Demonstration of energy savings of cool roofs

Konopacki, S.; Gartland, Lisa Mummery; Akbari, Hashem; Rainer, Leo

doi:10.2172/296885

Cited by 58 publications

(36 citation statements)

References 1 publication

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“…For example, use of a reflective coating on the roof of buildings in sunny, hot climates can save on air conditioning costs inside. Two medical offices in Northern California used reflective roofs on their buildings and found summertime daily air-conditioning savings of 13 and 18% and reduced demand of 8 and 12% (Konopacki et al, 1998). For colder climates, heat lost due to cool roofs (in the winter, for example) also needs to be taken into account, and often negates savings.…”

Section: Solar Heating (Solarwall)mentioning

confidence: 99%

Energy Efficiency Improvement and Cost Saving Opportunities for the Vehicle Assembly Industry: An ENERGY STAR Guide for Energy and Plant Managers

Galitsky¹

2008

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The motor vehicle industry in the U.S. spends about $3.6 billion on energy annually. In this report, we focus on auto assembly plants. In the U.S., over 70 assembly plants currently produce 13 million cars and trucks each year. In assembly plants, energy expenditures is a relatively small cost factor in the total production process. Still, as manufacturers face an increasingly competitive environment, energy efficiency improvements can provide a means to reduce costs without negatively affecting the yield or the quality of the product. In addition, reducing energy costs reduces the unpredictability associated with variable energy prices in today's marketplace, which could negatively affect predictable earnings, an important element for publicly-traded companies such as those in the motor vehicle industry.In this report, we first present a summary of the motor vehicle assembly process and energy use. This is followed by a discussion of energy efficiency opportunities available for assembly plants. Where available, we provide specific primary energy savings for each energy efficiency measure based on case studies, as well as references to technical literature. If available, we have listed costs and typical payback periods. We include experiences of assembly plants worldwide with energy efficiency measures reviewed in the report. Our findings suggest that although most motor vehicle companies in the U.S. have energy management teams or programs, there are still opportunities available at individual plants to reduce energy consumption cost effectively. Further research on the economics of the measures for individual assembly plants, as part of an energy management program, is needed to assess the potential impact of selected technologies at these plants.iv

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Section: Solar Heating (Solarwall)mentioning

confidence: 99%

Energy Efficiency Improvement and Cost Saving Opportunities for the Vehicle Assembly Industry: An ENERGY STAR Guide for Energy and Plant Managers

Galitsky¹

2008

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“…Akbari and Rainer (2000) measured daily a/c energy savings of 33Wh/m 2 (3.1Wh/ft 2 ) (1%) in two Nevada telecommunication regeneration buildings. Konopacki et al (1998) Akbari et al (1997a) have shown from an increase in roof reflectance in one monitored Sacramento house daily summertime cooling-energy savings of 14Wh/m 2 (1.3Wh/ft 2 ) (63%) and peak-power reduction of 3.6W/m 2 (0.33W/ft 2 ) (25%), and in a Sacramento school bungalow, cooling-energy savings of 47Wh/m 2 (4.4Wh/ft 2 ) (46%) and peak-power reduction of 6.8W/m 2 (0.63W/ft 2 ) (20%). In an office, museum and hospice with reflective roofs in Sacramento, Hildebrandt et al (1998) measured daily a/c savings of 10 Wh/m 2 (0.9 Wh/ft 2 ), 20 Wh/m 2 (1.9 Wh/ft 2 ) and 11Wh/m 2 (1.0Wh/ft 2 ) (17%, 26% and 39%) .…”

Section: Literature Reviewmentioning

confidence: 99%

“…A "generic gray" asphalt shingle has a laboratory tested initial albedo of 0.22, and the albedo of a green or brown shingle is about 0.12-0.15 (CRMD, 2001). The roofs-built-up asphalt capsheet with light-gray granules-of three commercial buildings in California were coated with a whiteelastomeric material, where the measured pre-coated albedo ranged from 0.16 to 0.24, the initial post-coated albedo was 0.6, the unwashed albedo ranged from 0.47 to 0.56, and the washed albedo was 0.59 (Konopacki and Akbari, 1998b).…”

Section: Solar-reflective Roofsmentioning

confidence: 99%

Energy impacts of heat island reduction strategies in the Greater Toronto Area, Canada

Konopacki¹,

Akbari²

2001

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In 2000, the Toronto Atmospheric Fund (TAF) embarked on an initiative to quantify the potential benefits of Heat Island Reduction (HIR) strategies (shade trees, reflective roofs and pavements) in reducing cooling energy use in buildings, lowering the ambient air temperature and improve air quality. This report summarizes the efforts of Lawrence Berkeley National Laboratory (LBNL) to assess the impacts of HIR measures on building cooling-and heating-energy use. We discuss our efforts to calculate annual energy savings and peak-power avoidance of HIR strategies in the building sector of the Greater Toronto Area. The analysis is focused on three major building types that offer most saving potentials: residence, office and retail store. Using an hourly building energy simulation model, we quantify the energy saving potentials of (1) Results show potential annual energy savings of over $11M (with uniform residential and commercial electricity and gas prices of $0.084/kWh and $5.54/GJ) could be realized by ratepayers from the combined direct and indirect effects of HIR strategies. Of that total, about 88% was from the direct impact roughly divided equally among reflective roofs, shade trees and windshielding, and the remainder (12%) from the indirect impact of the cooler ambient air temperature. The residential sector accounts for over half (59%) of the total, offices 13% and retail stores 28%. Savings from cool roofs were about 20%, shade trees 30%, wind shielding of tree 37%, and indirect effect 12%. These results are highly sensitive to the price of gas. Assuming a residential gas price of $10.84/GJ (gas price during December 2001), the net annual savings are reduced to about $10M; about 78% resulted from wind-shielding, 16% from shading by trees, and 5% from cool roofs. Potential annual electricity savings were estimated at about 150GWh or over $12M, of that about 75% accrued from roofs and shade trees and only 2% from wind shielding. The indirect effect was 23%. Potential peak-power avoidance was estimated at 250MW with about 74% attributed to the direct impacts (roofs about 24%, shade trees 51% and wind-shielding a small negative %) and the remainder (26%) to the indirect impact. The greatest part of avoided peak power (about 83%) was because of the effects of the residences and the rest shared by offices (7%) and retail stores (9%). Executive SummaryIn 2000, the Toronto Atmospheric Fund (TAF) embarked on an initiative to quantify the potential benefits of Heat Island Reduction (HIR) strategies (i.e. shade trees, reflective roofs, reflective pavements and urban reforestation) to reduce cooling energy use in buildings, lower the ambient air temperature and improve air quality. This report summarizes the efforts of Lawrence Berkeley National Laboratory (LBNL) to assess the impacts of HIR measures on building coolingand heating-energy use. A companion report will address the air quality aspect (Taha et al., 2002). Background During the summer, solar-reflective roofs (also known as "high-albedo § " or "coo...

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“…Akbari et al (1997a) has shown in one monitored Sacramento house seasonal cooling energy savings of 63% and peak power savings of 25Y0, and in two identical Sacramento school bungalows cooling energy savings of 46~0 and peak power savings of 20% from an increased roof albedo. A recent project was completed that monitored the energy-saving impact of highreflective roofs in three California commercial buildings (Konopacki et al 1998c) and eleven Florida residences (Parker et al 1998). The commercial buildings saved up to 18~0 in seasonal electricity use and the residences saved an average of 19%.…”

Section: Previous Studiesmentioning

confidence: 99%

Demonstration of energy savings of cool roofs

Cited by 58 publications

References 1 publication

Energy Efficiency Improvement and Cost Saving Opportunities for the Vehicle Assembly Industry: An ENERGY STAR Guide for Energy and Plant Managers

Energy Efficiency Improvement and Cost Saving Opportunities for the Vehicle Assembly Industry: An ENERGY STAR Guide for Energy and Plant Managers

Energy impacts of heat island reduction strategies in the Greater Toronto Area, Canada

Energy Savings Calculations for Heat Island Reduction Strategies in Baton Rouge, Sacramento and Salt Lake City

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