The detailed statistical analysis was conducted in terms of the electricity use by air conditioners (A/Cs) in residential buildings according to the time-series data of electricity consumption. These data were observed for two years with an interval of 1 min in more than 500 dwellings at a residential building complex located in Settu city, Osaka, Japan. The analysis revealed the strong diversity of the amount of electricity consumption and the dependency of the outdoor thermal condition on the frequency of A/Cs among households. In addition, both the diurnal and annual cycles of A/C usage were shown. Furthermore, the derived probability density distributions of the A/C load for each dwelling demonstrated variation among households, and suggested the difficulty in universally modelling their features even though the A/C was scaled using the average of A/C load.

Recently, simulations of a heat pump water heater have become popular for its performance evaluation. There are several numerical methods for estimating the temperature distribution of a hot water storage tank. However, in general, the numerical methods require an extremely long computational time. For example, the numerical method developed by Wakamatsu and Hashimoto (2013) requires needs approximately 1 h to compute temperature distribution inside a hot storage tank of a heat pump water heater for 1 year. The numerical method developed by Wakamatsu and Hashimoto (2013) uses an artificial limit of flow per time step in the process of hot water supply and water heating to make programing easy. This restriction has a disadvantage that its computational cost is too high to use for tools of sales promotion of the heat pump water heater. Therefore, we developed new numerical methods for hot water supply and heating water without this restriction. First, in order to check the accuracy of the numerical methods, we compared numerical results computed by the method developed by Wakamatsu and Hashimoto (2013) with those of the new methods. It was revealed that the accuracy of the new numerical methods with 20 grids is acceptable. Second, to check the computational time of the numerical methods, we compared the computational time computed by the method developed by Wakamatsu and Hashimoto (2013) with those of the new methods. We determined that the computational time of the new numerical method is greatly reduced. Finally, it was revealed that new numerical methods for heating water and supplying hot water are suitable for fast computation.

It is desirable for high-rise office buildings to use a double-skin facade (DSF) and other high-performance solar radiation shielding methods as a measure against global warming. As a design tool, air-conditioning load-calculation methods have been developed that are based on numeric models using the solar heat gain coefficient (SHGC). However, no method has yet been developed to investigate the SHGC of completed buildings to ensure that the performance follows the design specifications. Another difficulty is that the completed buildings must be measured without the use of large testing equipment that would inconvenience occupants. Thus, our aim is to develop a fast and easy method for measuring the SHGC. Recently, solar spectroradiometers, which are designed to evaluate solar cells, have become small enough for handheld portability to construction sites. We use two of these spectroradiometers to simultaneously measure the indoor and outdoor solar radiation intensities on either side of a façade, and calculate the SHGC based on the ratio. The measurement range for small spectroradiometers is 300–1100 nm, which covers approximately 80% of the solar spectrum distribution. Furthermore, with venetian blinds, separate glass windows, and a building interior such as a DSF, the far-infrared re-radiation due to reflection from blind slats is blocked by the transmission characteristics of the glass, this makes measurement unnecessary. The results showed that, when the small spectroradiometers were used to measure the SHGC of multiple glass samples with known characteristics, the proposed method properly reproduced the coefficients. We then used the spectroradiometers to measure a building with a DSF and determined that the proposed method is well-suited to field measurements.

To we plan a district heating and cooling system, improvement of the standard of load densities for various types of buildings existing in the area is indispensable. In addition, the use of unutilized energy is advantageous in the promotion of energy saving. However: the generally used standard of load densities for buildings is based on data of the last 20 years. Thus, we provide a database update by the use of DECC data of the 2000s in this paper. Thus, we provide a database update by the use of DECC data of the 2000s in this paper. In this, we establish systematically 10 building load type and regions and the proposal is compared with those reports in the past. For unutilized energy, we put together six kinds of the data source and processing method to get the temperature and available amount (flow quantity, heat capacity).