Save Energy, Save Money, Save the Planet

Energy bills seem to be designed to be difficult to understand. That way, we just pay the bill and don’t ask too many questions! Understanding our energy bills are the first step to reducing them, and ringing your provider to ask them to talk you through it can be helpful. For New Zealand, Canstar Blue has prepared a resource to understanding energy tariffs and Powerswitch helps Kiwis find the energy provider that will be most cost effective for their household.

Below is a diagram from EECA that offers some useful first steps to reducing energy use.

Infographic with tips on saving energy in your home

Approximately a third of the energy a household uses is on heating (and/or cooling). To reduce your need to heat or cool your home, this post about Passive Solar Design and this post about making warm and dry homes can help.

Another third of our energy goes to providing us with hot water. To reduce this component of our energy use, check out Cool Ways To Save On Hot Water.

The final third of our energy use is associated with lighting and appliances.

The Lighting section of the EECA website offers great support for all things relating to lighting, including choosing the right bulbs, looking at down lights, and making the most of natural light.

EECA also have a brilliant section on Appliances, which looks at how to effectively use different appliances, and how to learn about how energy efficient they are.

Each programmable appliance (dishwasher, microwave, computer, etc) or appliance that uses a remote control (TV, stereo, etc) uses approximately $20 NZD a year in standby mode. That is for each appliance. Conducting a simple appliance audit (i.e. walk around your home and note how many electrical appliances you have, and also how many of those are on standby) can help identify sources of electricity inefficiency and wastage.

Tip: Stand up and walk around to do the audit, rather than sitting in one place and trying to do it from memory – it will be much more accurate this way!

And finally, if you want to learn how to monitor the electricity consumption of different appliances or your home in general, check out this video:

Remember: increasing energy efficiency and reducing waste is often about taking a lot of small steps, rather than a few larger ones. But the small steps accumulate into big effects!




Your Home: Cold and Damp, or Warm and Dry?

As someone who was raised in Germany and now lives in New Zealand, I’ve got to say I love this videoclip!

Most of New Zealand’s houses have poor thermal performance. In winter, most of them are cold and damp. The remainder are warm but expensive to run. Ian Mayes says the problem is most Kiwis have not lived in warm, dry homes; poor quality homes have been normalised. It is so common, that  parts of the Census is dedicated to asking whether your home is cold and whether these is mould growing in it.

Thermo-Hygrometer: Modell HM 16We should all have thermo hygrometers in our homes. If everyone had one, there would be riots as people realise they are paying so much for cold, damp, poorly performing homes.

Ian Mayes, 2018

Making our homes warmer

Our homes can be made warmer by heating them well and reducing heat loss.


There are different ways we can heat out homes, and EECA has created a great resource to compare the options, depending on the size and use of the space you want to heat.

Reducing Heat Loss

Tips on insulating and reducing heat loss can be found in this blog post but here’s a little bit of extra info about my favourite topic – windows!

A single pane of glass only has an R-value of between 0.15 and 0.19. Standard double glazing is around R 0.26 and the fanciest double glazing might reach R 0.6.

Because even the best double glazed windows still have low insulating abilities, curtaining is very important.

The 4 rules for good curtaining are:

  • Cover ALL glass. Windows. Doors. Funny glazed spots. The lot.
  • Always 2+ layers. It is the air around and between layers that insulates, rather than the material itself. A single layer doesn’t trap nearly as much heat as a double layer.
  • Energy saving curtains should close off airflow over the window glass
    Image from

    Stop reverse convection currents. By having curtains touching the floor, or  pelmets, or both!

  • Good behaviour. Close curtains in the afternoon, to stop daytime heat escaping. Open curtains in the morning to allow heat in during the day.

Making our homes drier

Ventilation and moisture control can help us make homes drier.

Note: Ventilation is different to draughts in that the former is a chosen air exchange, while draughts are uncontrolled air exchanges and heat leakages.

We want less moisture in our homes because it makes them healthier and less prone to mould. Good ventilation combined with other moisture control practices can reduce relative humidity.

Once again, EECA have created a great resource for tackling dampness and reducing indoor moisture, which can be found here:


Future Living – Reduce your Energy Bill and Live Better

This article will be most helpful for people living in Aotearoa New Zealand, or areas with similar climatic conditions.

If you live in Aotearoa New Zealand, you can have an Eco Design Advisor come to your home and carry out a free and impartial Home Performance Assessment. It supports people reduce their resource use (energy, water and waste) and improve their home’s performance.

Bigger Picture

In Aotearoa New Zealand, the majority of homes perform to a very poor standard. They are cold, damp, expensive to run, and making us sick. Each year there are 1600 deaths caused or contributed to by poor housing conditions.

According to the World Health Organisation, the following temperatures lead to health implications:

  • Less than 16oC affects respiratory system
  • Less than 12oC affects cardiovascular system

(These values are for healthy adults. Children, elderly and people with illness or disabilities require at least 2 degrees warmer than these values.)

Living areas should not fall below 18 degrees and bedrooms should not fall below 16 degrees. Yet in New Zealand, 17.9% of living rooms are colder than 18 degrees during winter months (despite active heating), and 13.6% of bedrooms are colder than 12 degrees. In addition, 55% of our homes have visible mould.

This is making people sick, but we can do a lot to avoid it.

For example, it has been calculated that for every $1 you invest into insulating your home, you save $6-10 through direct cost savings (e.g. power bill) and indirect savings (e.g. lower medical bills, better school attendance and education, etc.).

When designing or retrofitting a home, it is important to consider 3 factors:


If you try to cut on one, you will end up cutting on the others as well. We spend 55% of our lives in our home, so it is important to make sure we make it good.

energy use

Our energy use is divided roughly equally into

  • Spatial heating
  • Lights and appliances
  • Water heating

If we can reduce the cost involved in any of these, we simultaneously reduce our energy bill and impact on the planet.


Lowering energy needed for spatial heating

There are two ways to go about reducing energy needs for heating:

  1. Heat the home more efficiently,
  2. Make sure heat is not lost

Heat the home efficiently

There are many different ways to heat homes. Below are some common home-heating methods ranked according to cost effectiveness. Cost effectiveness refers to how much warmth you get for how much money it costs to run.


  1. Heat pump (converts 1kW of electricity into 5kW of heat)
  2. Wood burners (they emit a lot of heat and are relatively cheap to fuel. They are even cheaper to run if you collect some of the fuel yourself)
  3. Gas heaters (flued!)
  4. Electric heaters (ones you plug into the wall, such as fan heaters, oil column, panel/ecopanel, etc.)
  5. XXX Unflued gas heaters XXX – these should be avoided, as they burn oxygen, release toxic gases (including carbon monoxide) and emit moisture (which makes homes damper). They have been banned in most Western countries, though unfortunately not yet in New Zealand.


Make sure heat is not lost – Insulation

Insulation slows down the movement of heat. Good materials to use for insulating have low conductivity and air pockets (as still air is highly insulating). R values are used to reflect the thermal resistance of different materials. Thermal resistance is the ability of a material to keep cold things cold and hot things hot.

Heat loss is motivated by temperature differentials. The larger the difference in heat, the faster the heat will move. In an uninsulated house, heat can be expected to be lost in roughly the following ways:energy-use1.png

Insulating different places (e.g. ceiling, underfloor, etc.), reduces the overall heat loss speed. However, it is important to think about the whole thermal envelope of the house. It does not make sense to just insulate one area of the house as the heat will then just escape somewhere else. It can be likened to being naked in the cold: it helps if you put on a jacket, but to get truly warm you will also need trousers, socks, hat, etc. 3 jackets but no trousers/socks/hat is not as useful as one of each.

Below are R values according to the Building Code and as recommended by Ian Mayes:


Make sure heat is not lost – Curtaining

Curtaining windows is important because windows allow a lot of heat loss. There are 4 rules to good curtaining:

  1. Curtain all glass (or cover it in some way if it is not possible to put a curtain on)
  2. Have 2 (or more) layers
  3. Stop convection currents through pelmets and having curtains to the floor
  4. Good curtain behaviour – close curtains before heat is lost, around 4pm.

The diagram below illustrates the difference between a well and poorly performing curtain:energy use

Lowering energy needs for lights and appliances

The way we use appliances majorly affects their energy performance, and the average household can save several hundred dollars each year by taking the following steps:

  • Switching off appliances at the wall. Appliances that use a remote or are programmable each use $20 of electricity a year by being in standby mode (this includes TVs, DVD players, internet modems, game consoles, microwaves, dishwashers, washing machines, and more).
    Image result for power strip new zealand

    Each appliance that gets switched off at the wall when not in use will save $20 of electricity. TIP: Organise the appliances you want to keep on vs the ones you would like to switch off using a multiplug/powerstrip. 

  • Switch to LED lightbulbs. These are more expensive to buy, but they pay for themselves within the first year and lead to hundreds of dollars worth of savings in their lifetime. TIP: You don’t have to replace all bulbs in one go. Switch the bulbs you use most often first of all(kitchen and living room, then bedroom). You might want to check out this tool to calculate your savings when you replace different light bulbs, created by the EECA.

Lowering energy needs for hot water

  • If you have a hot water cylinder, insulate it with a cylinder jacket.
  • Insulate the hot water pipes leading out of the hot water cylinder as well.
  • Reduce the amount of water used in showers (as showers use the bulk of a household’s hot water). This can be done by:
    • Image result for egg timerShortening shower length. Depending on how long your household currently showers for, and how long shower time is reduced by, there is potential for hot water usage to halve (or more) by shortening shower time. Each minute added to a person’s daily shower adds up to about $70/yr. TIP: Put a 3 or 4 timer in the shower to help keep track of shower lengths. Even switching off the water while lathering and/or shaving helps reduce hot water usage.
    • Reducing water flow. You can check the flow rate of your shower head. If it is greater than 9 litres per minute, it may be good to reduce the flow rate. The video below shows how to do this with a flow restrictor, or you may wish to replace the showerhead to a more water-efficient one.

The Energywise website has many useful resources and tips to making your home energy efficient:

[All statistics from BRANZ and EECA.]

Week 16 – Insulation

Winter is coming to New Zealand. Our house is old and very poorly insulated, and I have wanted to make it more energy-efficient since we moved here a year ago. So for week 16’s action I decided to learn a bit more about insulation, including the positive and negative environmental impacts.

What I learned

Among others, I read the article ‘Insulating Materials: Environmental Comparisons’ : I found it offered a good comparison for different insulating materials.

I learned many things, including that certain insulating materials contribute to ozone-depletion (as they contains CFC’s) and that most kinds of insulating materials contain recycled materials (this percentage can vary from 5% to 100%). In terms of embodied energy, cellulose insulation and then wool insulation are the lowest, but both of these have low insulating power per metre, compared with some of the less sustainably sourced materials.


We installed insulation in our house: the underfloor insulation is wool, and the roof insulation is wool mixed with plastic from recycled bottles. It was placed thickly enough so that it is suitably insulating, and we already feel the difference. It was more expensive than some of the other alternatives, but I am happy that is is an environmentally-considerate product.

I also added the company that installed it to the mailing list of the Sustainable Business Network, so that when there are events they can come and network and promote their work and sustainable products to others.