By popular demand, I have been asked to make a page that helps people calculate
the financial numbers for replacing an older gas furnace with a new one. You
can play with the numbers to see how your situation would work out, as long
as your basic scenario is the same.
Financial Data
|
Comments:
|
| Gas rate |
$ |
|
/m3 |
Get from fuel bills |
| Electricity rate |
$ |
|
/kWh |
Get from power bills |
| Minimum Acceptable Rate of Return (MARR) |
|
|
% |
This is the rate of return you insist on for your
money (in our household, it's our mortgage rate, since any "extra" money
we have gets plopped in our open mortgage) |
| Time horizon |
|
|
years |
How long do you expect to be in the house? |
| Minimum difference to make a decision |
|
|
% |
Within this percentage, you would consider the decision
a wash financially (which is different from taking a bath financially). |
Data on Current Furnace
|
| Annual cost of gas |
$ |
|
/year |
From gas bills for the year. |
| Annual gas consumption |
|
|
m3/year |
From billed gas cost divided by rate |
| Percentage of gas used for heat |
|
|
% |
If you use gas only for heat, enter 100%. If you also
use gas for heating water, it will be closer to 75%. If you also use it
for a dryer or range, lower it a bit more. |
| Annual gas consumption for heat |
|
|
m3/year |
From previous calculation and gas heat percentage |
| Annual heating energy consumption |
|
|
MJ/year |
From gas consumption times 37.5 MJ/m3 |
| Annual furnace fan electricity consumption |
|
|
kWh/year |
Estimated from Dave's experience. |
| Annual GHG Emissions |
|
|
kg CO2e/year |
Based on 0.04968 kg CO2e/MJ energy from gas and 0.236
kg CO2e/kWh energy from electricity |
| Annual operating cost |
$ |
|
/year |
Calculated from above inputs |
| Assumed efficiency |
|
|
% |
Estimated based on furnace type and energy auditor
opinion. |
| Assumed life expectancy |
|
|
years |
Estimated based on Dave's experience. |
| Current age of furnace |
|
|
years |
Name plate data. |
| Remaining furnace life |
|
|
years |
Calculated from above inputs |
| Original cost of furnace |
$ |
|
|
Estimated based on furnace type. |
| Depreciated value of furnace now |
$ |
|
|
Based on straight line depreciation. |
Data on New Furnace
|
| Assumed efficiency |
|
|
% |
Based on quotes. |
| Annual heating energy consumption |
|
|
MJ/year |
From old heat consumption and the two efficiencies |
| Annual natural gas consumption |
|
|
m3/year |
Based on 37.5 MJ/m3 of gas |
| Annual furnace fan electricity consumption |
|
|
kWh/year |
Estimated from quotes. |
| Annual GHG Emissions |
|
|
kg CO2e/year |
Based on 0.04968 kg CO2e/MJ energy from gas and 0.236
kg CO2e/kWh energy from electricity |
| Annual operating cost |
$ |
|
/year |
Calculated from above inputs |
| Purchase price for new furnace (installed) |
$ |
|
|
From quotes. |
| Sales tax rate |
|
|
% |
In Ontario, GST applies, but not PST. |
| Sales tax |
$ |
|
|
Based on sales tax rate above |
| Total capital cost |
$ |
|
|
Adding the figures above |
| Energy audit cost |
$ |
|
|
Cost reduced by a $150 rebate available for energy
audits. |
| Manufacturer rebate |
$ |
|
|
From quote. |
| OPA rebate |
$ |
|
|
For variable speed ECM motor and programmable thermostat. |
| Utility rebate |
$ |
|
|
From Enbridge, for switching to high efficiency gas
and for the thermostat. |
| Federal rebate |
$ |
|
|
From NRCan, for high efficiency gas, based on the
energy audit. |
| Provincial rebate |
$ |
|
|
Matches the NRCan grant based on the audit. |
| Total rebates |
$ |
|
|
Adding the figures above |
| Total cost to the consumer |
$ |
|
|
Add capital cost and audit cost and subtract rebates |
| Expected recovery of furnace improvement in house
sale |
$ |
|
|
Realtor association estimates 50-80% of the heating
system improvement can be recovered in a subsequent house sale. This calculation
assumes 50% recovery. |
|
|
Results
|
| Payback without rebates |
|
|
years |
Calculated from the capital cost and the annual energy
savings. |
| Payback with rebates |
|
|
years |
Calculated from the total cost to the consumer and
the annual energy savings. |
| Life cycle cost of old furnace |
$ |
|
|
Total cost of owning and operating the old furnace,
assuming that if its expected life is shorter than our time horizon we
would replace it with the gas furnace when it dies. |
| Life cycle cost of new furnace |
$ |
|
|
Total cost of owning and operating the new furnace,
assuming we sell the house at the end of the time horizon and recover
50% of the added value. |
| GHG Emissions Savings |
|
|
kg CO2e/year |
Based on above calculations. |
Home