The materials from which a building is constructed, as well as the systems and appliances installed there, can dramatically affect the amount of energy that a building will consume over its lifetime. To help customers compare the potential impact of one to another, efficiency ratings have been devised for many building components and energy systems.
A variety of energy ratings now abound, which can be confusing to the consumers these ratings were intended to help. We will try here to end that confusion by explaining each of the ratings systems listed below in as simple a way as possible. Also included is a Glossary of Efficiency Terms.
The materials from which a building is constructed can have a marked impact on the structure’s efficiency. Materials that allow a lot of heat to pass through them lower the overall efficiency level of the building. Conversely, materials that resist a significant amount of heat transference can help ensure greater efficiency. The degree to which a building component (such as a window or wall system) transfers heat is referred to as its U-value. The ability of an individual material (for instance, glass, wood, metal) to resist heat transfer is called its R-value.
Appliances and Equipment
When referring to the efficiency of an appliance or energy system, we are actually talking about how much energy that system must use to perform a certain amount of work. The higher its energy consumption per unit of output, the less efficient the system is. For example, an air conditioner that requires 750 watts of electricity to provide 6,000 Btu of cooling will be less efficient than one that can provide the same amount of cooling for only 500 watts. The most common ratings applied to energy systems are EER and SEER for most central cooling systems; COP for some heat pumps and chillers; HSPF for heat pumps in their heating modes; and AFUE for gas furnaces and boilers.
For more detailed explanations of the efficiency terms mentioned above, select any of the underlined topics below.
Glossary of Efficiency Terms
AFUE (annual fuel utilization efficiency): an efficiency rating that measures the efficiency with which gas and other fossil-fuel-burning furnaces and boilers use their primary fuel source over an entire heating season. It does not take into account the efficiency with which any component of the system, such as a furnace fan motor, uses electricity. AFUE is expressed as a percentage that indicates the average number of Btu worth of heating comfort provided by each Btu worth of gas (or other fossil fuel) consumed by the system. For instance, a gas furnace with an AFUE of 80% would provide 0.8 Btu of heat for every Btu of natural gas it burned.
When comparing efficiencies of various gas furnaces, it is important to consider the AFUE, not the steady-state efficiency. Steady-state refers to the efficiency of the unit when the system is running continuously, without cycling on and off. Since cycling is natural for the system over the course of the heating season, a steady state doesn’t give a true measurement of the system’s seasonal efficiency. For instance, gas furnaces with pilot lights have steady-state efficiencies of 78% to 80%, but seasonal efficiencies B AFUEs B closer to 65%.
Virtually all gas forced-air furnaces installed in this area from the 1950s through the early 1980s had AFUEs of around 65%. Today, federal law requires most gas furnaces manufactured and sold in the U.S. to have minimum AFUEs of 78%. (Mobile home furnaces and units with capacities under 45,000 Btu are permitted somewhat lower AFUEs.) Gas furnaces and boilers now on the market have AFUEs as high as 97%
Air infiltration: the introduction, usually unintentional, of unconditioned outdoor air into a mechanically heated and/or cooled building. Air infiltration can occur through any opening in the home’s structure, including seams where walls meet other walls, window or door frames, or chimneys; holes where wires or pipes penetrate walls, floors or ceilings/roofs; and between the loose-fitting meeting rails of double-hung windows or a door bottom and door threshold. It is one of the major causes of unwanted heat gain and loss and personal discomfort in buildings.
Btu (British thermal unit): a measurement of the energy in heat. It takes one Btu of heat to warm one pound of water by 1° Fahrenheit. Btu can be used either to define an air conditioner’s cooling capacity (i.e., the number of Btu of heat that can be removed by the system) or a furnace’s heating capacity (i.e., the number of Btu of heat that can be supplied by the system).
Caulk: a substance used to seal air infiltration points between two immovable objects, such as where exterior or interior wall surfaces meet window or door frames and at corners formed by siding. Most caulks come in tubes and are applied with the use of a special caulk “gun.”
Compact fluorescent lamps (CFLs): a light “bulb” using fluorescent technology but designed to be used on many of the same fixtures traditionally used by standard incandescent “A” bulbs. They incorporate a small-diameter looped or swirled tube that is attached to a screw-in base. CFLs provide light levels comparable to 20- to 150-watt incandescent bulbs for 70% to 75% less energy. They also last 10 to 13 times longer than equivalent incandescent bulbs.
Conduction: the transfer of heat through solid objects such as glass, drywall, brick, and other building materials. The greater the difference between the outdoor and indoor temperatures, the faster conduction can occur and the more home a building can gain or lose.
Convection: the transfer of heat to or from a solid surface via a gas or liquid current. Where home heat loss and gain are concerned, heat convection is caused by air (gas) currents that carry heat from your body, furniture, interior walls and other warm objects to windows, floors, ceilings, exterior walls, and other cool surfaces.
COP(coefficient of performance): a measurement of a heat pump’s efficiency (in the heating mode) at a specific outdoor temperature – usually 47°F. A COP of 1 indicates that for each unit of energy being used, an equal amount of energy, in the form of heat) is being provided by the system. A heat pump with a COP of 3 would provide three times as much energy in heat as it consumes in electricity at an outdoor temperature of 47°F. COP is also sometimes used to measure the single temperature cooling efficiency of chillers.
This formula is stated:
Btu of heat produced at 47°F
Btu worth of electricity used at 47°
For instance, let’s assume a heat pump uses 4000 watts of electricity to produce 42,000 Btu per hour (Btu/hr) of heat when it is 47°F outside. To determine its COP, you would first convert the 4000 watts of electrical consumption into its Btu/hr equivalent by multiplying 4000 times 3.413 ( the number of Btu in one watt-hour of electricity). Then you would divide your answer — 13,648 Btu/hr — into the 42,000 Btu/hr heat output. This would show your heat pump to have a 47°F COP of 3.08. This means that, for every Btu of electricity the system uses, it will produce a little more than three Btu of heat when the outdoor temperature is 47°F.
The second formula is most frequently used to determine chiller efficiency. Using this calculation method, you would div 3.516 by the number of kilowatts (kW) per ton used by the system. This formula is stated:
For example, a chiller that consumes 0.8 kW per ton of capacity would have a COP of 4.4 (3.516 divided by 0.8). On the other hand, the COP of a new, more efficient chiller, using as little as 0.5 kW per ton, would be greater than 7 (3.516 divided by 0.5).
Daylighting: the technique of using natural light from windows, skylights and other openings to supplement or replace a building’s artificial lighting system. When applied properly, daylighting can reduce a facility’s lighting costs. When applied improperly, however, it can not only lead to inappropriate light levels but can also raise the building’s cooling costs by introducing high levels of solar heat into the interior of the building.
Dedicated fixture: a lighting apparatus that is designed specifically for use with a particular type of lamp (bulb). For example, the increasing popularity of CFLs has led to the development of a growing number of fixtures – including torchieres, table lamps, ceiling drums, and recessed canisters – dedicated solely for use with compact fluorescents.
EER (energy efficiency ratio): a measurement of the energy required by a cooling system as it attempts to maintain indoor comfort at a specific outdoor temperature – usually 95°F. The term EER is most commonly used when referring to window air conditioners and geothermal heat pumps. EER equals the number of Btu per hour worth of cooling provided at the specified outdoor temperature divided by the number of watts used to provide that level of cooling.
The formula for calculating EER is:
Btu/hr of cooling at 95°
watts used at 95°
For instance, if you have a window air conditioner that draws 1500 watts of electricity to produce 12,000 Btu per hour of cooling when the outdoor temperature is 95°, it would have an EER of 8.0 (12,000 divided by 1500). A unit drawing 1200 watts to produce the same amount of cooling would have an EER of 10 and would be more energy efficient.
Using this same example, you can see how efficiency can affect a system’s operating economy. First, you’ll need to determine the total amount of electricity — measured in kilowatt-hours — the unit will consume over a period of time. (A kilowatt-hour is defined as 1,000 watts used for one hour. This is the measure by which your monthly utility bills are calculated.) To do this, let’s assume you operate your 8 EER window air conditioner — drawing 1500 watts at any given moment — for an average of 12 hours every day during the summer. At this rate, it will use 18,000 watt-hours, or 18 kilowatt-hours (kWh) each day, leading to a total consumption of 540 kWh over the course of a 30-day month. At a summer electric rate of 6.34¢ per kWh, it would cost you $34.24 to operate that window air conditioner each month. At the same time, a 1200-watt, 10 EER system, consuming 14.4 kilowatt-hours per day and 432 kWh per month, would cost you $27.39, a 20% savings over the less efficient model.
Efficiency: the degree to which a certain action or level of work can be effectively produced for the least expenditure of effort or fuel. For instance, a light bulb that uses 15 watts of electricity to produce 900 lumens of light would operate with much greater efficiency than one that required 60 watts to produce the same light level.
HSPF (heating seasonal performance factor): a measurement of an all-electric air-to-air heat pump’s efficiency (in the heating mode) over an entire season. HSPF is calculated by dividing the total number of Btus of heating provided over the entire season by the total number of watt-hours required to operate the system over the season.
The formula is written:
Btu of heat produced over the heating season
watt-hours of electricity used over the heating season
Most heat pumps installed in Springfield today have HSPFs in the 7.0 to 8.0 range, meaning they operate with seasonal efficiencies of anywhere from 205% to 234%. (To convert the HSPF number into a percentage, you just divide the HSPF by 3.414, the number of Btu in one watt-hour of electricity.) That means that, for every Btu-worth of energy they use over the entire heating season, these systems will put out anywhere from 2.05 to 2.34 Btu of heat. Compare this to electric furnaces, which have nominal efficiencies of 100% (for each Btu worth of electricity, they put out one Btu of heat), or new gas furnaces, which have efficiency ratings of about 80% to 97% (for each Btu worth of gas, they put out 0.8 to 0.97 Btu of heat).
NOTE: When comparing energy systems that use different primary fuel sources with different costs per Btu, it is important that you understand that higher operating efficiency is not necessarily equivalent to a better operating economy. Although an electric heat pump might work with greater efficiency than a gas furnace, it won’t necessarily be more economical to run due to the pricing difference between the two fuel sources.
Insulation: a product that inhibits conductive and convective heat transfer. Some materials are naturally better insulators than others because they contain more “dead air” pockets. These pockets of trapped gas help to slow the movement of heat. However, if processed properly, virtually any product, including glass, cotton, paper, and plastic, can be used to make insulation.
Internal Heat Gain: the accumulation of heat produced by a building’s energy systems and appliances and occupants. Depending on the number of occupants and the type and number of energy systems used during the day, it’s not unusual for internal heat gain to account for 20% of a home’s total summer cooling load.
Kilowatt (kW): 1000 watts.
Kilowatt-hour (kWh): 1000 watts used for one hour – or any combination of energy multiplied by time that is equivalent to that rate of electrical consumption, such as one watt used for 1000 hours, 10 watts used for 100 hours, or 50 watts used for 20 hours. For example, a 100-watt light bulb left on for five hours each day would consume one kWh every two days. Kilowatt-hour is the primary measure on which U.S. electric companies base most customer billing. CWLP residential customers pay an average of 5.5¢ to 6¢ per kWh of electricity used.
Low-e: refers to a material designed to reduce the amount of radiant heat that can be transferred through glass or other translucent window coverings. Low-e (which stands for low-emissivity) coatings or films have the ability to re-radiate a high percentage of heat back toward its source. In summer Low-E windows can be effective in reducing the amount of solar heat that can enter a house, and in winter they can reduce the amount of furnace-generated heat that can be lost to the outdoors.
Lumen: a unit of light given off by a light source. Lumen is the measurement used to compare the levels of illumination provided by different light sources.
Payback period: the amount of time it takes to achieve a full return on investment. For instance, if a high-efficiency air conditioner would cost you $300 more to purchase than a lower-efficiency model but would save you $100 a year in operating costs, your payback period on the extra $300 investment would be three years.
Radiation: a method of heat transfer in which heat is transmitted from surface to surface via infrared waves. Radiant heat warms the surfaces it touches without increasing the temperature of the air through which it travels. All warm bodies radiate infrared energy.
Return on investment (ROI): the annual rate at which an investment earns income. It is calculated by dividing the annual earnings by the investment. For instance, a bank savings account paying $3 per year per $100 investment has an ROI of 3% ($3 / $100). An efficiency investment’s ROI comes not from money paid to you, but rather from money saved by you on your energy bills.
R-value: a measurement of a material’s ability to resist heat transfer. Insulation products are rated according to the R-value. The higher its R-value, the greater the product’s ability to resist heat flow will be.
Some materials are more resistant to heat transfer than others, giving them higher R-values. One of the best ways to enhance the product’s R-value is to increase the amount of gas (including air) inside or immediately surrounding it. For instance, the glass of a single-pane window has virtually no R-value, but the thin film of air that normally exists on either side of the glass gives the window an R-value of about 0.83. Adding a second pane of glass and sealing the space between the panes will increase the thickness of one of the insulating gas layers, thereby more than doubling the window’s R-value.
Another example of how the presence of dead-air spaces affect a product’s R-value can be seen with wood. Hardwoods, like oak, typically have an insulating value of R-1 per inch of thickness. However, softer woods, such as pine, might have R-values twice as high due to their greater number of air-filled pores.
Products developed especially for the purpose of impeding unwanted heat transfer are called insulation. Insulation can be made of a variety of materials, including old newspapers and wood fibers, glass fibers, and synthetic foams. It can also come in a variety of configurations, including soft blankets, rigid boards, or fluffy granular loose-fill, but what they all have in common, is their abundance of air-filled pores or pockets.
The actual R-value of insulation products can vary greatly, depending on their composition and form. The least resistant and least common are perlite and vermiculite loose-fills, at R-2.2 to R-2.7 per inch of thickness; the most resistant are polyisocyanurate rigid boards, at R-7 per inch of thickness. Fiberglass blankets and cellulose loose-fills, two of the most common residential insulations have R-values of 3.1 to 3.7 per inch.
SEER (seasonal energy efficiency ratio): a measurement of how energy efficient a central cooling system can operate over the course of an entire cooling season. This term is most often applied to central air-to-air heat pumps (in the cooling mode) and air conditioners. SEER is expressed as the dividend of the number of Btu of cooling provided over the season divided by the total number of watt-hours the system consumes. Federal law requires all central split systems now made and sold in the United States to have minimum SEERs of 10. Effective January 2015, the minimum for most systems will increase to 14.
SEER is calculated based on the total amount of cooling (in Btu) the system will provide over the entire season divided by the total number of watt-hours it will consume:
seasonal Btu of cooling
seasonal watt-hours used
By federal law, every central split cooling system manufactured or sold in the U.S. today must have a seasonal energy efficiency ratio of at least 10.0.
Settled density: the amount (depth) of insulation remaining after it has had a chance to settle. This term is most often applied to loose-fill insulations—particularly those made of cellulose. To ensure loose-fill cellulose insulation will maintain its desired insulating value (r-value) once it has settled, you will need to install it to a depth that is 20% to 25% deeper than your settled density r-value actually calls for.
Solar Gain: heat that builds up inside a structure as a result of sunlight that enters through transparent or translucent surfaces, such as windows, and is converted to heat after striking other surfaces inside the building. In summer, solar gain can cause as much as 50% of the interior heat gain in a home.
Thermostat Setback: an intentional effort to control building energy consumption by manually or automatically controlling thermostat settings according to the amount of cooling or heat that is needed at any given time of the day or night.
U-value: the measurement of how readily heat can flow through glass, brick, drywall and other building materials. U-values, which are expressed in decimals(e.g., U-0.166), are the opposite of R-values. The higher the U-value, the less efficient the building material will be. The lower a material’s U-value, the higher its R-value will be.
To determine the R-value of a product for which the U-value is given, you first convert the U-value to its equivalent fraction and then invert it. For instance, the equivalent fraction of U-0.166 would be 166/1000 or 1/6. This inverts to 6/1 or 6, giving you an R-value of 6.
For most consumers, U-value is likely to be of concern only when shopping for new windows, where efficiency is frequently stated in terms of U-value rather than R-value.
Vapor barrier: a material designed to resist the migration of moisture through a wall or other building components. As water vapor in the air moves from a warmer to a cooler part of the building it can settle and condense on cooler building components, such as rafters, beams, and walls, eventually causing those components to mildew, rust or rot. Vapor barriers, which are impermeable to water vapor migration, help to protect against this possibility. The most common vapor barriers are made of plastic, but other materials, including oil paint, can also serve the purpose.
Watt: a unit of electric power. The amount of power required by electric appliances is expressed in watts.
Watt-hour: a unit of electric energy, equal to one watt used over a period of one hour.
Weatherstripping: a product designed to seal the cracks that exist between two moving parts or one moving and one stationary part of windows, doors and other movable building components. Weatherstripping is used to improve a building’s energy efficiency by preventing the unintentional entry of unconditioned outdoor air.
City Water, Light & Power (CWLP), Springfield, IL
Vifaa ambavyo jengo linatengenezwa, pamoja na mifumo na vifaa vilivyowekwa, vinaweza kuathiri sana kiasi cha nishati ambacho jengo litatumia katika maisha yake yote. Ili kuwasaidia wateja kulinganisha athari ya uwezekano wa moja kwa nyingine, viwango vya ufanisi vimeundwa kwa vipengele vingi vya ujenzi na mifumo ya nishati. Kuna aina mbalimbali za viwango vya nishati sasa vingi, ambayo inaweza kuwa na kuchanganyikiwa kwa watumiaji viwango hivi walikuwa na lengo la kusaidia. Tutajaribu hapa kumaliza kuchanganyikiwa kwa kuelezea kila moja ya mifumo ya viwango iliyoorodheshwa hapa chini kwa njia rahisi iwezekanavyo. Pia ni pamoja na Glossary ya Efficiency Terms. Vifaa ambavyo jengo linatengenezwa vinaweza kuwa na athari kubwa kwa ufanisi wa muundo. Vifaa vinavyowezesha joto nyingi kupita kupitia viungo hivyo hupunguza ufanisi wa jengo. Kinyume chake, vifaa ambavyo hupinga kiasi kikubwa cha uhamisho wa joto vinaweza kusaidia kuhakikisha ufanisi mkubwa. Kiwango ambacho sehemu ya jengo (kama vile dirisha au mfumo wa ukuta) huhamisha joto huitwa thamani yake ya U. Uwezo wa nyenzo ya mtu binafsi (kwa mfano, kioo, mbao, chuma) kukabiliana na uhamisho wa joto inaitwa R-thamani yake. Wakati wa kuelezea ufanisi wa kifaa au mfumo wa nishati, tunazungumza juu ya jinsi mfumo huo unavyopaswa kutumia nishati ili kufanya kiasi fulani cha kazi. Kadiri matumizi yake ya nishati kwa kitengo cha pato, ndivyo mfumo huo unavyofanya kazi kwa ufanisi mdogo. Kwa mfano, kifaa cha kupoza hewa kinachohitaji umeme wa Watt 750 ili kutoa baridi ya 6,000 Btu itakuwa na ufanisi mdogo kuliko moja ambayo inaweza kutoa kiasi sawa cha baridi kwa Watt 500 tu. Vipimo vya kawaida vinavyotumika kwa mifumo ya nishati ni EER na SEER kwa mifumo mingi ya baridi ya kati; COP kwa baadhi ya pampu za joto na chillers; HSPF kwa pampu za joto katika hali zao za joto; na AFUE kwa tanuru za gesi na boilers. Kwa maelezo zaidi ya ufafanuzi wa maneno ya ufanisi zilizotajwa hapo juu, chagua yoyote ya mada zilizoonyeshwa hapa chini. Glossary ya maneno ya ufanisi (AFU) - kiwango cha ufanisi wa matumizi ya mafuta ya kila mwaka, kiwango cha ufanisi ambacho kinapima ufanisi ambao tanuru na boilers za moto za gesi na mafuta mengine hutumia chanzo cha msingi cha mafuta kwa msimu mzima wa joto. Ni haina kuzingatia ufanisi ambao sehemu yoyote ya mfumo, kama vile tanuru fan motor, hutumia umeme. AFUE ni asilimia ya wastani ya Btu ya joto la joto linalotolewa na kila Btu ya gesi (au mafuta mengine ya mafuta) inayotumiwa na mfumo. Kwa mfano, tanuru ya gesi yenye AFU ya 80% itatoa 0.8 Btu ya joto kwa kila Btu ya gesi ya asili iliyowaka. Wakati kulinganisha ufanisi wa tanuru mbalimbali gesi, ni muhimu kuzingatia AFUE, si ufanisi steady-hali. Steady-hali inahusu ufanisi wa kitengo wakati mfumo ni mbio kuendelea, bila mzunguko juu na nje. Tangu baiskeli ni ya asili kwa ajili ya mfumo katika kipindi cha msimu wa joto, hali ya kudumu haina kutoa kipimo cha kweli cha mfumo wa ufanisi msimu. Kwa mfano, tanuri za gesi zenye taa za majaribio zina ufanisi wa hali ya kudumu ya 78% hadi 80%, lakini ufanisi wa msimu wa BUE ni karibu na 65%. Kwa kweli, tanuru zote za hewa za gesi zilizowekwa katika eneo hili kutoka miaka ya 1950 hadi mwanzoni mwa miaka ya 1980 zilikuwa na AFUEs ya karibu 65%. Sheria ya Marekani inahitaji kwamba tanuru za gesi zinazotengenezwa na kuuzwa nchini Marekani ziwe na kiwango cha chini cha AFU (Affected Ureadable Energy). Kwa ajili ya nyumba za kuhamisha, furnaces na vifaa vya chini ya 45,000 Btu vinaweza kuwa na kiwango cha chini cha AFUE. Vifaa vya moto vya gesi vinavyoweza kuingizwa kwenye soko vina kiwango cha juu cha uingizaji wa hewa cha 97% - uingizaji wa hewa ya nje isiyo na hali ya hewa katika jengo lililochomwa na kupunguzwa kwa njia ya mitambo. Uingizaji wa hewa unaweza kutokea kupitia ufunguo wowote katika muundo wa nyumba, ikiwa ni pamoja na seams ambapo kuta hukutana na kuta nyingine, madirisha au milango, au chemchemi; mashimo ambapo waya au mabomba hupenya kuta, sakafu au dari, na kati ya reli za mkutano za kufungia mara mbili au chini ya mlango na kizingiti cha mlango. Ni moja ya sababu kuu ya ongezeko na hasara ya joto isiyo ya lazima na usumbufu wa kibinafsi katika majengo. Btu (British thermal unit): kipimo cha nishati katika joto. Inahitaji Btu moja ya joto ili kupasha joto paundi moja ya maji kwa 1 ° Fahrenheit. Btu inaweza kutumika ama kufafanua air conditioner ya baridi uwezo (yaani, idadi ya Btu ya joto ambayo inaweza kuondolewa na mfumo) au tanuru ya joto uwezo (yaani, idadi ya Btu ya joto ambayo inaweza kusambazwa na mfumo). Caulk ni kitu kinachotumiwa kufungia sehemu za kupenya hewa kati ya vitu viwili visivyoweza kuhamishwa, kama vile mahali ambapo nyuso za ukuta wa nje au wa ndani hukutana na fremu za dirisha au mlango na kwenye pembe zilizofanyizwa na siding. Kwa sababu ya kuonekana kwa madoa ya taa, taa za fluorescent (CFL) ni moja ya taa za kawaida za taa za fluorescent, na kwa sababu ya kuonekana kwa madoa ya taa, ni moja ya taa za kawaida za taa za fluorescent. Wao kuingiza ndogo-mduara looped au swirled bomba ambayo ni kushikamana na screw-katika msingi. CFLs hutoa viwango vya mwanga vinavyoweza kulinganishwa na balbu za incandescent za 20-to-150-watt kwa nishati ya chini ya 70% hadi 75%. Pia, inaweza kudumu kwa muda mrefu zaidi kuliko balbu za incandescent. Uendeshaji: uhamisho wa joto kupitia vitu vyenye nguvu kama vile kioo, ukuta wa matope, matofali, na vifaa vingine vya ujenzi. Kadiri tofauti kati ya joto la ndani na nje ilivyo kubwa, ndivyo mwendo wa umeme unavyoongezeka na ndivyo jengo linavyoweza kupata au kupoteza. Convection: uhamisho wa joto kwa au kutoka uso imara kupitia gesi au kioevu sasa. Kwa upande mwingine, joto la joto la nyumba hutokana na hewa (gesi) ambayo husafirisha joto kutoka kwa mwili wako, fanicha, kuta za ndani na vitu vingine vya joto hadi madirisha, sakafu, dari, kuta za nje na nyuso zingine baridi. COP (coefficient ya utendaji): kipimo cha ufanisi wa pampu ya joto (katika hali ya joto) katika joto maalum nje <unk> kawaida 47 ° F. CO2 = 1 inaonyesha kwamba kwa kila kitengo cha nishati inayotumiwa, kiasi sawa cha nishati (kwa namna ya joto) hutolewa na mfumo. Pampu ya joto yenye COP3 itatoa nishati ya joto mara tatu ya nishati inayotumiwa katika umeme katika joto la nje la 47 ° F. COP pia ni wakati mwingine kutumika kupima moja joto baridi ufanisi wa chillers. Btu ya joto hutengenezwa katika 47 ° F. Kwa mfano, hebu tuchukulie pampu ya joto hutumia umeme wa watts 4000 kutengeneza joto la Btu ya 42,000 kwa saa (Btu kwa saa) wakati ni 47 ° F nje. Ili kuamua COP, kwanza unaweza kubadilisha 4000 watts ya matumizi ya umeme katika Btu ya saa kwa kuzidisha 4000 mara 3.13 (idadi ya Btu katika saa moja ya umeme). Kwa mfano, unaweza kugawanya matokeo ya 13,648 Btuh kwa pato la joto la 42,000 Btuh. Hii inaonyesha kwamba pampu yako ya joto ina COP ya 3.8. Hii inamaanisha kwamba kwa kila Btu ya umeme mfumo hutumia, itazalisha kidogo zaidi ya 3 Btu ya joto wakati joto la nje ni 47 ° F. formula ya pili ni mara nyingi kutumika kuamua chiller ufanisi. Kwa kutumia njia hii ya hesabu, unaweza div 3.516 kwa idadi ya kilowatts (kW) kwa tani kutumika na mfumo. Kwa mfano, chiller ambayo hutumia 0.8 kW kwa kila tani ya uwezo itakuwa na COP ya 4.4 (3.516 kugawanywa na 0.8). Kwa upande mwingine, COP ya chiller mpya, yenye ufanisi zaidi, inayotumia kidogo kama 0.5 kwa tani, itakuwa kubwa kuliko 7 kW (3.516 kugawanywa na 0.5). Daylighting: mbinu ya kutumia mwanga wa asili kutoka madirisha, skylights na kufungua nyingine kwa kuongeza au kuchukua nafasi ya jengo la mfumo wa taa bandia. Wakati kutumika vizuri, daylighting inaweza kupunguza kituo cha's gharama za taa. Hata hivyo, wakati kutumika vibaya, inaweza si tu kusababisha viwango vya mwanga yasiyofaa lakini pia inaweza kuongeza gharama za baridi ya jengo kwa kuanzisha viwango vya juu vya joto la jua ndani ya jengo. Mfumo wa taa: kifaa cha taa ambacho kimetengenezwa hasa kwa ajili ya matumizi na aina fulani ya taa (bulb). Kwa mfano, kuongezeka kwa umaarufu wa CFLs kumesababisha maendeleo ya idadi inayoongezeka ya vifaa - ikiwa ni pamoja na torchieres, taa za meza, ngoma za dari, na chupa za ndani - zilizowekwa peke yake kwa matumizi na fluorescent ndogo. EER (Uwezo wa ufanisi wa nishati) ni kipimo cha nishati inayohitajika na mfumo wa baridi wakati unajaribu kudumisha starehe ya ndani kwa joto maalum la nje, kawaida 95 ° F. EER ni jina la kawaida kwa ajili ya dirisha air conditioners na geothermal pampu ya joto. EER ni sawa na idadi ya Btu kwa saa ya baridi iliyotolewa kwa joto la nje lililoelezwa, kugawanywa na idadi ya watts kutumika kutoa kiwango hicho cha baridi. EER ni EER ya kiwango cha joto cha joto cha joto, ambayo inahusisha kiwango cha joto cha joto cha joto cha joto cha joto cha joto cha joto cha joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto la joto. Kwa mfano, kitengo cha umeme cha 1200W kinaweza kutengeneza kiwango sawa cha baridi na EER ya 10 na itakuwa na ufanisi zaidi wa nishati. Kutumia mfano huo huo, unaweza kuona jinsi ufanisi unaweza kuathiri mfumo wa uendeshaji wa uchumi. Kwanza, unahitaji kuamua jumla ya kiasi cha umeme - kipimo katika kilowatt-saa - kitengo itatumia juu ya kipindi cha muda. Kilowatt-saa ni kiwango cha umeme kinachotumiwa kwa saa moja. Hii ni kipimo ambacho bili zako za matumizi ya kila mwezi huhesabiwa.) Kwa kufanya hivyo, hebu tufikirie kwamba unaendesha kiyoyozi chako cha dirisha cha 8 EER - kuchora watts 1500 wakati wowote - kwa wastani wa masaa 12 kila siku wakati wa majira ya joto. Kwa kiwango hiki, itatumia 18,000 watt-saa, au 18 kilowatt-saa (kWh) kila siku, na kusababisha matumizi ya jumla ya 540 kWh katika kipindi cha mwezi wa siku 30. Kwa bei ya joto ya $ 6.34 kwa kWh, itakugharimu $ 34.24 kuendesha kiyoyozi cha dirisha kila mwezi. Kwa mfano, mfumo wa EER wa 1200-watt, unaotumia masaa ya kilowatt 14.4 kwa siku na 432 kWh kwa mwezi, unagharimu $ 27.39, akiba ya 20% juu ya mfano wa chini wa ufanisi. Ufanisi: kiwango ambacho hatua fulani au kiwango cha kazi inaweza kuzalishwa kwa ufanisi kwa matumizi ya chini ya juhudi au mafuta. Kwa mfano, taa inayotumia umeme wa watts 15 kutokeza mwangaza wa lumen 900 itafanya kazi kwa ufanisi mkubwa kuliko ile inayotumia umeme wa watts 60 kutokeza mwangaza wa lumen 900. HSPF (kupasha joto msimu utendaji sababu): kipimo cha wote-umeme hewa-kwa-hewa pampu ya joto's ufanisi (katika hali ya joto) juu ya msimu mzima. HSPF ni kuhesabiwa kwa kugawanya jumla ya idadi ya Btu ya joto zinazotolewa katika msimu mzima na jumla ya idadi ya watt-saa zinazohitajika kuendesha mfumo katika msimu. Btu ya joto zinazozalishwa wakati wa msimu wa joto, watt-saa ya umeme inayotumiwa wakati wa msimu wa joto, na pampu nyingi za joto zilizowekwa katika Springfield leo zina HSPFs katika safu ya 7.0 hadi 8.0, ikimaanisha wanafanya kazi na ufanisi wa msimu wa mahali popote kutoka 205% hadi 234%. Kwa mfano, kwa kugeuza HSPF kwa asilimia, unahitaji kugawanya HSPF kwa 3.144, idadi ya Btu katika saa moja ya umeme. Kwa kila Btu ya nishati inayotumiwa katika msimu mzima wa joto, mfumo huu utatoa joto kutoka kwa Btu 2.05 hadi Btu 2.34 Kwa mfano, furnace za umeme zina ufanisi wa 100% (kwa kila Btu ya umeme, hutoa joto la Btu moja) au furnace za gesi mpya, ambazo zina ufanisi wa karibu 80% hadi 97% (kwa kila Btu ya gesi, hutoa joto la 0.8 hadi 0.97 Btu). Wakati wa kulinganisha mifumo ya nishati ambayo hutumia vyanzo tofauti vya mafuta ya msingi na gharama tofauti kwa Btu, ni muhimu kuelewa kwamba ufanisi wa uendeshaji wa juu haufai kuwa sawa na uchumi bora wa uendeshaji. Ingawa pampu ya joto ya umeme inaweza kufanya kazi kwa ufanisi mkubwa kuliko tanuru ya gesi, sio lazima iwe ya kiuchumi zaidi kuendesha kwa sababu ya tofauti ya bei kati ya vyanzo viwili vya mafuta. Insulation: bidhaa ambayo inazuia conductive na convective joto uhamisho. Baadhi ya vifaa ni asili bora insulators kuliko wengine kwa sababu wao kuwa na zaidi "mwisho hewa" mifuko. Mifuko hiyo ya gesi inayokamatwa husaidia kupunguza mwendo wa joto. Hata hivyo, ikiwa imesindika ifaavyo, karibu bidhaa yoyote, kutia ndani kioo, pamba, karatasi, na plastiki, yaweza kutumiwa kutengeneza insulation. Internal Heat Gain: mkusanyiko wa joto zinazozalishwa na jengo la mifumo ya nishati na vifaa na wakazi. Kulingana na idadi ya wakazi na aina na idadi ya mifumo ya nishati kutumika wakati wa siku, ni kawaida kwa ajili ya joto ndani kupata akaunti kwa 20% ya jumla ya majira ya joto baridi mzigo wa nyumba. Kilowatt (kW) - 1000 watts Kilowatt-saa: 1000 watts kutumika kwa saa moja au mchanganyiko wowote wa nishati mara kwa wakati ambayo ni sawa na kiwango hicho cha matumizi ya umeme, kama vile 1 watt kutumika kwa masaa 1000, 10 watt kutumika kwa masaa 100 au 50 watt kutumika kwa masaa 20. Kwa mfano, taa ya 100 watt iliyowekwa kwa saa tano kila siku ingetumia kWh moja kila baada ya siku mbili. Kilowatt-saa ni kipimo cha msingi ambacho makampuni ya umeme ya Marekani hutegemea bili nyingi za wateja. Kwa mfano, wateja wa CWL-P na WFP wana malipo ya wastani ya $ 5.50 kwa kila kilowatt-saa ya umeme. Low-E: ni vifaa vya kupunguza kiasi cha joto radiant ambayo inaweza kuhamishwa kupitia kioo au nyingine translucent dirisha coverings. Low-E (ambayo inasimama kwa ajili ya chini-emissivity) mipako au filamu na uwezo wa re-radiate asilimia kubwa ya joto nyuma kuelekea chanzo chake. Katika majira ya joto, madirisha ya E-Low yanaweza kuwa na ufanisi katika kupunguza kiasi cha joto la jua ambalo linaweza kuingia ndani ya nyumba, na wakati wa baridi kali, zinaweza kupunguza kiasi cha joto linalotokana na tanuru ambayo inaweza kupotea nje. Lumen: kitengo cha mwanga inayotolewa na chanzo cha mwanga. Lumen ni kipimo kutumika kulinganisha ngazi ya mwangaza zinazotolewa na vyanzo tofauti vya mwanga. Kipindi cha malipo: kiasi cha muda inachukua kufikia faida kamili ya uwekezaji. Kwa mfano, ikiwa kifaa cha hali ya hewa cha ufanisi wa juu kinagharimu zaidi ya $ 300 kununua kuliko mfano wa ufanisi wa chini, lakini kinakuokoa $ 100 kwa mwaka katika gharama za uendeshaji, kipindi chako cha malipo ya uwekezaji wa $ 300 ya ziada itakuwa miaka mitatu. Radiation: njia ya uhamisho wa joto ambapo joto ni kupitishwa kutoka uso kwa uso kupitia mawimbi ya infrared. Joto la mnururisho huongeza joto la nyuso zinazoguswa bila kuongeza joto la hewa inayopita ndani yake. Miili yote yenye joto hutoa nishati ya infrared. Return on investment (ROI) ni kiwango cha kila mwaka ambacho uwekezaji unatoa mapato. Ni mahesabu kwa kugawanya mapato ya kila mwaka na uwekezaji. Kwa mfano, akaunti ya benki ya akiba inayolipa $ 3 kwa mwaka kwa uwekezaji wa $ 100 ina ROI ya 3% ($ 3 kwa $ 100). ROI ya uwekezaji wa ufanisi haikutoka kwa pesa zilizolipwa kwako, bali kwa pesa zilizopunguzwa na wewe kwenye bili zako za nishati. R-thamani: kipimo cha uwezo wa nyenzo ya kupinga uhamisho wa joto. Bidhaa insulation ni rated kulingana na R-thamani. Zaidi yake R-thamani, kubwa zaidi bidhaa uwezo wa kupinga mtiririko wa joto itakuwa. Vifaa fulani ni sugu zaidi kwa uhamisho wa joto kuliko vingine, na hivyo kuwapa maadili ya juu ya R. Moja ya njia bora ya kuongeza bidhaa ya R-thamani ni kuongeza kiasi cha gesi (ikiwa ni pamoja na hewa) ndani au moja kwa moja kuzunguka yake. Kwa mfano, kioo cha dirisha moja la kioo hakina thamani ya R, lakini filamu nyembamba ya hewa ambayo kwa kawaida ipo pande zote mbili za kioo hutoa dirisha R-thamani ya karibu 0.83. Kuongeza kioo cha pili na kufungia nafasi kati ya vioo itaongeza unene wa moja ya tabaka insulating gesi, hivyo zaidi ya mara mbili dirisha la R-thamani. Mfano mwingine wa jinsi uwepo wa nafasi za hewa wafu huathiri thamani ya R ya bidhaa inaweza kuonekana na mbao. Miti ya mwaloni, kama vile mwaloni, kwa kawaida huwa na thamani ya kutenganisha ya R-1 kwa inchi ya unene. Hata hivyo, mbao laini, kama vile msonobari, huenda zikawa na thamani ya R iliyo kubwa mara mbili kwa sababu ya idadi yao kubwa ya pores zilizojaa hewa. Bidhaa zilizotengenezwa hasa kwa kusudi la kuzuia uhamisho wa joto usiofaa huitwa insulation. Insulation inaweza kutengenezwa kwa vifaa mbalimbali, kutia ndani magazeti ya zamani na nyuzi za mbao, nyuzi za kioo, na povu za synthetic. Inaweza pia kuja katika aina mbalimbali ya miundo, ikiwa ni pamoja na blanketi laini, bodi ngumu, au fluffy granular loose-kutoa, lakini nini wote wana katika kawaida ni wingi wao wa pores hewa kujazwa au mifuko. R-thamani halisi ya bidhaa insulation inaweza kutofautiana sana, kulingana na muundo wao na fomu. Ni rahisi zaidi kwa ajili ya kuunganisha na kuunganisha, kama vile perlite, vermiculite, na R2-R2 kwa inchi ya unene, lakini kwa ajili ya kuunganisha, kama vile R2 kwa inchi ya unene, ni rahisi kwa ajili ya kuunganisha. Vitambaa vya fiberglass na cellulose loose-fill, mbili ya insulation ya kawaida ya makazi, zina R-thamani ya 3.1 hadi 3.7 kwa inchi. SEER (Saison Energy Efficiency Ratio) ni kipimo cha jinsi mfumo wa baridi ya kati unavyoweza kufanya kazi kwa ufanisi wa nishati kwa kipindi chote cha baridi. Neno hili ni mara nyingi kutumika kwa kituo cha hewa-kwa-hewa pampu ya joto (katika hali ya baridi) na air conditioners. SEER ni dividendi ya idadi ya Btu ya baridi zinazotolewa katika msimu, kugawanywa na jumla ya idadi ya watt-saa mfumo hutumia. Sheria ya Marekani inahitaji kila mfumo wa kugawanyika wa kati unaotengenezwa na kuuzwa nchini Marekani kuwa na kiwango cha chini cha SEERs ya 10. Kuanzia Januari 2015, kiwango cha chini cha mfumo wa utoaji wa huduma kwa watumiaji wa mtandao utaongezeka hadi 14. "Kupima kiwango cha joto cha kawaida kwa kila mwaka ni sawa na ""mwezi wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu) na ""mwaka wa joto la kawaida"" (Btu)." Settled wiani: kiasi (kuficha) ya insulation iliyobaki baada ya kuwa na nafasi ya kukaa. Neno hili ni mara nyingi kutumika kwa loose-jaza insulations - hasa wale alifanya ya cellulose. Ili kuhakikisha insulation ya cellulose ya kujaza huru itahifadhi thamani yake ya insulating (R-thamani) mara moja imeweka, utahitaji kuiweka kwa kina ambacho ni 20% hadi 25% kina zaidi kuliko kiwango chako cha R-thamani ya wingi. Joto la jua ni joto linalojengwa ndani ya jengo kutokana na mwangaza wa jua unaingia kupitia nyuso za uwazi au za uwazi, kama vile madirisha, na hubadilishwa kuwa joto baada ya kugonga nyuso zingine ndani ya jengo. Katika majira ya joto, jua inaweza kusababisha zaidi ya 50% ya joto la ndani la nyumba. Thermostat Setback: juhudi ya makusudi ya kudhibiti matumizi ya nishati ya jengo kwa kudhibiti manually au moja kwa moja thermostat mipangilio kulingana na kiasi cha baridi au joto ambayo inahitajika wakati wowote wa siku au usiku. U-thamani: kipimo cha jinsi urahisi joto inaweza mtiririko kupitia kioo, matofali, drywall na vifaa vingine vya ujenzi. U-thamani, ambayo ni kuonyeshwa katika decimals (kwa mfano, U-0.166), ni kinyume cha R-thamani. Kadiri thamani ya U ilivyo kubwa, ndivyo vifaa vya ujenzi vitakavyokuwa visivyo na ufanisi. Chini ya vifaa <unk>s U-thamani, juu yake R-thamani itakuwa. Kuamua R-thamani ya bidhaa ambayo U-thamani ni kupewa, wewe kwanza kubadilisha U-thamani kwa sehemu yake sawa na kisha invert yake. Kwa mfano, sehemu ya U-0.166 itakuwa 166 × 1000 au 1 × 6. Hii ni sawa na 6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x6x7x7x7x7x7x7x7x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x8x Kwa watumiaji wengi, U-thamani ni uwezekano wa kuwa na wasiwasi tu wakati wa ununuzi kwa ajili ya madirisha mapya, ambapo ufanisi ni mara nyingi alitaja katika suala la U-thamani badala ya R-thamani. Vapor barrier: nyenzo iliyoundwa ili kukabiliana na uhamiaji wa unyevu kupitia ukuta au vipengele vingine vya ujenzi. Mvuke wa maji unapoenda kutoka sehemu ya joto hadi sehemu ya baridi ya jengo, unaweza kuanguka na kuhifadhiwa kwenye sehemu za baridi za jengo, kama vile rafters, beams, na kuta, na hatimaye kusababisha sehemu hizo kuwa na kuvu, kutu au kuoza. Vizuizi vya mvuke, ambavyo haviwezi kupenya uhamiaji wa mvuke wa maji, husaidia kulinda dhidi ya uwezekano huu. Vizuizi vya mvuke vinavyotumiwa kwa kawaida hutengenezwa kwa plastiki, lakini vifaa vingine, kutia ndani rangi ya mafuta, vinaweza pia kutumiwa. Watt: kitengo cha nguvu ya umeme. Kiasi cha nishati inayohitajika na vifaa vya umeme huonyeshwa katika watts. Watt-saa: kitengo cha nishati ya umeme, sawa na watt moja kutumika juu ya kipindi cha saa moja. Weatherstriping: bidhaa iliyoundwa kwa ajili ya kufungia ufa kwamba zipo kati ya sehemu mbili kusonga au moja kusonga na moja sehemu ya kusimama ya madirisha, milango na vipengele vingine vya ujenzi kusonga. Weatherstripping hutumiwa kuboresha ufanisi wa nishati ya jengo kwa kuzuia kuingia bila kukusudia kwa hewa ya nje isiyo na hali ya hewa. Jiji la Maji, Mwanga na Nguvu (CWLP), Springfield, IL