PGG Wrightson Seeds

The Challenge

When designing the facility, the Property Developer Ngai Tahu was looking for a heating and cooling solution that was both green and energy-efficient. The relatively small size of the building meant a traditional VRF solution was a good fit however the potential environmental impact of such a system was a key consideration in the decision-making process.

The Solution

Because of the significant reduction in the amount of refrigerant required in the overall system, Mitsubishi Electric’s unique City Multi Hybrid VRF (HVRF) Hydronic Heat Recovery System and high-efficiency outdoor units were specifically chosen to provide the energy-efficient heating and cooling needed for this state-of-the-art office complex.

A key reason Hybrid VRF was chosen is that water instead of refrigerant is used between the Hybrid Branch Controller (HBC) and each indoor unit. As a result, occupant safety was maximised because the risk of refrigerant leaking into small occupied spaces was now mitigated. Furthermore, because of the significant reduction in refrigerant required in the overall system, a noticeable refrigerant cost saving was able to be realised.

Furthermore, the Hybrid VRF 2-Pipe System offered the same heat recovery benefits and the small footprint flexibility normally associated with traditional VRF.

High-efficiency outdoor units were used to achieve greater EER’s and COP’s, further reducing the operating power consumption of the building. Mitsubishi Electric EP units achieve this energy-efficient performance by using an aluminium flat tube in place of the traditional round copper tube in the outdoor unit heat exchanger. As a result, this allows for an increased number of tubes and significantly more surface area within the outdoor heat exchanger in the same footprint, improving the heat exchange effectiveness.

Mitsubishi Electric Lossnay Energy Recovery Ventilation Systems were also integrated into the design to provide the fresh air requirements to the building. The Lossnay’s ability to recover the sensible and latent heat ensures that as much energy is kept within the building, further reducing the operating power consumption of the facility. In addition to this, the transfer of the latent component also ensures that the humidity is maintained within the space. Each Lossnay System features an inbuilt bypass damper to enable the utilisation of free cooling. This is facilitated through the M-NET Control System that interfaces each Lossnay System with the associated air conditioning unit.