Energy efficiency of the Waitakere NOW Home®

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Keeping the heat in

Passive solar heating

The Waitakere NOW Home® is 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 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.


Concrete floor in Waitakere living areaThermal mass

A 100mm thick concrete slab and footing acts as a heat sink to store the sun’s warmth and release it later in the day when the temperature drops.  To prevent heat loss into the colder surrounding ground and air, the slab is insulated underneath and around its edges.

The concrete floor has been left exposed in all the living areas to collect and store heat more effectively.

 

 

 

 

 


Photo: Deborah Dewhirst


Insulation

The Waitakere NOW Home® has higher levels of insulation than recommended in the New Zealand Building Code.  The ceiling insulation has an R value (a measure of its effectiveness) of R 4.6, considerably more than the Code minimum in 2005 of R1.9. The wall insulation has an R value of R2.8, nearly twice that of the Code minimum in 2005, R1.5.  These insulation values are also much higher than the new minimum standards introduced in 2008.


Preventing heat loss through windows

All glass in the house is double glazed, including the bi-fold doors. At night, heat loss through windows is prevented by using curtains with thermal linings.  The curtain rail is mounted close to the wall to minimise heat loss.


Using free energy

A solar water heating system was used in the Waitakere NOW Home® to use the free energy from the sun and significantly reduce energy costs.  

The solar water heater has collectors on the north facing roof, and an electric boosted mains pressure storage tank inside the house at ground level. 

Heat loss from the water pipes and cylinders was minimised with a carefully designed plumbing plan.  The hot water cylinder was situated inside and in the middle of the house, ensuring pipe runs to the most commonly used taps are as short as possible.


Using less energy

Space heating

Designed for Auckland’s warmer climate, the Waitakere NOW Home® has no in-built space heating system.  With extra insulation and passive solar heating it was designed to be warm enough that extra heating would only be needed on the 10 coldest days of the year.


Energy rating on Waitakere fridge

Appliances

Fisher & Paykel appliances with the best possible energy efficiency ratings available in 2005 were installed.  More efficient models are now on the market.

  • Dishwasher - 3 star energy rating with an energy consumption of 280 kWh per year.
  • Fridge - a 4 star energy rating with an energy consumption of 454 kWh per year.
  • Washing machine - a 2 star energy rating with an energy consumption of 57 kWh per year for cold washes, and 518 kWh per year for hot washes.


Lighting

Natural light was optimised with large windows in all rooms to reduce the need for artificial light between 9am-4pm all year round.  A Solatube skylight was installed in the kitchen to improve natural light. 

There are no recessed downlights as these create gaps in the ceiling insulation in a home.  CA-rated downlights allow ceiling insulation to be butted directly up to them to ensure effective insulation that meets the new Code requirements.  In the main living area with its cathedral ceiling, pendant lights have been used.  Compact fluorescent lightbulbs have been used where possible.


Home Energy Rating

The Waitakere NOW Home® was rated under the Home Energy Rating Scheme and received:

  • 8 stars out of a possible 10 for thermal envelope
  • 7 stars out of a possible 10 for hot water performance

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Waitakere NOW Home

Waitakere NOW Home®