9a. Home Heating Systems

Heating Systems EGEE 102

Energy Conservation and Environmental Protection Heating Systems Some hot water systems circulate water through plastic tubing in the floor, called radiant floor heating. http://www.eren.doe.gov/erec/factsheets/geo_heatpumps.html#sidebar notes EGEE 102 EGEE 102- S. Pisupati

Electric Heating Systems Resistance heating systems Converts electric current directly into heat usually the most expensive Inefficient way to heat a building Heat pumps Use electricity to move heat rather than to generate it, they can deliver more energy to a home than they consume Most heat pumps have a COP of 1.5 to 3.5. All air-source heat pumps (those that exchange heat with outdoor air, as opposed to bodies of water or the ground) are rated with a "heating season performance factor" (HSPF) EGEE 102

Geothermal Heat Pumps They use the Earth as a heat sink in the summer and a heat source in the winter, and therefore rely on the relative warmth of the earth for their heating and cooling production. Additional reading http://www.eren.doe.gov/erec/factsheets/geo_heatpumps.html#sidebar EGEE 102

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Geo Exchange Heat pump system Movie EGEE 102

World’s Largest Heat Pump The Galt House East Hotel and Waterfront Office Buildings in Louisville, Kentucky, use a 4,700 ton GHP system to meet the heating and cooling needs of the complex. The 750,000-square-foot (70,000 square meter) Galt House East Hotel, completed in 1984, uses a 1,700-ton GHP system, which cost $1,500 per ton to install http://www.eren.doe.gov/geothermal/geobasics.html http://www.nrel.gov/data/pix/searchpix.cgi?getrec=3297896&display_type=verbose EGEE 102

This house in Aurora, Colorado, uses a geothermal heat pump system that will provide al the heating, cooling, and hot water needs. For a home of 1,500 square feet with a good building envelope and a geothermal heat pump, energy costs are about $1 a day. EGEE 102

Cost Comparison, Gwinnet, GA Heating and Cooling Components 3-ton Addison heat pump, 15 kW auxiliary heat Closed loop Central thermostat Installation Costs $4,700 increment over comparable system $3,600 indoor hard costs $2,766/ton $1,800/house incentive from Jackson EMC Operating Costs (air source/water source) Heating $307/$211 Cooling $252/$230 Water heating $270/$136 Annual total $1,073/$577 5.84-year payback to recover $2,900 EGEE 102

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Benefits of a GHP System Energy Conservation and Environmental Protection Benefits of a GHP System Low Energy Use Free or Reduced-Cost Hot Water Year-Round Comfort Low Environmental Impact Durability Reduced Vandalism Zone Heating and Cooling Low Maintenance Low Energy Use The biggest benefit of GHPs is that they use 25-50% less electricity than conventional heating or cooling systems. This translates into a GHP using one unit of electricity to move three units of heat from the earth. According to a report by Oak Ridge National Laboratory, statistically valid findings show that the 4,003-unit GHP retrofit project at Fort Polk, Louisiana, will save 25.8 million kilowatt-hours (kWh) in a typical meteorological year, or 32.5% of the pre-retrofit whole-community electrical consumption. This translates to an average annual savings of 6,445 kWh per housing unit. In addition, 100% of the whole-community natural gas previously used for space conditioning and water heating (260,000 therms) will be saved. In housing units that were all-electric in the pre-retrofit period, the GHPs were found to save about 42% of the pre-retrofit electrical consumption for heating, cooling, and water heating. Free or Reduced-Cost Hot Water Unlike any other heating and cooling system, a geothermal heat pump can provide free hot water. A device called a "desuperheater" transfers excess heat from the heat pump's compressor to the hot water tank. In the summer, hot water is provided free; in the winter, water heating costs are cut roughly in half. Year-Round Comfort While producing lower heating bills, geothermal heat pumps are quieter than conventional systems and improve humidity control. These features help explain why customer surveys regularly show high levels of user satisfaction, usually well over 90 percent. Design Features Geothermal heat pump systems allow for design flexibility and can be installed in both new and retrofit situations. Because the hardware requires less space than that needed by conventional HVAC systems, the equipment rooms can be greatly scaled down in size, freeing space for productive use. And, geothermal heat pump systems usually use the existing ductwork in the building and provide simultaneous heating and cooling without the need for a four-pipe system. Improved Aesthetics Architects and building owners like the design flexibility offered by GHPs. Historic buildings like the Oklahoma State Capital and some Williamsburg structures use GHPs because they are easy to use in retrofit situations and easy to conceal, as they don't require cooling towers. GHP systems eliminate conventional rooftop equipment, allowing for more aesthetically pleasing architectural designs and roof lines. The lack of roof top penetrations also means less potential for leaks and ongoing maintenance, and better roof warranties. In addition, the aboveground components of a GHP system are inside the building, sheltering the equipment both from weather-related damage and potential vandalism. Low Environmental Impact Because a GHP system is so efficient, it uses a lot less energy to maintain comfortable indoor temperatures. This means that less energy—often created from burning fossil fuels—is needed to operate a GHP. According to the EPA, geothermal heat pumps can reduce energy consumption—and corresponding emissions—up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment. Low Maintenance According to a study completed for the Geothermal Heat Pump Consortium (GHPC), buildings with GHP systems had average total maintenance costs ranging from 6 to 11 cents per square foot, or about one-third that of conventional systems. Because the workhorse part of the system—the piping—is underground or underwater, there is little maintenance required. Occasional cleaning of the heat exchanger coils and regularly changing the air filters are about all the work necessary to keep the system in good running order. Zone Heating and Cooling These systems provide excellent "zone" space conditioning. With this, different areas of the building can be heated or cooled to different temperatures simultaneously. For example, GHP systems can easily move heat from computer rooms (which need constant cooling) to the perimeter walls for winter heating in commercial buildings. School officials like the flexibility of heating or cooling just auditoriums or gymnasiums for special events—rather than the entire school. Durability Because GHP systems have relatively few moving parts, and because those parts are sheltered inside a building, they are durable and highly reliable. The underground piping often carries warranties of 25 to 50 years, and the GHPs often last 20 years or more. Reduced Vandalism GHPs usually have no outdoor compressors or cooling towers, so the potential for vandalism is eliminated. EGEE 102 EGEE 102- S. Pisupati

Solar Heating and Cooling Most American houses receive enough solar energy on their roof to provide all their heating needs all year! Active Solar Passive Solar EGEE 102

Passive Solar A passive solar system uses no external energy, its key element is good design: House faces south South facing side has maximum window area (double or triple glazed) Roof overhangs to reduce cooling costs Thermal mass inside the house (brick, stones or dark tile) EGEE 102

Passive Solar Deciduous trees on the south side to cool the house in summer, let light in in the winter. Insulating drapes (closed at night and in the summer) Greenhouse addition Indirect gain systems also such as large concrete walls to transfer heat inside EGEE 102

Passive Solar Heating EGEE 102

Source: Global Science, Energy Resources Environment EGEE 102 Source: Global Science, Energy Resources Environment

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Active Solar Heating Flat plate collectors are usually placed on the roof or ground in the sunlight. The sunny side has a glass or plastic cover. The inside space is a black absorbing material. Air or water is pumped (hence active) through the space to collect the heat. Fans or pumps deliver the heat to the house EGEE 102

Active Solar Heating EGEE 102

Flat Plate Collector Solar Collectors heat fluid and the heated fluid heats the space either directly or indirectly EGEE 102

Efficiency of Furnace The "combustion efficiency" gives you a snapshot in time of how efficient the heating system is while it is operating continuously The "annual fuel utilization efficiency" (AFUE) tells you how efficient the system is throughout the year, taking into account start-up, cool-down, and other operating losses that occur in real operating conditions. AFUE is a more accurate measure of efficiency and should be used if possible to compare heating systems. EGEE 102

Efficiencies of Home Heating EGEE 102

Tips (Individual) to Save Energy and Environment 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. EGEE 102

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. EGEE 102

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. EGEE 102