Beacon

Overall energy savings

In their first year of living in the Waitakere NOW Home®, the tenants used 7400 kWh per year or 33% less than a comparable 4 person household with school age children.  This was also 45% less than the tenants’ energy use in the house they occupied over the year prior to moving into the Waitakere NOW Home®.  The tenants were delighted with their lower energy bills which they noticed very early on.

In the second year, energy use rose to 8500 kWh over the year.  While this is an increase in what was achieved in the first year, it is still 25% less than a comparable 4 person household with school age children. 

Analysis shows that the tenants have changed the way they use the house in response to its warmer, drier environment and lower energy bills. 

• The house was increasingly used as a home office, reflecting that it was a pleasant, warm and quiet place to work.  The high running costs of computers/servers have been offset by lower power bills.
• The tenants have invested in more appliances.  Lower energy bills mean more money in the pocket.
• Hot water use increased in the second year.

The lower running cost has buffered the household against rising energy prices, and continued to provide more disposable income. The tenants still saved energy compared to similar households, while maintaining a high degree of comfort and expanding their use of the house.

Keeping the house warm

Designed to only need additional space heating on 10 days per year, the Waitakere NOW Home® has performed better with additional heating only required on two days per year.  There is no inbuilt heating – the tenants have used a small fan heater when necessary.

The living room had an average winter temperature of 21.6°C and the bedrooms had an average night-time winter temperatures of 17.4°C -17.7°C. The winter mean temperatures all exceeded World Health Organisation minimum of 18°C for living areas and 16°C for bedrooms (compared to 30% of New Zealand homes which regularly don’t meet these standards). 

Free energy

In Year 1 the solar water heater provided more than half (55%) of hot water needs. That’s equivalent to a saving of 1620kWh (compared to similar houses in the area) or about $275 on water heating alone. 

In Year 2 the solar water heater provided 45% of hot water needs, 1880 kWh in total.  Although the solar water heater provided more kWh in total, the increased hot water use by the household means that a lower proportion was provided by solar. 

Surprising energy guzzlers

The energy use of appliances was more intensively monitored in the second year to see what part they play in household energy use.  Appliance use was high; on average the TV was on 40-45 hours per week, the stereo 30 hours per week and the home computer/s 50 hours per week.

The home office, with several computers and a server, was a high energy user, forming 10% (847 kWh) of total energy use.   When calculating the cost of a home office, it is important not to underestimate the associated energy costs.

Also of interest for many households is the high energy use of the large screen TV which used 5% (391 kWh) of total energy use, more than the oven and fridge.