Application of the Direct-Gain Passive Solar House on Middle and Small-Sized Public Building. Guifang Yang Ya Guo Ling Wang

Transcription

1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Application of the Direct-Gain Passive Solar House on Middle and Small-Sized Public Building Guifang Yang Ya Guo Ling Wang Northeast Petroleum University, Qinhuangdao The College of Architecture and Civil Engineering, Beijing University of Technology Keywords: The direct-gain passive solar house; Public building; Energy conservation Abstract. This paper starts from research in characteristics of the direct-gain passive solar house and presents the practical significance for the application of the house in small and midsize public building. The concrete methods are illustrated from location selection, external form, internal room arrangement, ventilation and maintenance structure and so on, which clarify the application way of the direct-gain passive solar house in the building. The purpose of this research is to reduce the energy consumption of the building itself and achieve building energy conservation. Introduction In today s society, the non-renewable resources are becoming fewer and will certainly be exhausted at all in some day. Therefore, countries around the world start to consider how to use renewable resources. In the construction industry, the solar energy, a new energy which has many advantages, is becoming increasingly popular with architects. Solar energy is a clean disposable and renewable resource. Our country is rich in solar energy resource, and the annual sunshine hours exceed 2000 hours in more than two-third of national area. In Tibet, Qinghai, Xinjiang, Gansu, Ningxia and Inner Mongolia plateau, the solar global radiation and sunshine time are the highest in our country, and the regions are also rich in solar energy resource around the world; Southern, eastern and the northeast of China are areas where have medium lighting resources. Good sunshine condition lays a solid foundation for China s application of solar technology in architecture [1]. This paper regards the small and midsize public buildings as the research object and presents a specific application method of the direct-gain passive solar house in them, which is the architectural form using solar energy directly. The Features of the Direct-Gain Passive Solar House According to the transformation of energy, the application types of solar energy can be divided into solar thermal conversion, photovoltaic and photochemical conversion. The use type of solar energy includes passive and active use. The passive use denotes that collecting solar energy, storing and releasing heat are all completed by building component itself, and pipe, water pumps and other mechanical equipment are not needed at all. The active solar use system means that collector and radiator are installed in the house, which are connected into heating and hot water system by pipelines, and the systems are forced circulations or can convey heat by water pumps or fans [2]. According to the current international standard name, the solar houses are divided into active solar house and passive solar house. The types of passive solar house include direct-gain, heat storing-wall, attached sunspace, storage heat roof and natural convection by the form of heat collection [3]. This paper mainly introduced how the direct-gain passive solar house is applied in the small and midsize public buildings. It makes full use of south windows in the construction directly receiving solar radiation. Through these windows, solar radiation can reach indoor floors, walls and other All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-18/05/16,12:02:43)

2 1430 Trends in Building Materials Research objects directly and rise their surface temperature. And by the method of natural convection heat transfer, part of energy heats indoor air, while the other part stores in the interior of ground, wall etc., making indoor temperature maintain to a certain level. The structure is shown in Fig. 1. Insulating course heat retainer Fig. 1 The Structure of Room Receiving Direct Sunlight When solar radiation exists, south windows in the direct-gain system play the role of gathering solar radiation energy. While there is no solar radiation, they turn into heat dissipation surfaces. Therefore in direct-gain system, south windows should be sized as large as possible, and at the same time, effective thermal insulation measures should be configured, such as insulating curtain. Because the direct-gain passive solar house is characterized by a high thermal efficiency and an obvious indoor temperature fluctuation, it should be applied to room which is required to warm faster or just used in daytime, such as classroom, office, residential and living room etc. If windows have adopted good heat preservation measures, it also can be used for residential bedroom. Owing to the simple structure, direct-gain passive solar house needn t add special heat collection device. With the advantages of faster warming, less investment and convenient management, it will undoubtedly save considerable energy when applied in large number of middle and small sized building [4]. And it can have a significant effect on improving the indoor thermal environment in middle and small-sized building with poor heating situation or even without one. Significance of the application of Solar Energy in the Small and Midsize Public Buildings Most buildings of the cities are still small and midsize ones, which impact the whole building environment of the city directly. We need to pay constant attention to the request made by sustainable development, when the action of saving energy is provided nowadays [5]. Thus, if the energy consumption caused by numerous middle and small-sized construction is minimized, undoubtedly it will play an important role on energy saving in the whole social. The study object of the paper mainly is small and midsize public buildings which scatter across the city relatively. Their building functions often have various types, such as community hospitals, community library and cultural center and so on. The function of internal room of this kind of buildings is relatively simple and people route is organized by plane dominantly. In this part of the construction entity, some appear hot summer and cold winter inside, some have four seasons of constant temperature, and some have broiling winter and especially cold summer indoors. In short, there are a lot of buildings where the comfortable indoor microclimate is not made and the phenomenon of insufficient energy utilization and waste exists. However, there are also some good examples which provide perfect application of solar energy for us. Analysis of these examples can provide reference for us to take adjust measures to special conditions and make a reasonable use of solar energy. Taking the George Street School located in the north of England as an example, this is a direct-gain solar building, it is situated in northern latitude 53.4, and the wall is 70 m long and 8m high. All the glass is double deck glass while the outer is transparent glass and inner lining is the rough diffusion

3 Advanced Materials Research Vols glass packed in the back of transparent glass 600 mm. This is because the diffusion glass can spread more area to the ceiling, floor and the back wall than others. Sunshade board can be packed in the two layers of glass, providing the direct shielding in summer, as well as be used as maintenance access. Heat storage advice are reinforced concrete roof board(180 mm thick), floor slab(230 mm thick), floor(250 mm thick) and brick wall of 230 mm thick. Roof board and the outer of north wall adopt the expansion polystyrene insulation layer (130 mm thick). The continuous testing results about heating condition of the buildings indicated that the buildings gain 70% quantity of heat from solar energy, 22% from light and 8% from human body. The auxiliary heating equipment installed in 1962 has not been used. The success of the building is that it depends on the diffusion of the sunshine for heating in the condition that there is almost no effective direct sunlight. From the George Street school buildings in the north of England we can see that the direct-gain solar house in middle and small-sized public building has a broad prospect. It is a direct reference for us as it can not only save a lot of resources, but also can get comfortable indoor environment. Using passive solar energy technology in middle and small-sized public building can improve the indoor thermal environment, save money, create pleasant indoor temperature, and rich architectural external form, and save a lot of natural resources at the same time, to make the human and nature have a more harmonious development. Application of the Direct-Gain Passive Solar House on Middle and Small-Sized Public Building Location Selection. The buildings should select in the areas where are filled with affluent solar energy resources, and the buildings should not be shielded by hillsides or bushy trees, but should plant some deciduous plants instead, so it will not block the sun lights in winter and will become sun shade and heat insulation in summer. Office rooms Fig. 2. The Atrium in Winter External Form and Internal Room Arrangement. The smaller the building shape coefficient is, the smaller the responding external surface per area is, and the smaller the heat loss of the maintenance structure is.so building with smaller shape coefficient is conductive to reduce the building energy dissipation. However, if the building shape coefficient is too small, it will influence some factors like architectural modeling, plane layout, lighting and ventilating act. Therefore, it is necessary to make a comprehensive consideration about the external morphology, associated with architecture climate zoning characteristics. For the middle and small-sized public building, the composition of the room mainly consider its using requirements, for example, rooms used in daytime like office and classroom should orientate to south, while rooms used in night like bedroom, may orientate to southwest like office and classroom should orientate to south, while rooms used in night like bedroom, may orientate to southwest and the

4 1432 Trends in Building Materials Research declination of which is no more than ±15 also. Atrium can be used as direct-gain passive solar house in some public buildings. The internal rooms arrange around the atrium. In winter, the closed atrium will turn to be a large warm room, becoming thermal buffering part of the large-bay space (as shown in fig. 2). In transition seasons, it is an open space, facilitating perfect air circulation between in and out of rooms, which changes the microcirculation in building efficiently. And in summer, atrium can turn to be a large pergola, as transitional space, to take a good buffer action in the condition when hardly influence air movement in the buildings (as shown in fig. 3). Afforest atrium space in office building can be used as entertainment space, plants in which will improve room air quality in building to create great using atmosphere, and rooms built around atrium can receive light coming from atrium to ensure lighting, with some artificial lighting as assistance, to realize energy conservation. Evaporation Office rooms Fig. 3. The Atrium in the Winter Ventilation. Some dirty air is easy to be produced in the internal space of middle and small-sized building. But most of public buildings take the form of whole enclosure, depends on air-condition to fulfill heating and refrigeration inside the building, and is not set proper amount of windows that can be opened. So the input fresh air quantity is very limited, even with too much energy consumed. It s likely for people to get sick building syndrome when live and work in such environment. But in natural ventilation buildings, this syndrome is kept in a quite low in incidence. So direct-gain passive solar house can mainly adopt natural ventilation, and use other ventilation modes such as thermal pressure ventilation or wind pressure ventilation as supplements. The atrium space in a building, namely direct-gain passive solar house, can be designed as drawing air space. That is to say the warmer air rises inside the building, discharges from the top tuyeres, and the fresh cold air outdoor is inhaled through the building s bottom, leading to an effect that building internal temperature drops meanwhile natural ventilation inside the public building is achieved. This kind of ventilation is thermal pressure ventilation. Wind pressure ventilation is a method that a building should be designed to orientate the summer dominant wind direction, the room depth is shallow (less than 14 meters generally), and the bump on building s outside surface is minimized, so as to help the air flow freely along the outside wall, or to use the sidewall or the wall set across the wind channel to lead the air indoors. In the architecture design work of middle and small-sized buildings, we can consider making a combination of wind pressure ventilation and thermal pressure ventilation. (As shown in Fig.4) Enclosure Structure. The direct-gain passive solar buildings, realize heating mainly through southward window and transparent roof, which is similar to ordinary buildings. The larger the window area exposed to the sun, the more heat it will be got. Meanwhile, some windows absorbing little heat should be cut down as much as possible, to reduce energy loss. Generally the area ratio of window to wall can reach 0.4 and the depth of sunshine can be 2.5 times than the length of window, when southward windows adopt some heat insulation measures. According to this, to control the depth of a room and adjust the height of open windows.

5 Advanced Materials Research Vols Heating top Purification Filter Office rooms Temperature reduction Fig. 4 Ventilating under the Combination of Air Pressure and Heat Pressure The thickness of the glass components themselves in architecture are very small, so in order to improve the performance of the heat insulation of glass, we can use two or three-layer hollow glass. If low emissivity film is attached in the inner layer of the multilayer hollow glass, hot nature will be further improved. Also, if using window with shutter in the glass, the problem of sunshade in the summer is solved. Room temperature can be too high in the summer easily, which is improved by using hollow glass or sunshade glass, or properly by increasing building-higher and promoting ventilation. In daytime, sunlight can warm the room though southward windows, part of it is absorbed by structural component with large thermal capacity, like wall, floor etc (show in fig.5), which let it out to the room at night, keeping a certain temperature to realize heating (show in fig.6). Overhanging sun shield Solar radiation Double-scattering glass Efficient insulation Efficient insulation Double glazing Heat storage material Double glazing Radiation heat transfer Radiation heat transfer Fig. 5 The Situation during the Daytime Fig. 6 The Situation during the nighttime From the roof forms perspective, the sun radiation time and area accepted by the slope roof are higher than by the flat one, and the dome roof is the best one. Taking summer as an example, color and simple sense housetop surface are the mainly controlled conditions, as light color material reflects the sun's rays easily while brunet material absorbs solar heat easily. We can use light color smooth surface coating reflect the sun radiation, or build pool and afforest environment and other effective means on the roof to reduce heated degree. Another flexible installation set can be applied which controls indoor temperature according to seasons, like movable louver or open and close type of roof scuttle etc. The height and shape of the roof is also extremely important, and it can use streamlined and hemispherical roof. All of these measures are beneficial to reduce the wind load when air flows along the external surface of the spherical roof, because it can suck out and discharge of indoor air when the wind reached the fastest speed on the roof. Because the external walls of the building can absorb and store long wave heat of the sun, then radiate out slowly. Through combination of the different heat capacity and thermal conductivity of the thermal storage material or increasing thickness of thermal storage material, we can delay the time of

6 1434 Trends in Building Materials Research the thermal storage radiating heat to the interior. For example, the Wende Fort Youth Education Center, which is designed by Herzog, its exterior wall is composited by different thickness of the several materials [6]. During the day after absorbing the heat, the interval 5 ~ 6 h (midnight when it just starts), heat transfers from the outside surface of the wall to the inside and begins radiating to the indoor. The building interior can keep comfortable and constant temperature within 24 h. A maintenance structure with a good thermal performance can prevent heat entering indoor from outside in summer,and prevent indoor heat leaking out of the room in winter, to keep building indoor temperature comfortable as much as possible. So we can reduce the auxiliary equipment (such as the heating, refrigeration equipment) to achieve reasonable and comfortable room temperature, and finally reach the purpose of saving energy. These measures used in the direct-gain passive solar house of middle and small-sized public buildings, can make it have a better thermal performance. Summary Direct-gain passive solar house can create dulcet internal microclimate in small and midsize public building. Excellent design can make organic combination of architectural design and solar energy utilizing skillfully, which is easy to create flexible and graceful architectural forms.and direct-gain passive solar house owns extensive prospect in middle and small-sized building, because it can save the whole structure energy effectively, can master the technology easily, and also its cost is not too high. References [1] Huang Yue-hai. New Agriculture Vol. 5 (2002), p [2] Wang Chongjie, Xue Yibing: Solar Energy Building Design (China Architecture & Building Press, China 2007). [3] Ren Ziming: Passive solar building design (China Architecture & Building Press, China 2004). [4] Chen Hong, Interior Design Vol. 4 (2000), p [5] Cai Yuping, Yang Guizu. Sichuan Building Science Vol. 33 (2007), p [6] Chen Shilin: Building and Climate and Energy (China Architecture & Building Press, China 1990).

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