Double Glazing Payback Calculator

This calculator estimates how long it takes double glazing to pay for itself in New Zealand, by weighing the heating energy it saves against what it costs to install. Double glazing is one of the pricier home efficiency upgrades, and the pure energy payback is often measured in decades, so it helps to see real numbers before you commit, alongside the comfort, warmth and reduced condensation a dollar figure cannot capture. You enter the install cost, your current annual heating bill, and the percentage of that heating cost you expect double glazing to save. The calculator returns the energy payback period in years, the dollar saving per year, and the total saved over 20 years, so you can judge whether the energy case stacks up alone or needs the other benefits to justify the spend. Use it to compare installer quotes, or to see how the payback changes if you heat more or less of the home, or vary your assumed saving percentage. Because glazing replacement is a big-ticket renovation, small changes in the saving percentage or install cost swing the payback period a lot, so treat the percentage as a rough estimate rather than a guarantee. This is an indicative estimate only, based on the figures you enter, and it does not account for finance costs, changing power prices, or the added value glazing can bring to your home.

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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.