Rehua, University of Canterbury

The Rehua project involved the complete strip out, strengthening and re-purposing of the existing Commerce Building located within the University’s campus following the Canterbury earthquakes. The decision to retain and strengthen the existing structure was largely influenced by the Universities sustainability principles and wanting to reduce the amount of construction waste and demolition around campus where possible. In order Powell Fenwick was responsible for the Mechanical, Hydraulic, Electrical and Civil services for this project.

The strengthened and re-purposed building effectively required a second structure to be built within the existing to increase it to near 100% of the NBS. The additional structure, in conjunction with the more intensely occupied spaces provided a number of services challenges and required the design team to work cohesively with regular model swaps and check points to ensure the design coordination and corresponding cost estimates completed at each milestone were as accurate as possible ensuring the project remained within what was a tight budget.

The new function of the building consists of lecture theatres/learning spaces, open plan office areas, individual meetings rooms as well as a Café and informal meeting/learning spaces. As the building was re-purposed for a much larger occupancy particular emphasis was put into the façade design to minimise the impact of external heat gains in order to reduce the required HVAC plant physical size and capacity. This included energy modelling of the proposed glazing and external shading to determine the impact of various options in order to ensure the best long term cooling and ventilation systems were installed with consideration for both the capital (in terms of HVAC plant as the façade) and on-going running costs for the University being a long term owner/operator.

Heating is provided from connection into the site reticulated boiler sourced medium temperature heating water system which provides heating to central air handlers located in plant rooms distributing tempered and fresh air and localised radiant heaters located throughout the building as required. A new high efficiency magnetic bearing chiller was installed in the basement plant room to provide the additional cooling capacity required to meet the re-purposed buildings requirements whilst having the benefit of providing any excess capacity into the site’s Science Precinct chilled water ring main which services multiple buildings.