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隨著新發明的紛紛出現，有很多方法是透過提高效率來取得能源。以下描述一些最常見、最有效的方法。
住宅
▲照明：在照明節能方面已取得很大的進步。傳統的白熾燈將90%的能量用來產生發光所需的熱量，這跟螢光燈泡相比，螢光燈泡的節能率是白熾燈的4倍，使用時間比白熾燈長9~13倍。在日本，80%的家庭使用螢光燈泡照明。利用透過窗戶的自然光照明也是一種有效的照明節能方法（對消費者來說，也節省開支）。據洛磯山脈學會（Rocky Mountain Institute）報告，在夏日陽光的直射下，透過一個1和寬1米、長1.6米的窗戶進入房間的光，比100個60瓦燈泡所產生的光度還多。
▲家用電器：在過去30年裏，很多已開發國家因為相關電器的技術進步而大幅降低了能源使用量。平均來說，爐子、熱水器、爐灶等家用電器已經減少了50%的用電量。冰箱、電熱水器和爐灶等電器有望將節能率提高到原來的3~6倍（在晴朗的天氣狀況下，太陽能熱水器能更有效的減少家庭的能源使用）。當置換舊家電時，最好先考慮節能效果最佳的產品，例如空調機就是家中用電量最大的電器，其後就是冰箱。
▲建築物：要使房屋和公寓建築在使用能源上更有效率，可以加厚牆壁、屋頂的隔熱層，利用窗戶來提高能源使用效率，在氣候炎熱的地方，在建築物附近種些樹，以上這些方法均可以保溫或維持涼爽。窗戶讓光和熱得以入室內，但是在冬天，這是窗戶也是屋內損失熱量的主因，在夏天，這又是獲得熱量的主要來源。然而，根據某些估計資料，現代的高能率窗戶會幫助將家庭室內加熱、保持冷度和照明的成本降到最低，減少了35~45%。影響窗戶能率的因素是光滑材料的種類（例如，玻璃、塑膠、處理過的玻璃等等）；玻璃的層數；每層間的空間大小；框架材料的熱導力，以及安裝的「緊密程度」。
樹蔭能在光熱達到建築之前，就減少這種因吸收了陽光的熱能而得到的光熱，它還能經由水分蒸發冷卻周圍的空氣。整個夏季裡，空調系統的節能量約25~60%，其中差異取決於建築物類型、隔熱率、景觀設計以及氣候。有些處於炎熱氣候中的電力公司會贊助植樹專案。美國加州的沙加緬渡社區電力公司（SMUD）正在進行一項美國極具野心的植樹專案。沙加緬渡社區電力公司計劃在2000年之前，透過它的「樹蔭專案」種下50萬棵樹，到1995年為止，這家公司已經種植16萬多株樹木，大多都種在該市住宅區。這加電力公司為此專案提供資金，由非營利性的沙加緬渡植樹基金會執行計畫。生長快速的落葉型樹木很不錯，因為冬天裏陽光能穿過這些樹。
商業、機關組織、工業
▲技術和用途：在工業環境下提高效率總是包括改善基本的生產技術--尤其是汽車業。根據斯德哥爾摩環境學會說，很多國家的汽車業最多能占工業用電總量的三分之二。由關製造節能型汽車的科學非常複雜，往往是有其特殊具體的工業用途。在很多國家，煉鋼業的能源使用量也相當大，而技術先進的熔爐可節省40~50%的能源。同樣，據估計透過使用改進的設備，鋁的生產效率能提高50%，使用回收鋁還能提高更多效率（第二次使用鋁只需首次生產鋁所需能量的4%）。對某些行業來說--如超市、餐廳及醫院--冷藏設備有相當大的節能潛力。
▲建築物：雖然住宅型和商用建築的能元使用效率的方式有些共同之處，令商用建築提高效率的最佳方法是改進空調系統和照明系統。
版權歸屬 國際河網IRN，環境資訊協會 (金霞、陶俊譯，李傑、李瑞玉 審校)
中英對照全文：http://e-info.org.tw/issue/water/2001/issue-water-irn01080601.htm
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There are many, many ways to capture energy through efficiency improvements, with new innovations coming out all the time. The following describes some of the most common and best efficiency measures.
Residential
▲Lighting: Great progress has been made in making lighting more energy efficient. Traditional incandescent light bulbs use 90 percent of their energy to produce enough heat to glow, compared to compact fluorescent light bulbs, which are four times more efficient and last 9-13 times longer. In Japan, 80 percent of homes are lit by compact fluorescent bulbs. Making use of natural daylight through windows is also an effective way to save energy (and costs to the consumer) from lighting. According to the Rocky Mountain Institute, a 1x1.6 metre window in direct summer sun lets in more light than a hundred 60-watt light bulbs.
▲Home appliances: Over the past three decades many developed countries have greatly reduced their energy consumption because of improvements to appliances. Household appliances such as furnaces, water heaters and cooking ranges have cut their electricity use by an average of 50 percent. Appliances such as refrigerators, electric water heaters and stoves have the potential of becoming 3-6 times more efficient (and in sunny climates, solar water heaters can reduce a home's energy use even further). When older appliances are being replaced, it is good to prioritize to get the most energy savings: air conditioners are the single biggest energy user in a home, followed by refrigerators.
▲Buildings: Houses and apartment buildings can be made more efficient (for both heating and cooling) by increasing insulation levels in the walls and roof, improving the energy-efficiency of the windows and, for hot climates, planting shade trees near the building. Windows bring light and warmth into buildings, but can also be major sources of heat loss in the winter and heat gain in the summer. However, modem energy-efficient windows can help minimize a home's heating, cooling, and lighting costs by 35-45 percent, according to some estimates. The factors which affect the energy efficiency of a window are the type of glazing material (e.g., glass, plastic, treated glass); the number of layers of glass; the size of the air space between the layers; the heat conductance of the frame materials, and the "tightness" of the installation.
Shade trees reduce solar heat gain by absorbing heat from the sun before it can reach the building, as well as cooling the surrounding air through
evapotranspiration. Air conditioning savings from landscaping range from 25-60% over the course of the summer, depending on building type, amount of insulation, landscape design and climate. Some utilities in hot climates have sponsored tree-planting programs. For example, The Sacramento Municipal Utility District
(SMUD) in California is operating one of the US's most ambitious tree planting program. SMUD plans to plant 500,000 trees by the year 2000 through its Shade Tree Program, and had planted more than 160,000 trees by 1995, mostly in residential areas of the city. The utility funds the program, which is implemented by the nonprofit Sacramento Tree Foundation. Fast-growing deciduous trees are a good choice, as they allow sun in winter.
Commercial, Institutional and Industrial
▲Technologies and
Appliances: Improving efficiency in industrial settings almost always includes improved basic production technologies - especially motors, which use up to two-thirds of industrial electricity in most countries, according to the Stockholm Environment Institute. The science of energy efficient motors is complex, and often specific to the industry application. In the steel industry, which uses a considerable share of energy in many countries, advanced technology furnaces can result in 40-45 percent energy savings. Similarly, it has been estimated that aluminum production can be 50 percent more efficient through the use of improved equipment, and even further through the use of aluminum recycling (secondary use of aluminum requires just 4 percent of the energy needed to produce it the first time). For some industries - such as supermarkets, restaurants and hospitals - refrigeration is an area where big savings can be found.
▲Buildings: Although there are some similarities in efficiency measures for residential and commercial buildings, the best ways to make commercial buildings more efficient are through improvements to air conditioning and lighting systems.
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