Heating_Cooling

A pleasant climate Heating and ventilation technology ensure well-adjusted and allergy-free living.

UNITS / TERMS:

 Heating Degree-Days (HDD) are used to measure the severity of winter or heating energy conditions. Using a reference temperature of 65 F, degree days are determined by the difference in the mean daily temperature and the reference temperature. For example, a day with 50 F mean temperature has 15 HDD (65 50 = 15). The annual Heating Degree Days are the sum of the degree days over a calendar year. 

 

 Annual Fuel Utilization Efficiency (AFUE) - The AFUE is the most widely used measure of a furnace's heating efficiency. It measures the amount of heat actually delivered to a house compared to the amount of fuel that is supplied to the furnace. Thus, a furnace that has an 80% AFUE rating converts 80% of the fuel to heat -- the other 20% is lost out of the chimney and elsewhere. AFUE is commonly expressed as a percentage. Energy Star qualified furnaces have an AFUE rating of 90% or greater, making them about 15% more efficient than standard models.

 

 Seasonal Energy Efficiency Ratio (SEER) The SEER is the most widely used measure of a central air conditioners energy efficiency. Air conditioners manufactured after January 23, 2006 must achieve a SEER of 13 or higher, which reflects a 30% increase in the federal minimum efficiency level. 

 

 Electric Air-Source Heat Pumps (ASHPs) - Electric air-source heat pumps, often used in moderate climates, use the difference between outdoor air temperatures and indoor air temperatures to heat and cool a space. ASHPs remove excess heat from indoors and release it outdoors. Energy Star ASHPs use 20% less energy than conventional models and have higher heating season performance factor (HSPF) ratings. HSPF ratings measure the heating efficiency of heat pumps.

 

 Geothermal Heat Pumps (GHPs) - Geothermal heat pumps are similar to ordinary heat pumps, but use the ground instead of outside air to provide heating, air conditioning, and in most cases, hot water. Because GHPs use the earth's natural heat, they are among the most efficient heating and cooling technologies currently available. Energy Star GHPs use 30% less energy and include water heating capabilities. Although typically more expensive initially, GHPs quickly payback the homeowner in significant energy cost savings.

Energy Star: A Guide to Energy-Efficient Cooling and Heating

Kansas State University: Selecting a Home Heating System

 Heating Degree-Days (HDD) can be found on the National Weather Service's Web site as a historical record of departures of average daily temperatures from a reference temperature of 65oF. Heating Degree Days per year provides a very useful estimate of how often a heating system will run and helps a homeowner estimate the costs of heating during a season. For example, a high annual average total HDD value for a particular location suggests a very cold climate.

 

 Residential heating systems should be appropriately sized, such that the home will not only be comfortable during the coldest weather, but comfortable in the hottest weather as well. Oversized equipment results in increased energy costs and high temperature swings during mild weather. Energy raters and HVAC specialists are in the best position to evaluate and make recommendations regarding the proper sizing of heating, ventilation, and air conditioning equipment.

 

 Heating and cooling a home costs the average homeowner about $600 a year -- nearly half the average home's total energy bill of $1,400.

Heating technologies include furnaces, boilers, air-source heat pumps, district heating and cooling, and ducts. Furnaces are the most common residential heating system in the United States. Furnaces typically run on gas, but sometimes on fuel oil or electricity. Heat delivery is through a duct system.

 

 Many humans are most comfortable at a relative humidity of 50%, plus or minus 10%. In the winter, air inside the house is cycled repeatedly past heating elements in heating systems, where the air gets drier and drier. As room air dries, people experience increasingly dry and itchy skin, dry eyes and mouth, chapped hands, static electricity and potentially a wide range of other discomforts. From an energy efficiency perspective, the dry air increases the rate of evaporation of body moisture from skin surfaces and this evaporation makes a person feel chilled. A normal reaction is to turn up the heat as one attempts to keep warm. The net result is that people burn extra fuel to maintain a higher room temperature, and the air becomes progressively drier. In order to maintain a comfortable room temperature in the winter, the strategy should be to add moisture to the air.

 

 Studies have shown that when humidity is maintained at around 50% in a living space, air conditioner thermostats may be set as much as 5 to 7 degrees (F) warmer while providing the same level of comfort to occupants. Since most air conditioners are electric, and most electricity is produced in central-station power plants, energy and pollution savings from reduced air conditioning are substantial.
 

CALCULATE SAVINGS

 Energy Star qualified furnaces have an AFUE rating of 90% or greater, making them about 15% more efficient than standard models. For Energy Star's Furnace Savings Calculator, go to: http://www.energystar.gov/ia/business/bulk_purchasing/bpsavings_calc/Calc_Furnaces.xls
 

 Boilers burn gas or fuel oil to heat water or steam that circulates through radiators, baseboards or radiant floor systems. Energy Star qualified boilers have an AFUE rating of 85% or greater and use about 10% less energy than standard boilers. For Energy Star's Boiler Savings Calculator, go to: http://www.energystar.gov/ia/business/bulk_purchasing/bpsavings_calc/Calc_Boilers.xls.

BACKGROUND FACTS

 Boilers burn gas or fuel oil to heat water or steam that circulates through radiators, baseboards or radiant floor systems. Energy Star qualified boilers have an AFUE rating of 85% or greater and use about 10% less energy than standard boilers.

 

 Cooling technologies include room air conditioners, central air conditioners, fans, evaporative coolers, shading, and mass applications. SEER is the measure of energy efficiency for central air conditioners and EER is the measure of energy efficiency for room air conditioners.

 Programmable thermostats allow homeowners to maximize energy savings without sacrificing comfort. Setting back the thermostat for as little as four hours a day can result in significant savings. Programmable thermostats can save approximately $100 a year. They work in conjunction with various heating and cooling systems and allow occupants to pre-set temperatures for various times during the week and weekend, whether they are at work, at home, or in bed sleeping.

 Planting shade trees in strategic positions is an attractive and effective way of cooling the home naturally. Shading can reduce inside temperatures by as much as 21oF (11oC).
 

 Homeowners can create natural cross-ventilation by opening windows and doors. Different parts of the home can be ventilated just by adjusting the size and location of the openings.
 

 Sealing air leaks in a home's envelope (the outer walls, ceiling, windows, and floors) can increase comfort and energy efficiency, while decreasing energy bills.

Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse: Automatic and Programmable Thermostats

Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse: Cooling Your Home with Fans and Ventilation

Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse: Cooling Your Home Naturally

Department of Energy's Energy Efficiency and Renewable Energy Clearinghouse: Energy-Efficient Air Conditioning