Sihwan Lee, Shinsuke Kato, Kyosuke Hiyama, Daisuke Kawahara, Yoshikazu Nomura, Yutaka Oura, Katsuhiko Mori, Satoshi Sawaki
Bibliographic info:
33rd AIVC Conference " Optimising Ventilative Cooling and Airtightness for [Nearly] Zero-Energy Buildings, IAQ and Comfort", Copenhagen, Denmark, 10-11 October 2012

It still remains heat loss and high risk of moisture condensation occurrence at glass of window because they have relatively poor insulating qualities and usually contribute the greatest heat loss by heat conduction in residential buildings. Although many attractive window systems are proposed to reduce heat loss such as double and triple glazing, low emissivity film coated glazing, argon gas injected glazing, vacuum insulated glazing, double-pane and triple-pane window etc., it has also demerits such as high initial cost and indoor air quality problem. To solve these problems, this paper propose air supply type airflow window system applied to double-pane window combine with a mechanical ventilator and a heat-recovery heat pump system.
The aim of this paper is to evaluate the thermal insulation efficiency and probability of moisture condensation in the air supply type airflow window system applied to double-pane window combine with 2 double glazing using numerical simualtion in order to confirm its feasibility and applicability in residential buildings. First, the proposed system is designed to ventilate through the air space of a double-pane window combine with 2 double glazing. Then, to verify its thermal insulation efficiency, the temperature distribution of the glass of window was evaluated using computer fluid dynamics (CFD) with a coated position of low emissivity film, after confirming calculation accuracy using double-pane window model, double glazing, and low emissivity film coated glazing. In addition, to verify the probability of moisture condensation, the dew-point temperature in the glass of window was calculated based on the various low emissivity film positions.
The calculated results show the thermal insulation efficiency of the proposed system is enhanced approximately 25.48% and 62.95% by airflow effect in comparison with the double-pane window and single-pane window with double glazing. Moreover the calculation results show that it is effective to use low emissive film in the proposed system to avoid moisture condensation occurrence. Therefore, it is confirmed technically feasible to reduce the energy consumption and to avoid moisture condensation occurrence the in residential buildings.