A project examining sustainable retrofit of existing homes in Papakowhai was undertaken from 2006-2008. Nine homes were renovated with a range of sustainable interventions and monitored to see the effects of the retrofits on dwelling performance. During the course of the project, nine reports on different aspects of the project were prepared. This report summarises these reports and presents the overall findings, with a case study for each house.
Key findings were:
- Full thermal envelope insulation is likely to be needed if reticulated energy savings and temperature improvements to HSS-2006 standards are to be made.
- Efficient heating must accompany insulation improvements.
- Hot water cylinder wraps are an excellent investment across all hot water cylinder grades.
- Optimally-sized and -installed solar hot water systems can deliver high efficiency even in winter.
- A number of retrofit measures are relatively straightforward and can easily be included within a wider renovation by competent tradespeople – although specification and correct sizing needs to be carefully undertaken.
- Some measures are slightly trickier and due to their currently uncommon occurrence (rainwater plumbed for internal uses, greywater reuse, retrofitting double glazing) need specialist installers with a high degree of competence and familiarity with good installation practices.
- Careful planning and project management are required to ensure an optimal renovation outcome – from both the consumer perspective and good function of the interventions.
- Good management of consenting issues is critical to implementing large scale renovations.