Living without electricity bills, and other ways to cut your energy costs

 

 

This is an electricity bill like none you will have ever seen before. It shows a credit of $224.28. Not a charge, a credit. In this article, we look at how this was achieved, how some heat pumps produce more energy than they use, and the holder of the ‘Greenest House in New Zealand’ title.

Johanna White generated more power than she could use, so she sold the surplus to her power company for $224.28.

 

Hence the credit on her power bill.  

 

 

As you can see from this photo of Johanna’s house, the roof is basically one big solar power panel, what they call a “peel-and-stick photovoltaic array”.

The thin-film photovoltaic laminates are adhered to a standing-seam metal roof.

Johanna’s house is part of a development in Vermont known as South Farm. Purpose-built with the goal using net-zero energy, or close to it, all the homes are built on a south-facing slope with two stories on the south and one story on the north. They are super-insulated and double-glazed and triple-glazed.

The homes have an innovation you may not have come across yet – heat pumps for heating and cooling their homes that draw heat from the ground during the winter and from the indoor air during the summer.

Unfortunately the technology is not quite there yet and the residents of South Farm have experienced some technical difficulties, but it is only a matter of time before the boffins perfect this “geothermal” technology, allowing us to tap into one of the world’s most potent energy sources – the heat energy absorbed and retained by the ground itself.

In the meantime, we’ll have to be content with air-to-air heat pumps.

All heat pumps work on the same principle, moving heat from one location to another with the help of a closed refrigerant loop, a compressor, and a heat exchanger. In this way they are able to draw heat from the air, earth, well water, or pond water. In summer, the process can be reversed so heat is pulled from the inside and dumped outside, cooling the inside of your home in exactly the same way as a refrigerator.
Because they move heat rather than generate heat, heat pumps can provide up to four times the amount of energy they use. Read more about them here.

 
Another innovation we’re excited about is the new breed of small wind-driven turbine generators.

 

Because these turbines apply the power directly to the blade tips, instead of using gears, they can start generating energy at just 5 – 7 km/h of wind speed, far less than traditional wind turbines, and there is little noise and vibration because there is practically no mechanical resistance and drag.

At the right site, a wind turbine can generate power more efficiently than solar panels – up to 1500KW, or around 20% of the average New Zealand household’s annual energy consumption. You can read more here.

 

We’ve looked at some of the greenest houses in the US, but how does New Zealand compare?

   

 

This passive solar house with its own water treatment plant in Papakura, just south of Auckland, is featured in the World’s Greenest Houses. 

The treatment plant goes well beyond the functionality of a typical septic tank, with tanks for both black and grey water, a worm composting system and soakage field.

  

 

 

 

 

“We were sceptical at first but would now have nothing else and highly recommend this system,” say the owners. “Maintenance is virtually zero and the system is easily managed by the owner. There are no smells and toilets flush like any other sewerage system.”
 

 

 

   

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