Kowhai House Dunedin

Project Team

Architecture & Passive House Design Rafe Maclean Architects Ltd – www.rafemaclean.co.nz
Construction Stevenson & Williams Ltd - eHaus Otago Licensee– www.stevwill.co.nz
Structural Engineer Ezed Ltd – www.ezed.co.nz
Certifier Sustainable Engineering Ltd – www.sustainableengineering.co.nz

Kowhai House was designed by Rafe Maclean as his family home. His family wanted a warm house after experiencing the state of rental houses in Dunedin. Like many of us several members of his family have asthma making clean air and warmth a health priority. On calm days in the winter in Dunedin, you can see and smell the coal soot outdoors from home heating but with the filtered fresh air from the MVHR this pollution is kept out of their home.
The simplicity of the homes form helped to reduce construction complexity while making the home more thermal efficient.  Keeping the car parking away from the home has become an enjoyable feature. Although the spaces in the home are small there are enough of them to allow the family members to have their own space and privacy.
The site is steep so a structure on piles was used to navigate the difficult terrain and a prefabricated SIP panel construction was adopted to reduce time on site. Windows were fabricated locally in Dunedin by Thermadura. This was the first Passive House constructed by the builders and achieved an excellent air leakage result.

Passive House Metrics

  • Heating Demand 15 kWh/m2/year
  • Heating Load 8 W/m2
  • Frequency of Overheating7.8 % year over 25°C
  • TFA 117 m2
  • Form Factor3.2
  • Air leakage @ 50Pa0.1 ACH/hour
  • PER demand48 kWh/m2/year

Passive House Database 5662

Construction Details Average Values

  • U-value External Walls0.16 W/(m2K)
  • NZSIP plus internal insulation
  • U-value Floor0.18 W/(m2K)
  • Timber with Terra Lana insulation
  • U-value Roof0.12 W/(m2K)
  • NZSIP plus internal insulation
  • U-value Glass0.55 W/(m2K)
  • Triple
  • U-Windows0.87 W/(m2K)
  • Thermadura Natureline 90
  • Ventilation Efficiency82.51%
  • Zehnder Q350