The Real Risk of Rebound
Damien McGill
Engineering Happy Healthy Homes for People and Planet. Certified Passive House Consultant. Certified Passive House Tradesperson.
The Rebound Effect
Our existing housing stock needs to become energy efficient, climate conscious healthy homes.
However, I’ve recently started hearing about something called the “rebound effect” as a reason not to improve energy efficiency in the home.
For example, it was argued on this platform that building Scotland’s houses to passive house standard wouldn’t save any energy and therefore wouldn’t help in saving the planet.
About the same time Newsroom published this article https://www.newsroom.co.nz/sustainable-future/rebound-effect-puts-co2-targets-at-risk?amp=1 which stated
“In the residential sector, the news is good. The rebound effect has “insignificant” impact on residential electricity conservation measures, the study found.” And,
“Energy conservation policies to reduce electricity demand in New Zealand homes may still be effective.”
Phew! Crisis averted!
Or is it?
Let’s back up a bit.
What is the Rebound Effect?
Firstly, the idea is not new. It was first described in 1865 by William Stanley Jevons; These days the Jevons’ Paradox is often called the ‘rebound effect’ - the impact of efficiency measures being the opposite of what is anticipated.
The rebound effect occurs when some of the savings from energy efficiency are cancelled out by changes in people's behaviour. On a consumer level it can be direct (turning up the heating in a newly insulated house) or indirect (spending the money saved on bills on a flight to the Gold Coast).
Turning up the heating is something I can relate to.
My Rebound Renovation
I live in a 2003 built townhouse in central Christchurch, which is undergoing a multi-year upgrade to make it a healthier home. Having triple glazed the windows, I resolved to increase the minimum constant temperature in every room to 18°C, for a 12 monthly power saving of circa $200.
But let’s get real; 18°C is way too cold in winter.
This year, after adding additional insulation in the roof cavity, I’ll be looking to increase the minimum temperature to a more realistic 20°C.
There will be no significant energy savings in this home, until such time as its occupants are comfortably warm, 24/7!
Realising Warmer Rewards
In the New Zealand context, this is exactly what needs to happen. As Gareth Gretton says “What's happening is people are taking back some of the benefit they are getting from increased energy efficiency, and heating their homes more. And those warmer homes are making people healthier because before, the houses were under-heated."
Gretton sees this as a good thing and I must agree.
The Real Risk of Rebound
However, if we continue to tinker around the edges, like the Warmer Kiwi Homes programme is doing, there will be very limited improvement in both energy savings and warm housing. A recent Motu working paper showed that by adding insulation and a heat pump the average temperature of the homes surveyed rose from just over 15°C, to over 17°C while reducing electricity consumption by 16%.
So, an overall improvement of averagely freezing to still pretty darn cold!
I firmly believe that the 16% would be better spent trying to get another degree or two of warmth into these homes by turning up the new heat pump.
Ultimately however, we still have to meet our 2050 climate change requirements of a significant reduction in energy use. Therefore, the very real risk of rebound is then having to go back and re-renovate the renovation.
This is what will happen with the Warmer Kiwi Homes programme and almost every other renovation happening around the country just now.
Real Renovation
There is a real opportunity in front of us, to have one crack at it and get it done properly, first time. This requires three things
1. The Regulatory Framework.
2. An Agreed Outcome.
3. A Renovation Standard.
In my previous article https://www.linkedin.com/feed/update/urn:li:activity:7021229959801180160/, I discussed where the Building Act needs to change. An amended regulatory framework could also include incentives for reaching the agreed outcome.
The agreed outcome should be as a minimum “beyond 2050”. Ministry of Business, Innovation and Employment's Building for Climate Change programme sets a final cap of 75kWh/(m2a) for delivered energy, so this must be the minimum starting point.
Currently the only renovation standard I am aware of that would pass the muster is Passive House Institute's Enerfit standard. https://passipedia.org/certification/enerphit.
As there isn't a New Zealand standard to retrofit homes for energy efficiency, perhaps we should adopt a Kiwi version of #Enerfit for climate change focused renovations, just as Scotland are doing with #passivehouse for new builds?
A great resource that might form the educational basis for this standard could be an Enerfit upgraded version of the BRANZ Renovate site. https://www.renovate.org.nz. It already contains significant detail on the types of houses most likely encountered and would benefit from a facelift.
These three agenda items need to happen urgently, but there is no show of this happening within six months, whomever the elected government is.
Rebound-less
I’d hypothesise that if significant energy savings are made, like the savings Enerfit would bring, it’s very unlikely that the Rebound Effect would come into play inside the home, as the energy saved would be so significant, it would be a struggle to spend the savings just keeping warm and powering devices.
As an example, a recent renovation modelled in PHPP, took the total energy used from over 400kWh/(m2a) to 62kWh/(m2a), a staggering 85% decrease in energy use. (If the home was heated properly to start with).
Whether the Gold Coast is then an option, is of course down to the individual. However, with the increasing cost of living, savings should be gratefully received. A little additional education may be of benefit here...
Combined with solar panels and community batteries, with Kiwirenofit we’d be bounding beyond 2050 and making super progress in providing #healthyhomes for #people and #planetearth!
Additional Sources
https://en.wikipedia.org/wiki/Rebound_effect_(conservation)
https://ukerc.ac.uk/project/the-rebound-effect-report/
https://www.econstor.eu/bitstream/10419/222889/1/1698894252.pdf
https://www.motu.nz/our-research/urban-and-regional/housing/warmer-kiwis-study/
https://www.linkedin.com/feed/update/urn:li:activity:7021229959801180160/
Director at Passive House Academy New Zealand - Kaiako Pūtaiao Hanganga. He pōkeke uenuku i tū ai.
2yDamien McGill As you, I find the arguments in the study as to why the residential sector in NZ is not impacted by a rebound effect not convincing - or rather: I did not discern any, there is no Why. As I have argued in the past, retrofitting in NZ should first and foremost be about making houses safe places to live for everyone: old and young, vulnerable and healthy, rich and poor. Never mind the rebound effect, as long as houses are death traps. But once they are safe to live in, you are quite right that energy savings require a lot more effort than adding insulation here and there, or swapping heating appliances. Most of all, it requires a retrofit plan for every house to use synergies wherever possible, and to not create problems for later steps in the retrofit journey.
"Innovating Net Zero Energy Solutions for Homes through Solar Harvesting and Thermal Storage at EvolutionFX"
2yLots of good information in here and re enforces our continued development on more efficient cooling/heating systems along with the harvesting of free energy as a better solution. Development of our new monoblock hydronic system shows over summer we have been able to down size our 9kw unit to 4kw and achieve the same cooling as last year in the same house. With hydronic systems been able to deliver a "where required" heating/cooling efficient temperature at the correct time of room usesge. The use of water storage when excess free or cheaper energy is available is also a benefit as well as shifting energy usage to off peak. Lots more work to do in this space in the coming months. We wish there was a target for energy consumption on a house we could aim for, other then $1 a day /220m²/Auckland.#EVOHX
Facebook Ads Specialist, founder of Indie Advertising, finding your perfect customers with highly targeted Facebook ad campaigns. Owner of Teetowl, creator of the Bowmaster® artisan bread knife.
2yI still fail to understand why there is so much emphasis on heat pumps which are basically air con units. They're up on the wall which is not the right place for a heat source as heat goes up and not down. When you turn them off the room immediately goes cold, there's no residual heat. Solar heating and underfloor heating which can heat at a much lower temperature to be effective as it covers a larger area, in turn this requires less electricity. It also prevents drafts and heats from the floor up. When turned off the residual heat in the floor and the pipes keeps warming the house. Given NZ houses have mostly wooden floors access to lay underfloor heating is much easier. With a skinny ozone layer I jst cannot fathom why solar hasn't been embraced here when poorer European countries have had it since the 70s and 80s. Coupled with effective double/triple glazed windows (not the cheap aluminium rubbish in the few homes that have it here) there would be a massive saving and achieve much warmer homes.