Why has my power bill skyrocketed?



Over the years I have visited 1,000s of Kiwi homes for energy assessments and to provide advice on keeping people healthy, warm and reducing energy consumption.

Got a question on how to lower your energy use at home or work? Drop us an email at info@ecogeekco.co.nz

Recently we had a customer whose power bill for the month hit $700.  They suspected the heat pump to be the cause of this, but given the efficiency of modern heat pumps, it could be something else chewing through the power.

Here's our guide to help keep you on top of your power bill this winter.


1. Check the temperature of your hot water

Use a simple thermometer to test your water temperature at your taps

Use a simple thermometer to test your water temperature at your taps


If it’s over 55 degrees at the tap, then you probably need to reduce the temperature.

Your hot water cylinder should be set to 60 degree (this temperature prevents the growth of legionella bacteria), this water is then ‘tempered’ down to 55 degrees by a cold water mixing valve at the cylinder.

Sometimes plumbers set the cylinders at higher temperatures to avoid any callbacks, but this means you often end up wasting energy. 60 degrees is often the correct temperature for the hot water cylinder. When you are heating over 60 degrees, there is a good chance you are wasting energy and money.

Turning hot water cylinders down can be done by any plumber, handy person or electrician. They may need to adjust your ‘tempering’ valve to compensate for the slightly lower water temperature. It’s well worth looking into this as water can account for as much as 35% of all your energy use.  



2. Keep your heat pump clean and mean

Depending on the age of the heat pump, it should be pretty energy efficient compared to most other types of heating. However, they are only as good as the amount of heat they can recover from the outside air.

Here's some tips to make them work their best (and most energy efficiently).

  1. Have you cleaned your heatpump’s filter? If you’re having to put up the temperature on the heat pump and feel like it's not really delivering the heat like it use to, check your filters to make sure they are not blocked.  See your manual for instructions of how to clean your air filter. Often it just requires removing it and using a vacuum to remove the dust.
  2. Check it’s not on Auto mode. Often if your heat pump appears to be blasting cool air after heating it could mean the mode has been switched to ‘Auto’. This means the heat pump will be cycling between heating and cooling to maintain a temperature. This uses lots of energy and wastes your heat. Make sure the heat pump is on the heat mode (often indicated by a sun symbol). Also make sure your fan is not cranked all the way up for too long. This will cause it to use even more power (unless you want a good blast to warm the place up).
  3. Is your outdoor heatpump unit positioned in a shady or cold spot? If so, it's likely it's not working as efficiently as it could be. It needs access to sunshine and warmth, but unfortunately they are usually positioned for minimal visual disturbance (which is often on the south, damp side of the house!).

    If it’s hidden around the back of a house near tall cliffs and banks it will be less efficient as cold air drops down the cliff/bank, meaning there is less air available for the heatpump to pull heat from. One option could be to get your heatpump moved to the sunny side of your house. There it will have access to warmer air. This will increase the efficiency. 


3. Do you have a sieve in your ceiling? 


Have you got downlights installed in your ceiling? A single downlight in a 10m² of ceiling could negate your ceiling installation value by up to 80%!

Downlights cause rapid heat loss because they heat up, and draw the warm air up into the cold air in the roof cavity.  Due to the heat that regular light bulbs can create, you can’t insulate over a downlight either as it is a fire risk. Your best option? Look to replace with encased LED lights that can be insulated over.


4. Is your heater the right one for the job?

Often a visit to buy a heater, leads Kiwi’s to walking out the shop door with a cheap non-efficient plug in heater like an oil column or convector heater.

What’s a convector heater? Well it’s a heater that often has a simple coil inside it to heat the air. The warm air then rises off the top of the heater. These can heat a room very fast. However, warm air rises, it’s a thermodynamic called ‘heat stratification’. This means your expensive heat is constantly rising off the top of the heater to the ceiling above. That’s no good for you, or your wallet, unless you happen to live on the ceiling.

The other issue is that these cheap, readily available heaters often do not have sensitive thermostats. This means they just run on full bore regardless of whether they have meet the temperature requirements of the room or not.

Our advice is to source a heater with ‘radiant’ properties.

We highly recommend the Atlantic Tatou heater for its radiant heat and energy saving sensor. This means it doesn’t focus all its energy on heating the air. Instead it transmits heat directly from surface to surface (similar to a log fire or glowing heater). This means heat can stay at floor level for longer so you can heat a room with less energy. If you are looking to buy a heater, aim for a heater with a digital thermostat as this will give you a little more control.


5. Fill in the gaps in doors and windows

There are many cheap options for filling in the gaps in between doors and windows. From foam to v-strips - these should be available at your local hardware store.

If you’re keen to try out temporary double glazing, we also recommend DIY double glazing kits. I’ve used them at home and still have some up from three years ago. We’ve slowly replaced most of our windows with UPVC double glazing from Thermal Frame, but some of our doors and windows will stay single paned for a few years to come yet!


6. Running a dehumidifier?

If you’re running a dehumidifier, consider where the moisture is coming from in the first place and try to reduce this as much as possible. Wet air takes most energy to heat, and dehumidifiers use lots of energy as they have to be on all the time. If you run one, make sure the room temperature is above 18℃ as they cannot recover moisture from the air at low temperatures.

We do create moisture through our own breath, but other sources can include steam from cooking and from showers.  If you don’t have a good extractor fan in the kitchen and bathroom, think about investing in these. It also helps protect your house (possibly your biggest asset) from future mold and rot!

Using a clothing rack inside your house to dry your clothes can also be a huge source of moisture.

Often we talk to people who own dryers, but run a dehumidifier to dry their clothes inside their house instead.  If you have a dryer, we recommend using it. It costs a lot more to run a dehumidifier for the 8+ hours to draw out the moisture from your clothes, than the hour it might take in the dryer.  Just make sure your dryer is vented to the outside, otherwise you’ll just be introducing more moisture into your house.

If your house sits on piles on top of soil, a relatively cheap way to reduce moisture in your house is to install (or pay someone to install) a ground vapour barrier under your house. This stops the moisture from the soil escaping and entering your house via your underfloor.  It costs around $600 for an average house to have a grand vapour barrier installed.  Warning, you’ll need to clear out any junk in the underfloor space first though!


7. Monitor your energy use

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You can do this in a variety of ways - either by buying an energy monitor (we have one at home and it’s great), or if you have a smart meter installed, you could request half hourly data from your electricity supplier. Many suppliers provide a dashboard where you can view your usage hour by hour.  


8. Seals sealed?

Ovens and fridge seals can fail after a number of years of use. If you can tell they aren’t closing properly and air is escaping, this is costing you. Investigate getting these seals replaced.


9. Light it up with LEDs

The price of LEDs has decreased dramatically over the past years. If you can, we recommend replacing traditional and CFL lights for LED when it comes time to replace.

If you have lots of halogen downlights, collectively these will consume a LOT of power. Did you know that only 5% of the energy that goes into a halogen bulb is converted to light? The rest is wasted as heat that vanishes into the roof space. Think about replacing them now with IC Rated LED downlights.

So, go LED if you can, or limit the use of the halogens where they are not needed so much (hallways etc).

The cost savings will pay off in no time!


10. Watch for extra power suckers

Got a spare fridge or chest freezer running and not at capacity? Consider condensing the contents and switching off to save energy. 

If you have a light in your underfloor or attic, check to make sure they are turned off too. I speak from experience here, there is nothing like finding out after six months that the old incandescent light in your attic or underfloor has been chewing through 100w an hour (costing you around $110 over the six month in power – oops!).


11. Background ‘small power’

We all have lots of tech lying around the house, from DVD players to multiple TV’s and set top boxes. All this draws energy even on standby.

We suggest getting a simple multi board with individual switches. This enables you to switch off any DVD players or chargers etc that are not being used. 40 watts here, and 30 watts there does add up as these are often going 24/7. Every little does matter when you’re battling big bills.

Got a question on how to lower your energy use at home or work? Drop us an email at info@ecogeekco.co.nz


Eco Geek Co