As the urgency of climate action escalates, the question of sustainability and carbon footprint in our homes becomes more important. A pivotal question arises: How do we measure sustainability in our daily lives, specifically in our homes?
One of the main contributors of carbon in our homes is operational energy, or the carbon used in powering our homes. Measuring daily net zero helps us see exactly where our energy is coming from.
Where our household energy comes from is important. Removing fossil fuels from daily energy use is the biggest single impact any homeowner can make (particularly if you combine the energy for your home with your personal transport such as cars). We have the all the technology and know-how to do this right now.
Key takeaways
Understanding net zero: The (flawed) standard in measuring climate impact
Net zero buildings are based on the idea that a building can offset its energy consumption over a year with the energy it produces.
But as we dive deeper, we see a flaw in this annual approach. The reason? You can be ‘net zero’ and still rely heavily on fossil fuels. You can also be ‘net zero’ and have huge energy bills.
The grid is not a bank
Energy is not stored over long periods for later use, there is no real life credit system.
“Understanding that the grid is not a bank is key to recognizing that current ‘net zero’ accounting could lead to suboptimal building design outcomes. Buildings are being incentivized to include on-site renewable generation, but their arrays are not being sized according to their winter peak load, but rather as if the grid was functioning as a credit system that stores energy for later use.” – Lloyd Alter on Treehugger.
Household energy needs are not uniform throughout the year, and looking at a yearly number obscures the changes in daily or seasonal energy demands.
Hang on, when do we actually use the most energy? The problem with annual net zero
Annual net zero has a critical blind spot: it fails to account for the fluctuations in energy use and solar production throughout the year. Household energy use changes dramatically over the year, with peak use in winter. In fact, in every major city on the east coast of Australia we see the same winter peak, even Brisbane!
Energy surplus in the summer can’t be banked for the winter, leading to a reliance on grid energy during colder periods. Winter grid energy is mostly powered by fossil fuels – a detail lost in the annual calculation – and that means heating our homes in winter is a carbon-intensive exercise.
“Contrary to what one might assume, the cost of the electric grid is not driven by how many kilowatt-hours are consumed over the course of the year, but mainly by the peak demand that that grid must serve. There must be enough power generators, transmission lines, and substations to deliver whatever power is needed on the hottest or coldest (depending on the climate) day of the year. More infrastructure must be added if that peak goes up” – Candace Pearson andNadav Malin, in BuildingGreen
This gap in measurement can lead to a false sense of sustainability, as a house that is ‘net zero’ can still be heavily reliant on fossil-fuel-powered energy during times of the year when renewable generation can’t meet their demand.
Energy is produced and used in a 24-hour cycle. Any metrics around energy and sustainability need to acknowledge this.
A new metric: daily net zero
Enter the concept of daily net zero. Basically: can this home meet its own energy needs within a 24-hour cycle. Does the home generate more energy on a daily basis than it uses? This metric is influenced by the thermal comfort (or star rating), but also by the size of the house, the efficiency of all appliances and solar generation. It’s brings all the pieces of the sustainability puzzle together.
Why is this shift important? Because it ensures homes are designed to be efficient and free from fossil fuels on a day-to-day basis. A house that achieves daily net zero has the potential to operate without fossil fuels. When combined with a battery (either now or in the future) that house is set up to meet the majority of its needs with renewables and even support the household during power outages or other grid disruptions.
It also highlights the key role that winter comfort has in sustainability. Improving the winter energy use of a home is a simple and powerful way to directly impact reliance on baseload fossil fuel power (and save money) .
Once you get to daily net zero, you have the levers to move towards zero carbon. Zero carbon is our goal and how you live and operate in your home will impact how close to zero carbon you get.
Find out the net zero score of your next build project with the Powerhaus app.
Zero carbon is the ultimate goal
Beyond net zero lies the zero-carbon home. It represents a state where homes have no reliance on fossil fuels at any time. Achieving zero carbon means we have successfully decoupled our living spaces from the emissions that contribute to climate change.
Reaching zero carbon requires meeting night-time energy demand with batteries or other renewable technology. While battery technology is still coming down in price, households who want to reduce their fossil fuel consumption can do four things:
- Get off gas – it’s a fossil fuel.
- Build a highly efficient house or renovate an existing house to be more efficient, focusing on minimising heating needs. Heating generally happens at night and when solar production is lowest which means it’s met with fossil fuels.
- Install solar panels.
- Move energy use into daylight hours, a practice called ‘load shifting’. This can have a huge impact, with very little cost. The grid is already decarbonising – when you use energy during the day, it is more likely to already be renewable. Bonus: if you have solar, this action will save you a lot of money.
- Replace fossil-fuel-powered transport with electric: electric cars, or for shorter distances, electric bikes, scooters, skateboards and even golf carts!
Taking action requires a design approach
The journey to daily net zero homes is not just a technical challenge; it requires a holistic view of energy use, production and storage in homes. The best way to get there? Go through a design review process using the Powerhaus app. Look at what the data is giving you and see what is going to have the biggest impact on your daily net zero score.
If you want to measure your daily net zero, it’s one of the key metrics in the Powerhaus app. If you’re building or renovating, use the Powerhaus app as part of your NatHERS star rating certification to easily and intuitively reach a higher rating and a lower carbon impact.
