Study on the night-time ventilation for cooling the building having thick walls with outer insulation

Hokkaido is distinguished from the other island of Japan by having colder winters and cooler summers. The average monthly minimum is about -10 °C and summer daily average maximum around 25°C, so that efficient space heating becomes the dominant aspect But on hot days the temperature may reach 35°C, though for short period of time. There are few houses constructed to prevent overheating ID summer. I have designed and built a house for my family ID Sapporo which has cavity walls of concrete blocks insulated with urethane 100mm thick and deeply recessed, but operable widows. I detected the thermal performance of my house to solve overheating problems at design stage.