The Rotorua NOW Home

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The Rotorua NOW Home was Beacon’s second live research project. The Waitakere NOW Home established that it is possible to build and design a home that performs well using basic principles and materials available today.  The principles were developed by a team of experts in sustainable building and the house built to those specifications.  The Rotorua NOW Home project took the next step.

The house was our first collaboration with Housing New Zealand Corporation (now Kainga Ora).  It designed with the advice of our building experts to   meet the requirements of Housing New Zealand.  Housing New Zealand Corporation owns the land on which the house was built and on completion, the home became part of Housing New Zealand’s rental stock.  

The performance and comfort of the home was remotely monitored for   one year while a family lived in it.  Data was collected on energy use,  water use, rainwater collection, temperature, indoor air quality,  humidity and moisture levels.

Working closely with the homeowner and monitoring the resulting home’s performance have taught us much about the extent to which we can adapt or compromise the principles developed in the Waitakere NOW Home.

Simple principles of good building

By using simple, proven designs and technologies in combination, the Rotorua NOW Home addresses the whole house - from energy efficiency to water to the indoor environment, and even to waste.

Its simple features include:

  • A design which faces the north with lots of windows on the northern side
  • Wide eaves to let the winter sun in but keep the summer sun out
  • A concrete floor which absorbs heat from the sun and releases it when the air is cold
  • High levels of ceiling, wall and floor insulation, much higher than in the Building Code
  • Double glazed windows to keep the heat in and the noise out
  • Solar water heating
  • Water efficient taps, toilet and appliances
  • A rainwater tank to collect and reuse rain
  • Ventilation of moisture in the kitchen and bathrooms
  • Passive ventilation to keep down moisture and avoid overheating
  • Good natural light in all rooms combined with efficient light fittings and bulbs

The results

The living areas reached WHO-recommended minimum temperatures during the day and evening.  However, the bedrooms were too cold, especially over-night. Cold bedroom temperatures contributed to higher-than-recommended relative humidity levels

A number of factors contributed to this poorer-than-expected performance

  • A heat pump, recommended by the building design experts, was not installed - this would have taken heat from the living areas to the bedrooms
  • The pellet fire was moved from its optimal site to a less effective site, and the family weren’t given help in how to use a pellet fire effectively
  • The concrete floor was covered in rugs because its poor finish was unsightly and the family were concerned about their elderly member falling on the hard surface.  This reduced its ability to absorb and release the sun’s warmth.

The family used only 6800 kWh per year, lower than the Waitakere NOW Home.

The solar hot water cylinder was a poor performer, needing considerable electrical boosting.  In fact, boosting formed 41% of the home’s electricity usage.

While the Rotorua NOW Home used slightly more water per year than the Waitakere NOW Home, 74% (148 litres) of the water came from the tank. This compares to the Waitakere tank which supplied 47%-52% of the home’s water needs.  This may be because, although the Waitakere NOW Home had a much larger tank, it did not have an automatic switch between tank and council supply.

Read the Rotorua NOW Home case study for more details