Angular selective window systems: Assessment of technical potential for energy savings

Fernandes, Luís; Lee, Eleanor S.; McNeil, Andrew; Jonsson, Jacob C.; Nouidui, Thierry Stephane; Pang, Xiufeng; Hoffmann, Sabine

doi:10.1016/j.enbuild.2014.10.010

Cited by 38 publications

(14 citation statements)

References 13 publications

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“…To address these issues, several technologies have been developed, including internal and external blinds, transparent thermal barriers, angular selective shading systems, coatings, films, and multipane windows . The development of transparent wood as an alternative transparent material has aroused wide attentions .…”

Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

146

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The energy used for regulating building temperatures accounts for 14% of the primary energy consumed in the U.S. One-quarter of this energy is leaked through inefficient glass windows in cold weather. The development of transparent composites could potentially provide affordable window materials with enhanced energy efficiency. Transparent wood as a promising material has presented desirable performances in thermal and light management. In this work, the performance of transparent wood is optimized toward an energy efficient window material that possesses the following attributes: 1) high optical transmittance (≈91%), comparable to that of glass; 2) high clarity with low haze (≈15%); 3) high toughness (3.03 MJ m −3 ) that is 3 orders of magnitude higher than standard glass (0.003 MJ m −3 ); 4) low thermal conductivity (0.19 W m −1 K −1 ) that is more than 5 times lower than that of glass. Additionally, the transparent wood is a sustainable material, with low carbon emissions and scaling capabilities due to its compatibility with industryadopted rotary cutting methods. The scalable, high clarity, transparent wood demonstrated in current work can potentially be employed as energy efficient and sustainable windows for significant environmental and economic benefits.

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Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

146

View full text Add to dashboard Cite

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“…Simulations of angular-selective systems [19] have shown the importance of daylight use for the total energy use of a building. According to the US Energy Information Administration, electric lighting energy accounts for 20 % of the site energy use in commercial buildings, and for 38 % of the electric energy [20].…”

Section: Glare Control With Energy Management Systemmentioning

confidence: 99%

Potential energy savings with exterior shades in large office buildings and the impact of discomfort glare

Hoffmann

Lee

2015

Self Cite

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Exterior shades are highly efficient for reducing solar load in commercial buildings. Their impact on net energy use depends on the annual energy balance of heating, cooling, fan and lighting energy. This paper discusses the overall energy use intensity of various external shading systems for a prototypical large office building split into the different types of energy use and for different orientations and window sizes. Lighting energy was calculated for a constant lighting power as well as for dimmed lighting fixtures (daylighting control).In Section 3, slat angles and solar cut-off angles were varied for fixed exterior slat shading systems. While the most light-blocking shades performed best for the case without daylighting controls, the optimum cut-off angle with daylighting controls was found to be 30 deg for the office building prototype used in Chicago and Houston. For large window-to-wall (WWR) ratios, window related annual energy use could be reduced by at least 70 % without daylighting control and by a minimum of 86 % with daylighting control in average over all orientations.The occurrence of discomfort glare was is considered in Section 4 of the paper, which looks at the performance of commercially available exterior shading systems when an interior shade is used in addition to the exterior shade during hours when occupants would experience discomfort glare. Glare control impacts overall energy use intensity significantly for exterior shades with high transmittance, especially when daylighting controls are used. In these cases, exterior shades are only beneficial for window-to-wall areas ≥ 45% in the hot Houston climate. For smaller windows and in a heating/cooling climate like Chicago, exterior shades can increase energy consumption.

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“…Passive solar control measures include the use anti-reflective (low-emissivity) coatings 102 and angular selective window systems that differentially reflect the sunlight depending on the incidence angle. 103,104 The traditional and most straightforward way to actively control solar gains is by external blinds and this is by far for the most implemented solution. However, external blinds are prone to wind or hail damage and their installation and maintenance cost can be substantial.…”

Section: Solar Gains and Solar Control (G-value)mentioning

confidence: 99%

Energy in buildings—Policy, materials and solutions

Koebel

Wernery

Malfait

2017

MRS Energy & Sustainability

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Buildings account for ∼40% of global energy demands, and the increased adoption of innovative solutions for buildings represents an enormous potential to reduce energy demands and greenhouse gas emissions. Here, we critically review the current and future materials and solutions for the construction sector. We describe how policy affects innovative businesses and the adoption of new products and solutions. We investigate how the building envelope and user behavior determine building energy demands. Compared to conventional solutions, superinsulation materials (vacuum insulation panels, silica aerogel) can achieve the same thermal performance with drastically thinner insulation. With low-emissivity coatings and appropriate filler gasses, double and triple glazing reduces thermal losses by an order of magnitude. Vacuum and aerogel glazing reduce these even further. Switchable glazing solutions maximize solar gains during wintertime and minimize illumination demands whilst avoiding overheating in summer. Upon integration of renewable energy systems, buildings become both producers and consumers of energy. Combined with the dynamic user behavior, temporal variations in energy production require thermal and electrical storage and the integration of buildings into smart grids and energy district networks. The combination of these measures can reduce the energy consumption of the building's stock by a factor of three.

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Angular selective window systems: Assessment of technical potential for energy savings

Cited by 38 publications

References 13 publications

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Potential energy savings with exterior shades in large office buildings and the impact of discomfort glare

Energy in buildings—Policy, materials and solutions

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