TOPICS

Geothermal Application for Building

MUKAI Akiyoshi, Director of Building Department
ASHIE Yasunobu(Dr. Eng.), HeadNISHIZAWA Shigeki(Ph.D(Eng.)), Senior Researcher
Environment and Equipment Standards Division, Building Department(KEYWORDS) Renewable Energy, Earth Thermal Application, Energy

Heating & Circulation

地中温度およびUﾁｭｰﾌﾞ入口出口温度（℃）

[°C]
2525

Restitution
Inlet Temp. of U-Tube
Outlet Temp. of U-Tube452020151535

Ground Temp.
(depends on depth)

25

[°C]
15151010Air Temp.
5500002012/3/8
11:18開始

55102030304050607080901006090経過時間(hour)
Elapsed Time[hour]

1101201301202012/3/10
23:18開始‐5-5140

2012/3/14
9:00終了Fig.1 One trend of thermal response experiment
3. Conclusion
The experiment which uses geothermal for air-conditioningof a building isconducted, and the efficiency of the heat pumpsystem with geothermal use will be examined. Hereafter, theestimation method of energy saving effect is built based onthese observations.
【Reference】
1) Technical information about the energy-saving standard ofresidences and buildings, and the authorization standard ofa low carbon building (In Japanese)
http://www.kenken.go.jp/becc/index.html

Air Temp.

Ground Temp. and Inlet/Outlet Temp. of U-Tube

2. Experiment of Geothermal Application
Various technologies have been developed for the use ofgeothermal energy as a function of the period (daily or yearlycycle), usage (directly or as heat source of heat pump) andgroundwater level.
The information of developmental status about thetechnologies have been organized, and the experiment isconducted to evaluate energy saving effect of heat pumpsystem with geothermal use. Two U-tubes (inside diameter:25mm) were installed in the ground to a depth of 50 meter(Photo 1), and thermal response experiment has been
conducted to check the heat exchange performance between
soil and water in tubes (Fig. 1). And heat pump with the watersupply from U-tubes as heat source is installed for
air-conditioning in the experimental room, and the energy
saving effect of heat pump system with geothermal use is
examined compared with general air-conditioning system
which will be installed in another room which is kept in same
condition.

Photo 1 Installation of the U-tubes

気温（℃）

1. BackgroundThe carbon-dioxide emissions from residences andbuildings show the upward tendency every year, recording of
31.9% increase in the business sector, and 34.9% increase in
the residential sector in the fiscal year of 2010 (comparedwith 1990).
For saving energy of residences and buildings, the low
carbon building authorization standard was promulgated in
December 2012, and the energy conservation standards arerevised based on the estimation of primary energy
consumption. Although this method is introduced to estimate
the energy saving technology of building envelope andequipment comprehensively, some renewable energy
technology (geothermal use and so on) is not evaluated. It isnecessary to evaluate the technology on the same frameworkof the estimation method of primary energy consumption
In theresearch on “introduction of new technologies forbuildings with a focus on the renewable energy (2011-2013)",the estimation method is developed from the experimental
evaluation about renewable energy technology (solar energy,geothermal energy, etc.).