Energy creep…more energy efficient homes don’t necessarily mean people use less energy

By Ken Collins 23/04/2010

New Scientist magazine ran a brief report on research into energy use in houses after they were made more energy efficient. Conducted in the UK, it highlights that after insulation, double glazing and energy efficient heating is installed the amount of energy used is still close to the old levels, prior to the improvements.

The article says that some people who have made their houses more energy efficient are more likely to indulge in small excesses — turning up the heating or keeping it on for longer. Kevin Lomas of Loughborough University, UK — who was part of the research team that carried out the surveys — is quoted as saying:

’…..often they are more concerned about comfort than saving energy.’

Or, perhaps they think that because their house is more energy efficient they can indulge in being more comfortable and still save energy.

Whatever the reasons, is this the law of unintended consequences at work? Is it human nature to use as much energy as it takes to be comfortable, to the point that it hurts the wallet? Does having more energy efficient homes actually reduce energy use significantly, or does it just allow us to be more comfortable?

Certainly there have been media reports of people installing energy efficient heat pumps and then getting power bills twice what they were before. That is because they ran these things all day and all night thinking there were cheap to run. Yes, heat pumps are cheap to run, but they still cost a lot when you run them all day every day.

By way of example, one of the guys in the office was talking about how the nights are getting colder. It wasn’t cold enough for him to be bothered to light his wood burner, so he put on a jumper. Later in the night he heard the neighbours heat pump going. So, was the use of heating based on a heat pump being too easy to turn on, for instant reward?

The point is that the highly publicised and popular schemes to insulate older homes in NZ may backfire a little, in that not nearly as much energy will be saved as anticipated, or worse still even more energy is used because of an efficiency perception.

The relative merits of various energy sources to heat homes was provided graphically by Right House recently. Their business is to provide advice on energy efficient home design and performance, as well as individual products.

They show comparisons on various types of energy and their costs for NZ conditions. Interestingly enough, fire wood is the cheapest fuel per kWh of heat by far and the cheapest cost to run per year, despite it being the least efficient.

Electricity on the other hand is the third highest cost per unit, but is the most efficient at turning energy into warmth. The result is that a heat pump is also has the cheapest yearly running cost, making it the same as firewood.

heating-cost-comparison Fuel-Prices


Therefore the amount of energy required to heat a home comfortably is a combination of selecting the right heating method for the size and style of the house, as well as how the occupants use the house, and how ’comfortable’ they want to be.

However, a noticeable trend is the significant shift to using electricity as the energy source. In NZ it is perceived as being clean and green with our significant use of  hydro and geothermal generation.

NZ is already under pressure with the need for more generation and no-one wants new wind turbines or hydro power stations in their back yard, let alone nuclear. But with the ever increasing move away from burning things to provide heat, to switching things on, the pressure to provide more generation may force our hand.

We may end up needing to burn things to allow us to switch things on. It’s all a matter or perception really.

0 Responses to “Energy creep…more energy efficient homes don’t necessarily mean people use less energy”

  • On the other hand, if your grandmother feels she can afford to heat her house, instead of shivering all winter, that doesn’t seem like a waste, and maybe there will be payoffs later in terms of less stress on the health system?

    • Yes I agree, however there is a difference between housing that is healthy and provides a healthy environment (which would be seen as a minimum), and providing a level of comfort. Over and above the minimums needed for a healthy environment, higher levels of insulation and more energy efficient heating systems are seen (promoted) as a way to reduce energy use, carbon footprint, and all. However research and observation tends to show that a reduction in energy use is not happening to the extent anticpated, partly because people adjust their comfort levels (or their expectation of comfort levels) as well.

  • An increase in insulation and energy efficiency would definitely raise my energy use. As things are, I don’t generally bother to heat at all, because the place is so draughty and completely uninsulated that the electric heating available could be cranking along but make no difference to the indoor temperature whatsoever, so in winter I put on thermals and sheepskin slippers and fingerless mitts and a thick jumper, and stay warm while enjoying the fresh air from open windows. Any improvements that made it possible for an electric heater to have an effect would increase my use from ‘hardly at all’, to ‘occasionally’.

  • Putting this in terms of “comfort levels” rather underplays the benefits.

    The key benefits of retrofitting insulation are the health benefits, especially to occupants with asthma and other respiratory symptoms. Poor housing in NZ is responsible for 1,500 excess winter deaths, so reducing this seems like a very cost-effective way of preventing people from dying.

    This kind of take-back effect has been pretty well studied in NZ, thanks to Phillippa Howden-Chapman’s work. They still show an energy saving of 10-15%, on top of saved lives.

    Here’s one of that research group’s recent articles (sadly not online for free):
    “Warm homes: Drivers of the demand for heating in the residential sector in New Zealand”
    Energy Policy, Volume 37, Issue 9, September 2009, Pages 3387-3399
    Philippa Howden-Chapman, Helen Viggers, Ralph Chapman, Des O’Dea, Sarah Free, Kimberley O’Sullivan

  • Thank you for the reference Jez. The blog was not a call for homes to remain un-insulated, there is no debate that homes need to be healthy and provide a healthy environment. Insulation is one significant component to a healthy environment inside a building, and there are numerous others.

    However there has been little discussion or information publically that there is a noticable “take-back effect”, and what impact that is having on energy use. Insulation of itself is one side of the coin. Selecting the best heating methods (for the specific building), and understand how that energy is best used is the other.

    This blog certainly wasn’t a call to stop improving the insulation value in housing, but more of a general look at how human nature can impact on anticipated results.

  • Understood, Ken. I’ve been following the energy efficiency debate for a variety of reasons, not least because we’re building a passive solar/wood heated home myself.