Abstract
After the Tohoku Earthquake in 2011, energy saving strategies in all fields is has become an urgent issue. It is essential to have drastic overall power savings, including energy saving during peak usage times, continuous less environment impact. Specific examples of energy saving policies in operation such as the decommissioning of equipment and use of low intensity illumination sources have been conducted and effects have been obtained. Another route to energy conservation is the strict temperature control of Air Conditioning (AC) units in buildings. The effects of the increase in temperature during warm weather makes productivity and work efficiency lower, so it is desirable to balance energy savings with worker comfort levels. 40% of the total energy usage in office buildings is consumed by the air conditioning system. Optimizing the efficient use of AC system should result in a stable indoor thermal environment while contributing to energy savings.
It is very important to focus energy savings on small and medium sized buildings because more than half of the total floor space in Japan is occupied by small and medium sized buildings which are less than 2000m2. It is necessary to find out the type of heat generation load at the time of operation for small and medium sized office buildings and determine the optimized AC plan before starting the design of the building. However there are not many cases that measured AC heat generation of each individual room and determined the AC load.
In this study we looked at small buildings in the Shikoku area which used multi-packaged air conditioners steel framed buildings of similar size and with the same equipment specifications in Kochi prefecture was measured. The purpose of this research is to develop a basic data set that will contribute to the construction of optimal air conditioning designs and operation techniques that lead to energy conservation and cost savings.
The results obtained in this study are as follows:
1) The measured value of the indoor temperature is lower during winter and higher during summer when compared to the system's design value. This confirms that the Warm Biz, Cool Biz directives to tighten the office temperature values to conserve energy are being followed. And the CO2 concentration detected was within the health management standards during both heating periods and cooling periods.
2) During heating periods there was a large deviation between the designed capacity of the system and the measured value. The integrated value of the maximum amount of heat treatment for heating rated capacity was 158.0kW as opposed to the measured value of the maximum amount of heat was 45.9kw.
3) During cooling periods, we found that for the AC system rated for 152kw heat storage utilization the integrated value of the measured value of the maximum amount of heat generation was 51.3kW. Even on the hottest day of the year the system was operating with only 30% of the utilization capacity.
4) We hypothesize that the cause of the difference of the air conditioner heat source capacity and the maximum amount of heat processing in already installed systems is coming from the difference in a given condition of AC load at the time of design. It is necessary to estimate these causes in detail and develop design documents for future guidance.
