Does double glazing pay for itself?

Double glazing reduces heat loss, so you spend less on heating. The energy saving alone often has a long payback, but the comfort, reduced condensation and warmer, healthier home are major benefits that the dollar figure does not capture.

How much does double glazing save on power?

It depends on your climate, how much you heat, and how much glazing you have. The saving is the share of your heating bill that the glazing cuts, which this calculator lets you estimate against the install cost.

Is it worth it for an older home?

Retrofitting double glazing is one of the pricier efficiency upgrades, so the pure payback can be long. Many people do it for comfort and to reduce damp and mould, and consider the energy saving a bonus.

Double Glazing Payback Calculator

This New Zealand calculator estimates the payback period on double glazing by weighing the heating energy it saves against the install cost. The pure energy payback is often long, but the comfort, reduced condensation and warmer, healthier home are big benefits the dollars do not capture. You enter the install cost, your annual heating bill and the share double glazing would save, and the tool shows the yearly saving and payback.

Install cost

Annual heating cost

Heating saved by glazing

energy payback period

Saving per year$0

Saved over 20 years$0

This is the energy payback only. Double glazing also improves comfort, cuts condensation and damp, reduces noise and can lift the home's value, which are the main reasons most people install it. Estimate only.

How it works

The calculator applies the heating-saving percentage to your annual heating cost to get the yearly dollar saving, then divides the install cost by that saving for the energy payback period. It also shows the total saving over 20 years. Because retrofitting glazing is expensive, the pure payback is usually long, so weigh it alongside the comfort and health benefits.

Worked example

On a $1,600 heating bill, a 15% saving is about $240 a year. A $15,000 install would take roughly 63 years to pay back on energy alone, saving about $4,800 over 20 years, which is why comfort and health, not payback, are the usual reasons to do it.

Related calculators

Insulation Savings Calculator: insulation savings.
Heat Pump Savings Calculator: heating savings.
Home Heating Cost Calculator: heating costs.
Renovation Value Uplift Calculator: value added.

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