Page 85 - Build 152

Figure 1: Summary of passive design features in Waiheke Community Library.
Meters were installed on the lighting, heating and power circuits, and the overall energy consumption in the rst year was around 51 kWh/m2. However, this was distorted by the many operational and commissioning issues that occurred while the systems were being tuned and the occu- pants learned to use the building. This also does not take account of the contribution from the PV system that supplies electricity closely to the demand pro le of the building.
Learnings identi ed further savings
Early lessons from the building indicate that there are further possibilities for reducing electricity use.
External lighting that remains switched on throughout the night contributes to a higher than expected energy use – about 10 kWh/m2/yr. While this could be switched o , the building has become a civic centre for Waiheke, and the lighting illuminates the public areas that surround the building.
Anecdotal evidence indicates that recom- mended arti cial lighting levels are too high where an even distribution of daylight is achieved. Similarly, the high thermal mass of the building and contribution of internal heat
gains in a highly insulated building indicate that winter internal heating temperature settings could be reduced.
High yield from photovoltaics
The PV panels are predicted to produce about 27,500 kWh/yr, based on Auckland weather data that underestimates solar radiation on Waiheke.
SolarCity, the installers, are monitoring the output and estimate that the system will exceed the predicted output by about 10%. The measured yield this year has exceeded – for the equivalent PV area – similar systems installed not only in Auckland but also in Pacific Islands such as Rarotonga and Funafuti.
Tweaking improves performance
As the control systems are tweaked and full monitoring continues, the performance of the building will improve. It already generates more electricity than it uses, resulting in excess yield in all but the winter months.
Further monitoring will reveal how close the likely increased output from the PVs and further energy savings could be to get the library to a zero-energy building.
Award winning
The building was the winner of the 2015 New Zealand Timber Awards, taking out the top award in the Commercial Architectural Excellence Category as well as the Overall Supreme Award.
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