisions throughout the remaining design process. It is also essential that you implement well-thought-out commissioning processes and routine preventative maintenance programs. This is good advice for both new and retrofit applications. 
| Figure 13: Household Heating Systems: Although there are several different types of fuels available to heat our homes, about half of us use natural gas. |
To optimize the selection of efficient, cost-effective mechanical and ventilation systems, perform an energy analysis early in the process, during the schematic design phase. Several design and analysis software programs can provide building simulations on an hourly basis to predict the energy behavior of the building's structure, air-conditioning system, and central plant equipment.
Evaluating your HVAC needs or opportunities will be greatly aided if you are familiar with integrated building design concepts. Specifically, you might wish to refer to the Passive Solar Design section, Building Envelope Components section, Active Solar Heating Systems section, and the Photovoltaics section. If you are constructing a new building, following the Use The Whole-Building Design Approach section will enable you to reduce your HVAC requirements. This design approach can save lots of money and energy by reducing the size requirements of your HVAC system and its energy demand, while still meeting comfort requirements.
Efficient control of your home's heating and cooling systems saves energy and money. For instance, programmable thermostats save energy by turning down the heat at night or when your house is usually not occupied. For houses with central air-conditioning, programmable thermostats can also allow the house to heat up when it is unoccupied. This can be particularly effective if your home is unoccupied for large periods of the day. You can save energy without any loss of comfort, because the thermostat can be programmed to return temperatures to the comfort zone during hours when you're home and awake in the morning and evening.
Programmable Thermostats: You can save as much as 10% a year on your heating and cooling bills by simply turning your thermostat back 10% to 15% for 8 hours. You can do this automatically without sacrificing comfort by installing an automatic setback or programmable thermostat. | Figure 14: Using a programmable thermostat, you can automatically turn down your heat at night or when you are not at home. | 
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Using a programmable thermostat, you can adjust the times you turn on the heating or air-conditioning according to a pre-set schedule. As a result, you don't operate the equipment as much when you are asleep or when the house or part of the house is not occupied. (These thermostats are not meant to be used with heat pumps.) Programmable thermostats can store and repeat multiple daily settings (six or more temperature settings a day) that you can manually override without affecting the rest of the daily or weekly program. When shopping for a programmable thermostat, be sure to look for the ENERGY STAR(r) label. See Automatic And Programmable Thermostats section.
Zone heating and cooling is also used in some homes. This allows you to reduce the heating and cooling to an unused part of the home, and can substantially reduce your energy bills. Depending on your home's design and your heating and cooling system, it may be possible to retrofit your home to zone heating and cooling. Check with a local heating and cooling contractor to see if this option is practical for you.
Ducts: One of the most important systems in your home, though it's hidden beneath your feet and over your head, may be wasting a lot of your energy dollars. Your home's duct system, a branching network of tubes in the walls, floors, and ceilings, carries the air from your home's furnace and central air-conditioner to each room. Ducts are made of sheet metal, fiberglass, or other materials.
Unfortunately, many duct systems are poorly insulated or not insulated properly. Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating and cooling bills. Insulating ducts that are in unconditioned spaces is usually very cost effective. If you are buying a new duct system, consider one that comes with insulation already installed. See Ductwork section.
Heat Pumps: If you use electricity to heat your home, consider installing an energy efficient heat pump system. Heat pumps are the most efficient form of electric heating in moderate climates, providing three times more heating than the equivalent amount of energy they consume in electricity. There are three types of heat pumps: air-to-air, water source, and ground source. They collect heat from the air, water, or ground outside your home and concentrate it for use inside. Heat pumps do double duty as a central air-conditioner. They can also cool your home by collecting the heat inside your house and effectively pumping it outside. A heat pump can trim the amount of electricity you use for heating as much as 30% to 40%. See Heat Pumps section.
Solar Heating and Cooling: Using passive solar design techniques to heat and cool your home can be both environmentally friendly and cost effective. Passive solar heating techniques include placing larger, insulated windows on south-facing walls and locating thermal mass, such as a concrete slab floor or a heat-absorbing wall, close to the windows. In many cases, you can cut your heating costs by more than 50% compared to the cost of heating the same house that does not include passive solar design.
Passive solar design can also help reduce your cooling costs. Passive solar cooling techniques include carefully designed overhangs, windows with reflective coatings, and the use of reflective coatings on exterior walls and the roof. However, a passive solar house also requires careful design and site orientation, which depend on the local climate. So, if you are considering passive solar design for new construction or a major remodeling, you should consult an architect familiar with passive solar techniques. See Passive Solar Heating section.
Fireplaces: When you cozy up next to a crackling fire on a cold winter day, you probably don't realize that your fireplace is one of the most inefficient heat sources you can possibly use. It literally sends your energy dollars right up the chimney along with volumes of warm air. A roaring fire can exhaust as much as 24,000 cubic feet of air per hour to the outside, which must be replaced by cold air coming into the house from the outside. Your heating system must warm up this air, which is then exhausted through your chimney. If you use your conventional fireplace while your central heating system is on. See Fireplaces and Wood Heating section.
Gas and Oil Heating Systems: If you plan to buy a new heating system, ask your local utility or State energy office for information about the latest technologies available to consumers. They can advise you about more efficient systems on the market today. For example, many newer models incorporate designs for burners and heat exchangers that result in higher efficiencies during operation and reduce heat loss when the equipment is off. See How To Buy An Energy Efficient Gas Furnace section.
Air-conditioners: It might surprise you to know that buying a bigger room air-conditioning unit won't necessarily make you feel more comfortable during the hot summer months. In fact, a room air-conditioner that's too big for the area it is supposed to cool will perform less efficiently and less effectively than a smaller, properly sized unit. This is because room units work better if they run for relatively long periods of time than if they are continually, switching off and on. Longer run times allow air-conditioners to maintain a more constant room temperature.
Sizing is equally important for central air-conditioning systems, which need to be sized by professionals. If you have a central air system in your home, set the fan to shut off at the same time as the cooling unit (compressor). In other words, don't use the system's central fan to provide circulation, but instead use circulating fans in individual rooms. See Air-Conditioning section. Heating And Cooling Tips
* Set your thermostat as low as is comfortable in the winter and as high as is comfortable in the summer.
* Clean or replace filters on furnaces once a month or as needed.
* Clean warm-air registers, baseboard heaters, and radiators as needed; make sure they're not blocked by furniture, carpeting, or drapes.
* Bleed trapped air from hot-water radiators once or twice a season; if in doubt about how to perform this task, call a professional.
* Place heat-resistant radiator reflectors between exterior walls and the radiators.
* Use kitchen, bath, and other ventilating fans wisely; in just 1 hour, these fans can pull out a houseful of warmed or cooled air. Turn fans off as soon as they have done the job.
* During the heating season, keep the draperies and shades on your south-facing windows open during the day to allow sunlight to enter your home and closed at night to reduce the chill you may feel from cold windows. During the cooling season, keep the window coverings closed during the day to prevent solar gain.
* Close an unoccupied room that is isolated from the rest of the house, such as in a corner, and turn down the thermostat or turn off the heating for that room or zone. However, do not turn the heating off if it adversely affects the rest of your system. For example, if you heat your house with a heat pump, do not close the vents-closing the vents could harm the heat pump.
* Select energy efficient equipment when you buy new heating and cooling equipment. Your contractor should be able to give you energy fact sheets for different types, models, and designs to help you compare energy usage. Look for high Annual Fuel Utilization Efficiency (AFUE) ratings and the Seasonal Energy Efficiency Ratio (SEER). The national minimums are 78% AFUE and 10 SEER.
* Look for the ENERGY STAR(r) and EnergyGuide labels. ENERGY STAR(r) is a program of the U.S. Department of Energy (DOE) and the Environmental Protection Agency (EPA) designed to help consumers identify energy efficient appliances and products. |
