According to the local climate in Auckland, New Zealand, a house does not normally need any active cooling controls such as air conditioning or ceiling fans during the summer. Temporary heating is mainly needed during the winter night. In addition, winter daytime window ventilation is required to remove moisture arising from daily occupant activities. A previous study (Su, 2008) showed that additional winter energy consumption is needed for space heating, for hot water heating and for other appliances that are impacted by the winter conditions. Winter energy consumption is also a large portion of the annual energy consumption of Auckland houses. This study focuses on the impact of building passive design on housing annual energy consumption. The quantitative relationships between building design data and annual energy consumption data are valuable for developing passive design guides for housing energy efficiency. This paper shows how energy consumption can be reduced by optimizing wall and roof design resulting in between 40 - 70% reductions in energy demand from 2000 levels.