First Light Batch

The Challenge

Since 2002, the US Department of Energy has run the bi-annual Solar Decathlon, consisting of 20 university teams chosen from around the globe. 2011 saw Victoria University of Wellington’s First Light team selected as the only entry, ever, from the southern hemisphere.

To compete, each team is tasked with demonstrating innovative clean-energy solutions by designing, constructing and showcasing a solar-powered house. The teams are then judged over 10 contests from architecture to market appeal, comfort zone and energy balance.

Taking this opportunity to showcase NZ’s bach culture, the First Light team needed to design and build a bach which exhibited strong kiwi values (combining a strong connection with the landscape, a hands-on ‘do it yourself’ mentality and outdoor socializing) without compromising on the need to be a net zero dwelling (i.e. produce at least as much energy as it uses). Not only this, the house had an expectation to maintain a uniform temperature between 22.2°C and 24.4°C as well as a relative humidity less than 60% throughout the 3 weeks it was on site.

The Solution

The overarching objective was to meet the necessary net zero requirement. To achieve this, the team turned to the installation of 28 highly efficient 225W Mitsubishi Electric Photovoltaic Solar Panels, allowing a maximum output of 6.3 kWh. These solar panels can be used either as part of an “on-grid” or “off-grid” system. Used “on grid”, they are so efficient they can produce more power than needed for the First Light bach. This extra energy can then be redirected back to the grid. When used off-grid the extra energy generated in months with greater sunshine hours can be stored in a battery bank and then recycled for use in months with reduced sunshine. With the Energy Balance contest judging houses based on their ability to achieve a net zero balance, the First Light house gained the maximum 100 points.

In order to service the house’s temperature and humidity needs the house was fitted with a Mitsubishi Electric Ducted PEA71 Heat Pump. This allowed the transfer of up to 3.35 kilowatts of heat while consuming only 1 kW of electrical energy. Not only this, the unit’s key concealment in the ceiling cavity went a long way to aiding the team’s interior design appeal. Coupled with another integral component to the house, a Mitsubishi Electric Lossnay Fresh Air (Energy Recovery Systems) LGH-15RX5-E , the house took 1st place outright in the Engineering contest. This system recovers energy from the air it expels, and transfers it directly to the fresh air it brings in, leaving the temperature and humidity in the house relatively stable. This lessens the need for additional heating from the heat pump.