Published on November 26th, 2013 | by Shrink That Footprint


What Is The Value Of A Well Insulated House?

November 26th, 2013 by  

Originally published on Shrink That Footprint
by Lindsay Wilson


The better insulated and air tight your home is, the more comfort you get from each unit of heat.

In fact, homes can even be so well insulated and air tight that they only need the sun, bodies, appliances, and some heat recovery to stay comfortable. These homes are called passive houses.

In this final post of our Beginner’s Guide to Heating Bills, we’ll look at why good insulation is so valuable. Having touched on the average heating billheating fuel useheating cost comparisonshome heat loss, and thermostat temperature settings, it makes sense to finish with insulation.

You see, if you have exceptionally good insulation, you don’t need to worry about heating bills at all.

The Value of a Well Insulated House

In the image above, we depict the heat gains and losses for a ‘leaky house’, a ‘modern house’, and a ‘passive house’. While it is tempting to look at heat gains first, it is actually the losses that explain what is going on.

The leaky house has solid walls, poor loft insulation, an uninsulated floor, single glazed windows, and lots of draughts. Because of this, it needs 300 kilowatt-hours of heating for each square meter of space per year (kWh/m2a) just to stay warm.

The modern house has insulation in the wall cavity and loft, an insulated floor, double glazing, and some draught excluders. Because of its better insulation, it needs just half the heating of the leaky house, 150 kWh/m2a, to maintain a similar internal temperature.

The passive house has superb insulation in all materials, triple-glazed windows that face the equator to maximize solar gains, and is so air tight that it uses a ventilation system to keep the air fresh. It needs just 15 kWh/m2a of heating, some of which comes from heat recovery in the ventilation system.

What does this mean in simple terms? The leaky home’s heating bill might be $1,500 a year, $750 for the modern, and $100 for the passive house.

What Does this Mean for Your Home?

Although this looks simple on paper, really good insulation is actually rocket science. And annoyingly for most of us, investing in good insulation makes most sense when a home is originally built. Cost-effective retrofits take real talent.

That said, if you own your own home, many types of insulation are a good investment. The colder your climate and the higher your fuel costs, the better the paybacks are.

As a general rule, you want to investigate the cheapest ways to improve your building’s envelope first. This will probably start with caulking and draughtproofing. Loft or attic insulation might be next. Then wall cavity insulation if you have one. Floor covering and curtains may be old school, but can be really worth it if you’re on a budget or renting.

For major expenses like upgrading windows and external wall insulation, the payback can be glacial, so you should really do your research and also factor in value changes to your home.

I hope you enjoyed the Beginners Guide to Heating Bills!! In the future, we hope to add more of a practical ‘how to’ guide about cutting heating bills, but this is a decent starting point to understanding your heating bills.

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Shrink That Footprint is a resource for squeezing more life out of less carbon. We are an independent research group that provides information to people interested in reducing their climate impact. Our core focus is understanding, calculating, and reducing personal carbon footprints.

  • juxx0r

    Our house’s heating and cooling bill was 23 cents in a year with no triple glazing, no double glazing, no wall insulation, just a well designed house with roof insulation in a moderate climate.

    If we had triple glazing, we’d have to open the windows all the time to cool the joint down.

  • anderlan

    10ft^2 ~= 1m^2. At 10cents/kwh that’s around $2000 for a 1500sqft modern house. NOW, multiply that over the mortgage term of 30 years, and that’s $60,000!

    • sean

      it would seem logical to legislate all new homes to have really good insulation, but good luck getting that through an election!

  • Takeshi

    An interesting article. And given that something like 40% of North American energy consumption is related to heating, cooling, and lighting our buildings, this information is important too.

    I bought a 70 year-old 1200 sqr foot home back in 2010. Since then, I have put in new triple-pane windows to replace the old cracked ones, installed weather strips around the doors, and put spray foam in the otherwise uninsulated walls. The effects have been dramatic. Our heating bills are less than half of what they were previously.

    It does cost capital, which can hurt, but in the long run the payoff is there.

  • My Master’s degree thesis was on the French residential sector and there I found out data very similar to yours regarding energy needs per square meter per annum.

    Your post is absolutely excellent as I have been wondering ever since if France was doing better or worse than other countries. As your data shows, it is doing in an average way.

    Keep up the good work 🙂

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