And now there is an excel calculator.

heating cost calculator.xlsx

**if an error is spotted, let me know and i'll fix it

gregmcc:

 

No - Sorry not done in Excel

 

Some things you need to know to work it out

 

Cost of the gas per MJ of energy. Gas usage of the gas appliance as well as it's efficiency and it's rated output in KW and usage in MJ per hour, in my case:-

 

$175 for a 45kg gas bottle which has 2200MJ of energy (stated by the gas bottle supplier)

 

Heater is 5KW and efficiency of 73%, running on high setting this is 25MJ/hr of energy usage.

 

2200/25 (bottle MJ/usage per hour)=88hrs of run time per bottle

 

$175/88 (cost of bottle/run time per bottle)=$1.99 per hour for 5kw gas heater

 

 

 

For electric heating

 

for me my cost of electricity per KWH is $0.3088

 

for equivalent electric heating (assuming a standard resistive heater - such as a fan heater or similar = 100% efficient)

 

=0.3088x5 (cost per KWH x 5kw)=$1.54 per hour

 

For heat pump,

 

Heat pumps vary between 400%-800% efficiency this varies depending on make and model. I have taken a 5.1KW heating capacity heat pump and an efficiency of 500%

 

=5.1/5 (heating capacity/efficiency)=1.02KWH

 

Power usage=1.02x0.3088 (power usage x cost per KWH)=$0.32 per hour.

 

 

 

keep in mind these things :-

 

Gas fireplaces have a built in fan to circulate the heated air - the power usage for this has not been included.

 

Same for the electric fan heater - fan power usage not included

 

Heat pump power usage varies as it reaches it's set point temp it ramps down the power usage to hit the target before switching off, and actual power usage varies between makes and models for the same heating output.

 

 

 

so for us, electric fan heater is 5 times the price of a heat pump, 6 times the cost for a gas fireplace using bottled gas, the gas fireplace is over 20 years old and in the calculations it was assumed to be working as new based on manufactures specifications, so there could be more losses/gas usage due to age related inefficiencies. 

 

 

 

 

 

 

 

 

 

 

 

Thanks for the sheet 

I have four heat pumps and a massive Escea 2m wide dual-sided gas fire. I also have a Rhinnai gas hot water. Where I am, this is street-supplied.  So yes, you pay 2 base fees. Also in many cases you also can only use the nominated gas supplier and the rate they charge. I would check on local forums as they will have people on the plan (I am in Faringdon in Rolleston for example and we have to be Genesis).

Is the gas getting more and more expensive? Yes. Is it worth it? For me, yes.

The instant heat, no lugging firewood, and the visual fire from the Escea dual-sided are bloody awesome. The instant hot water that never runs out is superb. 

If building again today, would I do it? Maybe, probably not to future-proof. Would i not buy a house over it. Maybe but if everything else is great yes I would. YMMV.

Quinny:

 

I have four heat pumps and a massive Escea 2m wide dual-sided gas fire. I also have a Rhinnai gas hot water. Where I am, this is street-supplied.  So yes, you pay 2 base fees. Also in many cases you also can only use the nominated gas supplier and the rate they charge. I would check on local forums as they will have people on the plan (I am in Faringdon in Rolleston for example and we have to be Genesis).

 

Is the gas getting more and more expensive? Yes. Is it worth it? For me, yes.

 

The instant heat, no lugging firewood, and the visual fire from the Escea dual-sided are bloody awesome. The instant hot water that never runs out is superb. 

 

If building again today, would I do it? Maybe, probably not to future-proof. Would i not buy a house over it. Maybe but if everything else is great yes I would. YMMV.

 

 

 

You just can’t beat gas heating or water , such a nicer heat than heatpumps. The gas hot water never runs out . Worth the base fees , 100 % agree

Quinny:

 

I have four heat pumps and a massive Escea 2m wide dual-sided gas fire. I also have a Rhinnai gas hot water. Where I am, this is street-supplied.  So yes, you pay 2 base fees. Also in many cases you also can only use the nominated gas supplier and the rate they charge. I would check on local forums as they will have people on the plan (I am in Faringdon in Rolleston for example and we have to be Genesis).

 

Is the gas getting more and more expensive? Yes. Is it worth it? For me, yes.

 

The instant heat, no lugging firewood, and the visual fire from the Escea dual-sided are bloody awesome. The instant hot water that never runs out is superb. 

 

If building again today, would I do it? Maybe, probably not to future-proof. Would i not buy a house over it. Maybe but if everything else is great yes I would. YMMV.

 

 

 

yeah, I agree with the ‘if everything else is great’ part. Thanks for the input.

JayADee:

 

Hi,

 

‘We’re thinking of selling our house and buying smaller both house and lot size.

 

A 92m2 house we’re looking at has piped gas from the street and a gas fireplace installed as a heat source.

 

What kind of costs are you looking at for running that as compared to say a heat pump? My present house has heat pumps and a modern wood burner.

 

Thanks!

 

We have hit the point now, where it makes sense to forgo a natural gas connection on new home builds, and as appliances come to end of life, it makes sense to move away from gas.

A such we risk a death spiral, where the gas networks give up on trying to attract new customers, and instead focus on miking their existing customers for all they can for the last say 20 year lifespan of their network. Even beyond the milking, every time a customer leaves the fixed costs need to be spread over a smaller pool of customers, driving per customer cost up, and hence making disconnection from gas more attractive. Furthering the spiral.

In general, while I consider gas undesirable at this point, I wouldn't write off a prospective house because if it. Gas works (and works well), it is just getting a bit expensive... No issue planning to swap out in a decade of so when appliances reach the end of their service life.

Quinny:

 

I have four heat pumps and a massive Escea 2m wide dual-sided gas fire. I also have a Rhinnai gas hot water. Where I am, this is street-supplied.  So yes, you pay 2 base fees. Also in many cases you also can only use the nominated gas supplier and the rate they charge. I would check on local forums as they will have people on the plan (I am in Faringdon in Rolleston for example and we have to be Genesis).

 

Is the gas getting more and more expensive? Yes. Is it worth it? For me, yes.

 

The instant heat, no lugging firewood, and the visual fire from the Escea dual-sided are bloody awesome. The instant hot water that never runs out is superb. 

 

If building again today, would I do it? Maybe, probably not to future-proof. Would i not buy a house over it. Maybe but if everything else is great yes I would. YMMV.

 

LPG is a blend of propane and butane (heavier than air, and can be liquified at easy to deal with pressures for easy transport).

Natural Gas is mostly methane (lighter than air, and requires cryogenic temperatures to liquify).

Different cost structures & hazards.

Scott3:

 

In general, while I consider gas undesirable at this point, I wouldn't write off a prospective house because if it. Gas works (and works well), it is just getting a bit expensive... No issue planning to swap out in a decade of so when appliances reach the end of their service life.

 

Or sooner. We have a property in Auckland where we are getting a new switchboard installed. As part of this install we are getting a prewire done to enable replacement of the near EOL gas hob with induction and eventual replacement of the 5 year old gas hot water cylinder. The timing of the replacements isn't decided but we are planning ahead so we can easily pull trigger on replacements.

Handle9:

 

Scott3:

 

In general, while I consider gas undesirable at this point, I wouldn't write off a prospective house because if it. Gas works (and works well), it is just getting a bit expensive... No issue planning to swap out in a decade of so when appliances reach the end of their service life.

 

 

Or sooner. We have a property in Auckland where we are getting a new switchboard installed. As part of this install we are getting a prewire done to enable replacement of the near EOL gas hob with induction and eventual replacement of the 5 year old gas hot water cylinder. The timing of the replacements isn't decided but we are planning ahead so we can easily pull trigger on replacements.

 

We are in a similar position with mains gas for hot water and the hob. I would like to convert to electric sooner rather than later. A friend of ours (all electric) went on a power crusade trying to minimise their bill and asked about our usage. Given we are a couple in a house, with mains gas we could reduce our energy consumption by 25% but only save 15% in dollar terms. 

We could away for a month and our bill is still exactly $100 which is made up of the two line charges (electric $46.50 @ $1.50 per day and $44.10 @ $1.47 per day). So I don't really bother trying to save power. 

I've just been doing some calculations on piped vs bottled gas, and it seems as though with our historical usage we would save about 25% (~$260) per year from switching to bottles. 

This would also give us the added benefit of immediate savings from progressive switching of appliances from gas to electric as and when we can afford it. 

Now the question is whether there are any hidden flaws to this plan, and to find out the cost of having a gas fitter do the initial bottle install and disconnection from the Vector supply. 

You’d need to check if your appliances need conversion from natural gas to LPG and factor that into your calculations. 

Handle9:

 

You’d need to check if your appliances need conversion from natural gas to LPG and factor that into your calculations. 

 

Have done this for a gas hob it’s just a few dollars in parts for the gas jets and 15min labour. No idea about other kinds of appliances. 

Our house came with an old underfloor diesel furnace and underfloor ducts. A hallway thermostat started and stopped it and every room including two bathrooms and office has an outlet grille with a baffle. Bloody brilliant as it warms the whole house very quickly with a nice dry warmth and the filtered air from the basement pushes the room air out of the house through the draughty joinery. 
But…

The 600L diesel tank required filling twice a year at about $1100 a pop and at any one time we would really only need to warm 1 or 2 rooms not eight. 

So have retired the central heating and installed a massive split heat pump in the kitchen/lounge/dining space. Over winter the power bills appear to have gone up about $100 a month so a saving of roughly $1600 pa. The effect is almost as fast as the central heating. This heating is easier to automate as has home automation interface. (I had Shelly 1L on the central heating thermostat). The installation was $1150 IIRC. Easy money for the installer as this one was as straight forward as they come. The HP unit itself cost very little as an able to purchase through a staff deal. Don’t use it much for cooling in summer as plenty of French doors and verandas make the house pleasant and shaded from the high sun angles. 

Downsides: Only heating one end of the house. The warmth is not as soft and calm and it doesn’t refresh the air. The indoor unit looks a bit ugly up on the wall.

Overall it’s a significant cost and emission saving. Probably should get a small split unit for our bedroom at the opposite end of the house. 

gregmcc:

 

 

 

For heat pump,

 

Heat pumps vary between 400%-800% efficiency this varies depending on make and model. I have taken a 5.1KW heating capacity heat pump and an efficiency of 500%

 

=5.1/5 (heating capacity/efficiency)=1.02KWH

 

Power usage=1.02x0.3088 (power usage x cost per KWH)=$0.32 per hour.

 

 

 

Heat pump power usage varies as it reaches it's set point temp it ramps down the power usage to hit the target before switching off, and actual power usage varies between makes and models for the same heating output.

 

cop for heat pumps is typically 3-4.  tho some are higher. also that figure is best case, often at slow speed/output. so when its heating a house up, its often at lower cop so running costs are a tad higher. also if its a multi split, it can drop down to 1-2 cop in bad cases.

the other factor is how we use them. often kiwi homes are to poorly insulated to run them constantly, maintaining temp. so we use them in the less efficient way of heating a home back up (despite nz media pretending otherwise).

so your case shown here is the best case possible rather than realistic usage.

i looked into this for work. we use a larger sized (25kw) domestic califont for heating water.

compared to a heat pump or diesel unit, they are cheap units. however bottled gas, when used on higher out put units, has limitations. the hot water output declines with outdoor temps. not only cold air effecting the unit it self, but also the gas supply. this is where mains supply may well be better. or do a dual parallel bottle connection instead. but council requires consent for more then 90kg of gas on site. diesels all require consent.

jamesrt:

 

gregmcc:

 

I done some calculations a little while back on bottled gas(fixed gas fireplace) vs plug in electric heater vs heatpump

 

 

@gregmcc; any chance that was an Excel (or similar) spreadsheet that you've still got available to share?

 

We're starting a new-build for the Kāpiti Coast - in the design process currently.  My wife is very keen on a "feature" gas fire; I'm less keen on the expense and need evidence to support my argument...

 

 

 

Are you having gas for any other appliances? I'd recommend going all electric in a new build and plan for solar PV & battery either now or later. This could be just having conduits or draw wires to the right places to pull cables later.

If you have to have a gas fire, I'd recommend running it on gas bottle then your not beholden to the gas company. The government will do very little to stop price increases. `

There never a cheaper time to do all this than when you're building.