Beacon

NZ Housing Foundation HomeSmart Home

The HomeSmart Home featured a grid-linked solar power system capable of producing in excess of 2100kWh per year. The system is made up of three main components: solar modules, inverter and array frame.  The solar modules comprise eight Sharp 175W 24V panels with a total surface area of 10.4m². The panels, mounted at an angle of 28° facing north-west-west, are fastened onto the roof using a Conergy solar array frame.  The DC power produced by the solar panels is fed into a SMA Sunny Boy 1700 inverter which converts the energy to 240V AC. The resulting energy is connected to the switchboard in the house and then either used to meet the power needs of the home, or fed to the grid.

The photovoltaic system generated nearly a third of the electricity used in the home, about 2000kWh per year.  This amount was about what was expected based on Auckland’s predicted solar radiation, indicating that the system was optimally installed. The occupants directly used 1000kWh, while the rest was returned to the grid. 

The homeowners appreciated the significant cost savings and noted the house was very cheap to run. Compared to an average house in Auckland, the savings could have been as much as $1625 per year from the energy efficiency and generation measures.

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House 1, Papakowhai Renovations

In House 1, an old wood burner was replaced by a new low emission pellet burner and combined with a heat transfer system. As a result average winter temperatures in the family room rose by 1.1°C, and in the main bedroom by 1.5°C. 

The warmer living room temperatures can be attributed to the more efficient pellet burner with heavy ceiling and under-floor insulation helping to retain the heat.  The homeowners report that they found the pellet burner to be extraordinarily efficient, convenient, ‘guilt free’ and safe, and had increased their heating as a result, running it from 4 pm to 10.30 pm in winter.

The heat transfer system effectively moved heat from the central pellet burner to the bedrooms.  Beacon recommends an overnight minimum temperature of 16°C. 

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House 10, Papakowhai Renovations

In House 10 an old wood burner was replaced by a new wood burner which was compliant with the National Environmental Standards for Air Quality.  You can find a list of compliant wood burners at http://www.mfe.govt.nz/laws/standards/woodburners/index.html A wetback was also installed to boost the solar water heating system.  The results showed that average winter temperatures in the family room rose by 1.4°C, and in the main bedroom by 2°C.  There was a significant improvement in the proportion of time the family room and main bedroom were at a healthy temperature. 

The homeowners noticed that warmer temperatures in the house during winter, especially in the morning.  In addition they found the cost savings from reduced energy consumption a very real benefit.  They attributed the savings to the solar water heating and wetback on the installed wood-burner which provided almost all the hot water needed between May and September. 

Although the wood burner was very efficient, it couldn’t get heat down to the other end of the house, so the family ran oil heaters as supplementary heating in the bedrooms.  They plan to install a heat transfer system to maximise heating from the wood burner in the future.

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Waitakere NOW Home®

 The Waitakere NOW Home® was designed for passive solar heating, making the most of the sun’s warmth, and retaining that heat.   The house is oriented north, with both living areas, the dining area and one bedroom sited on the northern face of the house.  Large windows and doors admit the maximum amount of sunlight during winter while overhanging eaves provide summer shade.

In Auckland’s warmer climate, the Waitakere NOW Home® has no in-built space heating system.  Together with extra insulation, the passive solar heating has provided an average winter temperature of 21.6°C in the living areas, and an average night-time winter temperature of 17.4°C -17.7°C in the bedrooms.  Additional heating was only required on two days per year in the form of a small fan heater.

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