Passive Prefab: Better homes faster?

Housing in New Zealand is severely unaffordable, with the average house value almost ten times the average household income. Construction delays, material and labour shortages, long consent times and significant price increases are contributing to the affordability issues. Add to this, much of New Zealand’s existing housing stock is no longer suitable, with unhealthy interior environments increasing disease occurrence and creating uncomfortable interior spaces that require large amounts of energy to heat. Affordable housing that meets the physical, social, cultural and psychological needs of inhabitants is required. Responding to these concerns, this thesis aims to develop existing prefabrication systems to Passive House standard to improve the affordability and health of new homes in New Zealand.

The research examines high-performance, prefabricated architecture through theory, design experiments and the design of a single typology applied to two different situations. The project aims to propose a prefabrication system that meets Passive House, requires minimal large equipment and provides healthy, affordable homes. Through thermal bridge modelling and energy use simulation, an existing prefabrication system will be developed to Passive House standard. Using the constraints discovered through this process, a single dwelling typology was designed and applied to two situations: a standalone dwelling and four attached townhouses.

Analysis of the proposed solution found that the design does meet Passive House requirements assuming all post-design criteria are met. It also found that achieving Passive House,whilst possible, may not be the best solution to the problem. Increasing the availability and performance of the system to a level that far exceeds current and proposed New Zealand Building Code requirements provides significant benefits for the health and affordability of homes without the additional costs of Passive House certification could be a viable middle ground.