In 2024, Simx supported a student-led renovation of a 1970s ex-Kāinga Ora state house, supplying a SmartVent Balance mechanical ventilation system for the One Tree Hill College Trade Academy’s $1 state house project. The initiative gave students hands-on trade experience and introduced best-practice principles for building healthy, energy-efficient homes.

Ventilation was an important consideration in the project, helping to manage internal moisture, improve indoor air quality, and reduce the risk of overheating during summer months. To achieve the targeted Homestar v5 Level 7 goal, the renovation required a continuous mechanical ventilation system that could operate efficiently within the constraints of an existing building envelope.

The project presented several challenges. As a retrofit, the home had fixed architectural elements such as a limited wall cavity depth and fixed window positioning. Additionally, its status as a transportable home introduced uncertainties around factors such as building orientation and airtightness — key influences of the home’s energy-efficiency and Homestar rating. In response, Simx worked alongside the project’s Homestar assessor and designer to adapt the original specification to better suit the project’s goals.

A SmartVent Balance system was selected for its ability to deliver high-performance mechanical ventilation with heat recovery (MVHR). The system automatically draws in fresh, filtered air and recovers up to 90% of heat energy from outgoing stale air. A summer bypass mode enables passive cooling when outdoor temperatures allow, and the system also provides bathroom extraction, reducing the need for a separate fan system. The compact heat recovery core made the Balance suitable for the spatial limitations typical of retrofit applications.

To further enhance energy efficiency and occupant comfort, the system was integrated with the home’s ducted heat pump. This allows consistent airflow at a comfortable temperature with minimal operational costs and is possible in both retrofit and new-build projects.

The system was installed in October 2024 and commissioned in February 2025. Since then, it has effectively reduced internal moisture, mitigated overheating, and improved overall occupant comfort year-round. The house was sold in May 2025, with proceeds supporting future hands-on student building projects.

When you have a difficult project involving a ventilation system, SmartVent has a free ventilation design service available to help.

This service is designed to help specifiers:

• Navigate complex retrofit or new-build ventilation constraints
• Achieve desired ventilation performance targets and goals
• Ensure relevant code compliance

Get in touch with the Simx to learn more