بهبود محیط حرارتی و کاهش مصرف انرژی برای سرمایش و گرمایش توسط پنجره های مقاوم سازی

Various techniques for creating a comfortable thermal environment and saving energy have been proposed and employed in residential buildings in many countries, including Japan. For these techniques to be introduced, existing houses should be renovated. Among the techniques available, installation of additional inner windows is effective in creating a comfortable and energy-efficient living environment. In the present research, the effect of additional inner windows on the thermal environment and energy saving was investigated by measuring indoor climates. Windows were renovated in two rooms on the fourth floor of a four-story reinforced concrete building. Air temperatures, the humidity, the global solar radiation on horizontal and vertical surfaces, radiant temperatures, and the electricity consumption of air-conditioners were measured. A comparison of these values before and after the installation of inner-windows showed that the thermal environment and energy saving had improved. Results obtained from a thermal model agreed well with measured results by changing the value of solar transmittance and heat transmission coefficient of the glazing following renovation. Furthermore, in a questionnaire survey conducted in summer, more than half of the occupants answered “comfortable” to a question on the overall thermal comfort.

Various techniques for creating a comfortable living environment and saving energy have been proposed and employed in residential buildings. Among the available techniques, the installation of additional inner windows appears promising for creating a comfortable and energy-efficient living environment in existing houses. Since the outdoor temperature and solar radiation significantly influence the indoor thermal environment through openings, window renovation will improve the indoor climate and reduce the cooling and heating loads. As related research, Ismail and Henriquez (2005) investigated double-glazed windows with a ventilation system. Garvin and Wilson (1998) studied the influence of double-glazed windows on the indoor environment. Arici and Karabay (2010) attempted to determine the optimum thickness of double-glazed windows. Double-glazed windows were also investigated by Aydin (2006), Gordont (1987), and Carlos et al. (2011). Hayatsu et al. (2009) and Sakamoto et al. (2009) reported the effectiveness of inner windows on the basis of measurements and a simulation. However, it is important to evaluate the effectiveness of the inner windows in various situations since their effectiveness depends on the airtightness, the lifestyle of the inhabitants, and many other factors. In the present research, the effect of additional inner windows on the thermal environment and energy saving in both summer and winter was investigated by measuring differences in the indoor climates, electricity consumption, and the thermal sensation of the occupants before and after the installation of the inner windows.

In order to investigate the effectiveness of inner windows in reducing energy consumption and improving the thermal environment, windows were renovated in rooms on the fourth floor of a four-story reinforced concrete building. The room air temperatures were slightly decreased upon installing inner windows in summer, but it was difficult to evaluate their effectiveness, since the outdoor temperature and the operating period of the air-conditioners were different before and after installation. In order to clarify the effectiveness of the inner windows, a thermal model was developed to calculate the room air temperature and energy use. The results obtained from this model agreed fairy well with the measured results by decreasing the value of heat transmission coefficient of the glazing. This indicates that the energy consumption and the room air temperatures decreased because the inner windows prevented solar radiation and heat flow from the outside. Furthermore, a questionnaire survey was carried out in order to examine the subjective evaluation of occupants. Judging from their response, the thermal environment was improved after the installation of the inner windows, with over half of the respondents answering “comfortable” to a question on the overall thermal comfort. In winter, the room air temperatures decreased upon removing the inner windows. The results obtained by using the same model agreed well with the measured results. The questionnaire survey also showed the improvement of the thermal environment by the installation of the inner windows. Overall, the installation of the inner windows improved the thermal environment, both in summer and winter.