Research on passive energy-saving design of college library building

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Research on passive energy-saving design of college library building

Qiu Ju, Ding Xinyu Jlju, Changchun, China

Abstract

College library is educational infrastructure, which takes up the heavy responsibilities of education, research and providing reading service for teachers and students. It is an important structure of college educational system as well as large consumer of resource and energy. Therefore, building energy-saving library is of great practical significance and far-reaching educational significance for building energy-saving college. This paper describes the advantages of passive energy saving design strategy such as low initial investment and operation, maintenance cost. Meanwhile, some excellent cases, which are from domestic and abroad and hope to reduce the energy consumption of the library in later use will be combine. To provide some meaningful reference for the construction of green ecological library.

Keywords: college library; passive energy-saving technology; energy-saving technologies; green buildings

Абстракт

Цю Цзюй, Дин Синьюй ЦУС, Чанчунь, Китай

ИССЛЕДОВАНИЕ ВОПРОСА ПАССИВНОГО ЭНЕРГОСБЕРЕЖЕНИЯ НА ПРИМЕРЕ УНИВЕРСИТЕТСКОЙ БИБЛИОТЕКИ

Ключевые слова: университетская библиотека, энергоэкономичная технология, технология энергосбережения, зеленые здания.

Introduction

passive energy saving green library

College library is a high-energy consuming department. Besides, almost all colleges are non-profitable. Therefore, the active energy-saving technology application cannot recover the initial investment within short term through saving energy costs which leads to the failure of applying active energy-saving technology into the construction of colleges and universities comprehensively and extensively. The passive energy-saving technology reduces energy consumption of buildings through intervention with non-mechanical and non-electric equipment. To be specific, it refers to achieving the goal of reducing buildings' energy consumption of heating, air-conditioning and ventilation, etc. through laying out building orientation reasonably, designing sun-shade, building palisade structure heat preservation and heat insulation and using natural ventilation during the architectural planning and designing. The application of passive energy saving technology doesn't increase large costs of early investment, operation and maintenance. Thus, it is more suitable for library construction, bringing the attention of current colleges. This paper will study several passive energy-saving design strategies, which can be applied extensively in college library construction.

1. Natural daylighting strategy

Compared to artificial lighting, natural lighting not only saves energy, but also provides more comfortable light, more suitable for the needs of human eyes to read. Thus, the library building indoor natural lighting requirements are higher. The method of enhancing the natural lighting of buildings usually is to reduce the daylighting depth or strengthen natural light transmission characteristics of the envelope. Such as the Shandong Transportation College (Changqing Campus) Library (fig. 1) reduces the building's lighting depth by setting up step-like retreat-style structure which cut-through the atrium and the west side of the building combining with landscape condition in the building area; at the same time, it introduces more natural light through designing the larger window-wall ratio and high transmittance skylights. [1, p. 66].

Figure 1. West side of the lake back desktop effect

Figure 2. Shanghai Maritime University Library, the first floor

Figure 3. Los Angeles City College Library lateral lighting

Natural lighting of the inner space of building is mainly through lighting from the top and lateral reflection. The top natural daylighting strategy is widely adopted in the library building of colleges and universities. Such as the Shanghai Maritime University Library, the first floor of the hall and the top multi-purpose reading room all use the top daylighting strategy (fig. 2), solving the problem successfully that uneven indoor natural lighting because of large depth. Although top natural lighting can provide high-quality natural light for building, it consumes a certain amount of air-conditioning energy accordingly, so the top natural daylighting often matches with the automatic shading system, or uses a small area of Low-E glass, or uses tooth-like structure on the roof to avoid large area direct sunlight into the room [2, p. 17]. Therefore, with reasonable and effective technical measures, the top of the natural lighting will be a very effective passive energysaving design.

As for lateral reflecting natural lighting design method, in the past campus building, although it has been used inadvertently, but has not been well found its lighting function. Most of them are simply used as a shade measures. The effect of lateral reflecting natural light The natural lighting effect is related to the width of the reflector. Such as the United States Los Angeles City College Library, University of California, Los Angeles, University of Las Vegas and other university buildings all adopt this way to improve the natural lighting effect of buildings, so as to meet energy saving requirements (fig. 3).

2. Natural ventilation strategy

To achieve a better natural ventilation effect, the building layout should follow the dominant wind direction in summer. The Shanghai Maritime University library is oriented towards the southeast which is consistent with the dominant summer wind in Shanghai.

The systems of airflow inside the building can be divided into two ways, horizontal pulling-through and vertical top-down. In library buildings, windows usually are designed in the reading room, interior corridor or outside the corridor to facilitate the formation of the air flow through the building horizontally. The arrangement of the atrium in the library is the most common design method. The atrium facilitates the formation of the air flow vertically. The hot air drawing effect of wind chimneys on the atrium can strengthen the natural ventilation and reduce the time of using air conditioner.

The adjustable ventilation louvers can be used in the building. For example, the ventilation louvers (fig. 4) are used in the south and north windows of the Shandong Transportation College Library to adjust the wind speed of entering the room. That's because firstly, during the summer, the indoor ventilation needs to be strengthened to reduce the indoor temperature and humidity and increase indoor thermal comfort, which requires increased window area; secondly, in winter, the window area is too large will result in Increasing heat dissipation outside the window and decreasing the indoor temperature which need to reduce the window area; thirdly, in the transitional season when the window shut down we need to adjust the wind speed through louver for indoor ventilation at the same time without reducing the quality of thermal environment nearby the window.

Figure 4. Ventilation louvers on the outside of the building

Natural ventilation is a very effective passive energy-saving measure. It should be widely used in college building design to save air conditioning energy consumption greatly under non-extreme temperature environment.

3. Outside shading strategy

Shading in hot summer is particularly important. Different shading ways should be selected according to the direction of the hole on the envelope structure. The effect of outside shading is better than the inner shading. Some new sunshine adjustment systems such as controllable shading also can be used. Shade and insulation have a certain impact on ventilation. Thus, the structure of the shade should be considered coordinately. For example, the use of slot-type sun visor is a good way. Facade shading design is not only structural design but also can use the corridors and other building components and vertical greening integrated treatment so that the vertical shade design and facade morphology treatment can combine organically [3, p. 30]. The exterior shading strategies include horizontal shading, vertical shading, horizontal and vertical shading, external shade curtains, shading between buildings and buildings.

Shandong Communication College Library uses horizontal shading strategy, the southern window of the library using horizontal shading (fig. 5). Horizontal shading can effectively block the sunlight from larger high angle and the transmission sunlight from the top. So it is suitable for the part which is close to the south. Jinan area in the summer need to block the hot sunshine, but in most seasons need to fully absorb the sun's heat, in order to block the summer hot sunshine while not block the warm of the outer horizontal visor.

Figure 5. Sunlight between the south side

Sunshine not block the warm sunshine in winter, the appropriate distance should be determined through the difference of winter and summer sun.

Note that in determining the overhang length of horizontal visor, you should calculate based on the sunshine condition of winter solstice and summer solstice these two typical solar terms. The minimum overhang length should be able to block the sunshine of noon of summer solstice. The maximum overhang length should not affect the sunshine of noon of winter solstice to enter the room. Ordinary window on the south side of the library in the window under the 450mm out of 500mm wide louver shade-type shade, leaves can fine-tune the angle, not only to prevent the summer noon strong sunlight into the room, but also will not affect the introduction of solar energy in winter. Sunshade shading method is to place the window curtains. This method is widely used in the Nordic, sunshade can rise and fall automatically according to the requirements, has a good shade effect, while not affecting the use of internal space. There are practices to metal blinds on the middle of double insulating glass, through the manual opening and closing blinds for shading, but this practice has been proved that it cannot meet the insulation requirements, because the metal louvers under the sunlight will heat, double insulating glass cannot be effective within the heat, its own become a heat source radiating heat into the room. This method should not be used as a shade measures.

Building and building mutual shade can be used for climate hot and wind weak areas. Such as the Middle East building, the windows need to be blocked and the wall needs to be blocked as well to reduce energy consumption. So their buildings very close to other buildings. The mutual block is a very effective energy-saving method and at the same time can save construction land.

4. Building green energy-saving strategy

Nature provides us with some natural shade means, trees or climbing plants can block the sun to form shadows and lower wall surface temperature. Plant shading for blocking solar radiation, reducing the indoor thermal environment plays a decisive role. The green shade is different from building components shade, because of its heat flow. Plants convert solar energy into bioenergy through photosynthesis, the temperature of the plant leaves itself is not significantly increased, while the temperature of the sunshade components will be significantly increased, part of the heat will also be transmitted to the room through a variety of ways. Therefore, the green energy-saving strategy gradually rises.

Building green energy-saving strategies include atrium greening, retreat greening, roof greening.

Atrium greening means we can place potted plants or plant surface plants directly at library atrium to introduce green plants into library. It can play the effect of air cushion and beautifying the environment during controlling the indoor environment. Lush plant communities can strengthen the contact between man and nature, increase the green looking ratio of people, regulate air humidity and clean indoor air which is conducive to human health.

The retreat greening can enrich building image and improve local microclimate of the library. For example, the library (fig.l) of Shandong Jiaotong University (Changqing Campus) in order to solve the problem of heat radiation and glare caused by the library drying in the library west side, they set up wood shade at the outdoor stack Layer back on the platform and plant deciduous climbing plants to form the west green shade barrier, can improve the local micro-climate. In summer, it can block the direct sunlight and maintain the indoor temperature and visual comfort; in winter, the plants without leaves do not block the sunshine.

Roof greening (fig.6) can significantly increase the thermal insulation effect of the roof construction.

The working principle of roofing works is to plant plants on the rigid concrete roof. Planting medium and plants can absorb and block the sunlight so that to achieve the goal of cooling insulation.

Regardless of the outside temperature, through the protection of the roof, the indoor thermal environment can be improved significantly. This is mainly because the grass and leaves grow and cover on the roof can block most of the solar radiation heat while moist soil can make the temperature stable.

Figure 6. Schematic diagram of roof

The formation of biological climate buffers zone. Roof garden maintain adequate water and soil can form biological climate buffer zone between artificial architecture and nature, provide a good microclimate environment for building system, improve the biological diversity of building system and achieve harmony between human and the nature.

Conclusion. In the energy-saving design of buildings, the passive method and the active method are closely related and complementary. But the architect should grasp an important design concept, "energy-saving" firstly.

Then, they try their best to design buildings with good environment quality with passive energy-saving technology but without using equipment as far as possible. Only when the environment is the worst and the passive method cannot meet the requirements of the building, can the equipment engineer assist and supplement the active design.

Of course, the equipment engineer also can give reference to architect about passive energy-saving design, in order to better coordinate. The using of a variety of passive energy-saving design strategy makes the college library buildings become greener under the condition that do not increase the initial investment and the cost of operation and maintenance. This is not only the desire of every designer, but also the common aspiration of general public aspiration.

References

1. Honggang Li. Xiaorui Zhou. Passive Ecological Design Practice for Library Building.Shandong; China, Practical Exploration, -- 2011(02). -- 66p.

2. Gang Chen. Discussion on The Design Strategy of The Passive Energy Saving Applied to Universities Buildings; China, Urban Architecture, -- 2013(02). -- 17p.

3. Huajin Chen, Baofeng Li, Zhifeng Dong. Review of Passive Building Energy Conservation Design; Shenyang, Building Energy Conservation, -- 2007(03). -- 30p.

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