Introduction: Well-Insulated Home Means More Comfort From Each Unit OF Heat
In fact a well insulated home is so insulated and air-tight that they only need the sun, people living inside, appliances and some heat recovery to stay comfortable in the winter. In the summer, the same principles means little heat getting in and little cold leaving so the interior stays comfortable. These homes are called passive houses. Jump here if you’re just looking for simply the best insulation for your home.
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 bill, heating fuel use, heating cost comparisons, home 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.
Comparing Three Types Of Homes: Value Of Good Insulation
In the image bellow 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.
Above the line are all the heat gains from active heating with a furnace or heater, the sun, cooking etc. Below the line are all the losses through walls, roof, windows etc. In a leaky house, you need a lot of heat to balance out the losses to be comfortable.
In the most extreme efficient house, the Passive House (see below), only a little bit of heating is needed to counteract the losses. In fact, 20 times less. Now we will examine what characteristics define passive, modern and leaky houses.
Characteristics Of A Leaky House (Poorly Insulated) – 300 kWh / sq m
The poorly insulated house or a 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 .
Worse, moisture and/or heat gets into the house. This leads to mold, mildew, and other problems. For a big house of 185 square meters (which is a little over 2,000 square feet), that’s 55,000 kWh, or 200 million BTU per year.
Considering that the average American household uses 10,000 kWh per year, the heating and cooling costs for a leaky house are 5 times higher and therefore enormous.
Characteristics Of A Modern House (Well Insulated) – 150 kWh / sq m
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. For a big house of 200 square meters that’s 30,000 kWh or 100 million BTU per year. This is the normal situation.
Characteristics Of A Passive House: (Next-Gen Super-Insulated) – 15 kWh / sq m
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 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. We’re excited about this area and feature stunning examples of passive houses. For a big house of 200 square meters, the annual energy use is 6,000 kWh or 20 million BTU per year.
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. For comparison, a big high efficiency fridge might use $50-$100 per year. In colder climates, the costs for heating go up, and the savings will go up too.
Assess For Your Own House
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.
What Is A Building Envelope?
The building envelope, or building enclosure, are all the elements of a building that separate the inside from the outside. The architecture and construction of the envelope is a specialized area.
In the context of carbon reduction and environment, the building envelope plays an important role. To have a well insulated home means having a good building envelope.
Having a good building envelope means two things: 1) reduced influence of weather conditions on the building interior, 2) reduced loss of heating and cooling from the interior to the exterior.
First, Look For Low Cost Solutions
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 draught-proofing. Loft or attic insulation might be next. Wall-cavity insulation if you have any. Floor covering and curtains may be old school, but can be really worth it if you’re on a budget or renting.
Second, Look At High Cost, Slow Return Solutions
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.
Picking the right window that have the correct insulating properties, and satisfy the aesthetics of your house, isn’t easy. Once you picked out the windows, you’ll need to find the right people to install them who work efficiently, and who work well so the labor costs aren’t overwhelming.
In the end it’s not unusual to be paying $1,000 per window and so for 10 windows you’re looking at a $10,000 home improvement project.
Finally, Consider Foundational Architectural Solutions For A Well-Insulated Home
The best time to build a superior building envelope, is at the beginning of construction. The concept of the Passive House mentioned above is best designed and implemented with an architect. It’s not without added cost.
Making a house up to the Passive House standards will increase the construction cost by 5% to 10%. For a $500K home, that’s $25K to $50K. For the expensive, cold climate states, the energy savings could be $2k to $3k per year.
While considerable, you would be recovering the cost slowly over a decade or two. However, don’t forget the ancillary benefit is the massive carbon reduction.
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.
Lindsay Wilson
I founded Shrink That Footprint in November 2012, after a long period of research. For many years I have calculated, studied and worked with carbon footprints, and Shrink That Footprint is that interest come to life.
I have an Economics degree from UCL, have previously worked as an energy efficiency analyst at BNEF and continue to work as a strategy consultant at Maneas. I have consulted to numerous clients in energy and finance, as well as the World Economic Forum.
When I’m not crunching carbon footprints you’ll often find me helping my two year old son tend to the tomatoes, salad and peppers growing in our upcycled greenhouse.