PASSIVE AIR HANDLING SYSTEM WITH COOL AND HOT TUBES - APPLICATION AND ITS EFFECTS-

Transcription

1 PASSIVE AIR HANDLING SYSTEM WITH COOL AND HOT TUBES - APPLICATION AND ITS EFFECTS- Takeshi SAKAGUCHI 1 Naoki Nakakita 2 Toshiyuki Sakai 3 1 Building Design Dept., TAKENAKA Corporation Osaka Headquarter, Honmachi, Chuou-ku, Osaka , Japan sakaguchi.takeshi@takenaka.co.jp 2 Building Design Dept., TAKENAKA Corporation Osaka Headquarter, Honmachi, Chuou-ku, Osaka , Japan nakakita.naoki@takenaka.co.jp 3 Building Design Dept., TAKENAKA Corporation Osaka Headquarter, Honmachi, Chuou-ku, Osaka , Japan sakai.toshiyuki@takenaka.co.jp Key Words: Use of ground heat, Under-the-ground ventilation, High Heat Insulation, Outside Insulation, Double wall, Risk hedge, Life cycle CO2, senior citizens SUMMARY This paper introduces Hyakujushi Bank Kokubunji Document Center (Figure 1) as an example case that the passive air handling system with cool and hot tubes as main components is introduced building-wide. The system outline is as follows: heat exchange pipes are installed around GL-3m where the temperature is kept around 15 C throughout the year. The fresh air or the indoor air is supplied to the heat exchange pipes, feeding cool breeze during summer and warm air during winter, respectively. In order to tap the merits of weak natural energy, the high heat insulation is provided by the double wall and double roof,both equipped with the outside insulation. Conventional document storage is not equipped with cooling & heating air handling units to cut the initial cost and the running cost. As a result, operators are forced to work in extreme heat in summer and in bitter coldness in winter. The project client indicated their intention to hire senior citizens for the operation addressing the aging society with low birth rate. In turn, cool breeze and warm air ventilation system enabled by cool & hot tubes is introduced. According to the measurement results, the indoor temperature during the summer peak time was about 28 C and that during winter peak time was about 16 C, respectively, which realizes the comfortable in-door environment for the senior citizens to work without the heating/cooling air handling units. Figure 1 Building Appearance

2 1. INTRODUCTION 1.1 Background For the sustainable world, the global environment consciousness is now recognized as one of corporate value scales. Accordingly, the clients and operators actively involved in introducing the environment technologies are now emerging. It is projected that the active use of senior citizens such as ex-employees of the companies is indispensable in the future due to the aging society with less birth rate in Japan. 1.2 Procedures of Introduction of Passive Air Handling Systems with Cool & Hot Tubes Reflecting these social background, the client raised two requests: 1 Senior citizens are hired for storage keeping job 2Client wishes to contribute to the global environment. These requests were considered and the various air conditioning systems were compared. (Figure 2) Method W/O A/C Spot A/C General A/C Draft Ventilation Cool & Hot Tube Scheme A/C units A/C units Cold breeze (summer) Tap stack effect to Cooling/Heating and hot air ( winter) take the chilled air supplied via under the Outline No A/C for the limited A/C for all area from lower area and ground where the exhaust heat from temperature is stable area upper area throughout year Comforts Should be patient Unstable A certain comforts is Should be patient Comforts is in summer and depending on the available throughout ( for Senior) in not A/Ced area guaranteed winter climate conditions the year Small maintenance Big maintenance Maintainability Not required Nearly not required Nearly not required score score Limited number Full set of Under-the-ground Initial cost Zero Draft shaft of A/C units A/C system tubes, shaft, s Limited electric Normal electric Electric power cost Running Cost Zero Zero power cost power cost of s. CO2 Emission No Small Big Zero Very small Figure 2 Air Handling System Fitting Document Storage Generally speaking, the document storage has large acceptable range in the comforts in comparison with that in office, hotel, hospital or commercial facility. On the other hand, as the storage does not directly accrue the profit, low running cost is required for the document storage. As a result, generally in document storage, there is no air conditioning or spot air conditioning, which forces the operators to work in the extream heat in summer and in bitter coldness in winter. In case of this Document Center, upon the client s request on the use of the senior human resource, the indoor environment enabling the senior citizens to conduct the storage keeping jobs comfortably is realized tapping the environment technologies, cold breeze & hot air ventilation system with the cool & hot tubes.

3 2. Air Handling System with Cool & Hot Tubes as Main Components 2.1 System Outline The outline of the passive air conditioning system with cool & hot tubes as main components realized in Hyakujushi Bank Kokubunji Document Center completed in June 2004 in Kagawa prefecture is as follows: the heat exchange pipes are installed about 3m under the ground, where the temperature is kept around 15 C throughout the year, the fresh air or indoor air is supplied to the heat exchange pipes for the thermal exchange with the under-the-ground heat for the supply of cool breeze during summer and hot air during winter, respectively, to the room interior. At the same time, learnt from Dozou, the traditional mad-made storehouse in Japan, the peripheral technologies and design are arranged so as to tap the natural energy to the maximum extent with the high heat insulation embedded in the exterior wall and the roof together with the minimum opening with eaves. 2.2 Cool & Hot Tubes Cool & hot tubes introduced in the Document Center are consisted of 3 systems, for the office (1/F), Storage (1/F) and Storage (2/F). All three systems are to take in the fresh air via the heat exchange pipes installed beneath the building. The internal circulation system is also available, which does not take in the fresh air and re-supply the indoor air to cool & hot tubes for heat exchange under the ground. The fresh air intake or internal circulation can be selected by switching the dampers. (Figure 3,4,5) roof-top heat buffer (cement board) air layer insulation material air layer storage(2/f) insulation material wall heat buffer (hollow cement board) dampers storage(1/f) dehumidifier GL cool &hot tubes Figure 3 Cool & Hot Tube System As an example, the system specification of the system for Storage (1/F) occupied every day is as follows: Material : VU pipes (vitrified vinyl chloride) Diameter : 600 mm Installation Depth/Length :17.3 m-long pipes at 1.2m under the foundation 44.2 m-long pipes at 2.9m under the foundation (installation depth is measured at the pipe center) Air Volume : 1,700 kg/hour Operation Mode of Fans : Automatic on/off of s depending on the indoor temperature

4 Switching fresh air intake and :Automatic switching of dampers depending on the dew point of the fresh air Operation of dehumidifier : Automatic ON/OFF of compressors depending on the indoor relative humidity. air supply Exhaust air storage(2/f) Internal circulation storage(1/f) air supply cool &hot tubes Figure 4 section Figure 5 Installation of Cool & Hot Tubes 2.3 High Insulation Performance In order to maximize the benefits of the natural energy obtained with cool & hot tubes, the exterior wall and roofs are embedded with the high heat insulation performance. The exterior wall is the double wall with the outside insulation ; paste 25mm-thick insulation material on the exterior face of the concrete wall and fix the hollow cement board in the dry method on its exterior with 90mm ~ 240 mm thick air layer in between. (Figure 6)

5 The roof is the double roof with the outside insulation ; provide the water-proofing layer on the concrete floor pasted with 50mm-thick, then the cement board is installed with clearance for the air circulation while maintaining 17mm with the short posts (Figure 6) roof-top heat buffer (cement board) air layer insulation material exhaust air wall heat buffer (hollow cement board) air layer insulation material air circulation Figure 6 Exterior Wall and Roof: Partial Details 2.4 Risk Hedging The next generation technology requires the client s progressive understanding. To respond to their understanding, the following two points are considered to hedge the risk in case cool & hot tubes do not function satisfactory. In case cool & hot tubes cannot be used due to the watering, massive mold or cutting by earthquake, the ventilation route is secured with the standby grilles and ventilation shaft to take in the fresh air on the roof-top. The fresh air taken in via the cool & hot tubes during summer time is expected to increase the relative humidity due to the cooling effect. Accordingly, in order to prevent molds or insects accrued on the document stored in the Storage due to the increased humidity, the dehumidifiers areinstalled, which are automatically started in the relative humidity of 70% or higher. 3. Verification of the Effects 3.1 Computerized Measurement System This Document Center is equipped with the computerized system to measure the temperature, humidity, ventilation air volume and used natural energy every hour at various points. The measured data are collected for the future verification of the efficacy as the environment technology. (Figure 7) Measure the temperature, humidity, and dew point of the fresh air in the outdoor ventilated case for meteorological instruments. Measure the temperature of the in-take fresh air at the entry of cool & hot tubes Measure the indoor temperature and humidity, temperature and volume of air supply in the Storage Measure the under-the-ground temperature (at three points: 3.4m, 3.2m and 1.0m beneath the foundation)

6 sensor of flow rate sensor of flow rate of supply air supply air dehumidifier supply air of supply air dehumidifier storage(2/f) storage(1/f) hygrometer damper damper damper damper exhaust air exhaust air hygrometer dew-point hygrometer air shaft hygrometer supply air the under-the-ground temperature sensors cool & hot tubes of supply air Figure 7 Computerized Measurement System 3.2 Summer Time Data (July 4, 2004) The internal circulation is operated as the under-the-ground temperature is stable at 16.5 while the fresh air exceeds 35. The temperature of the supplied air is stable around 25.5 and the indoor temperature is stable around 28. (Figure 8) 40.0 outdoor under-the-ground supply air indoor temperature( ) time Figure 8 Summer Time Data

7 3.3 Winter Time Data (January 2, 2005) Under-the-ground temperature is stable around 20 while the temperature of the fresh air is -1.8 in early morning and 9 during day time. As the fresh air temperature is extremely low in comparison with the indoor temperature, the internal circulation system is in operation. At 9:00, the work starting hour, the indoor temperature is 16 while the fresh air temperature is 2.8. This is the favorable result. (Figure 9) 25.0 outdoor under-the-ground supply air indoor 20.0 temperature ( ) Figure 9 time Winter Time Data 4. CONCLUSION As indicated in the measurement results, the indoor environment enables the comfortable storage job even for the senior citizens during summer, transitional period, and winter without the air conditioning system. It is half year since the passive air system with cool & hot tubes started the operation. And the system is operated daily without troubles as the system is simple. The following points are identified in our approach to introduce the cool & hot tubes and to provide the high insulation to maximize its effects: The environment technologies in next generation requires to share the framework of the social background, cost, reliability, and risk hedge measures in the pre-design phase among the client, the operator, and architects/engineers. The operation phase is positioned as post-design phase to feedback the operation data to the client, the operator, architects/engineers in order to verify the optimum operation mode, which advantages should be shared by the client and the operator for the development and proliferation of the next environment technologies. The political commitment to provide the public system to facilitate the client s involvement in the eco conscious activities and to set the higher target as a part of the environment policies. In July 2005, one year of operation, temperature,humidity,the energy volume, generated CO2 and other measurement data throughout the full year will be available. Those data will be presented in SB05 Tokyo in the end of September.

8 5. REFERENCES Hamada, Y. 2004, edited by JIA, Part II Use of under-the-ground heat, Volume 2 of Global Environment Architecture, Technical Part Resource, Energy, and Architecture, Japanese, Shoukokusha Inoue, U. edited, 1976, Basic Planning of Architectural Facilities: Planning and HVAC/M&E, Japanese, Maruzen Taisei Corporation HVAC/Sanitary Facility Research Group, Practical Data Book on HVAC/Sanitary Design, Japanese, Kasuga-shobou Horikoshi, T, 2003, Passive Architectural Design Method Dictionary to use Natural Energy, 29. Use of Under-the-ground Temperature, Japanese, Shoukokusho