Calculating carbon footprint for a Wattwatchers device

image ex Canva tom illustrate blog post on carbon calculations
With action on ‘Net Zero’ surging in Australia and globally, Wattwatchers has been working on better understanding and improving our own carbon footprint, striving for a ‘net positive’ impact on climate change. Here we share our initial assumptions and approach to the carbon equation for our solutions.

You want to know the carbon footprint of a Wattwatchers EnergyIoT device?

It seems like a simple enough question, but predictably getting the answer is not so simple. 

We’ve calculated that on average, for a nominated 5-year operating life, each Wattwatchers device being installed in the field will lead to net reductions in carbon dioxide-equivalent (CO2-e) emissions totalling 860kg (0.86 tonnes), while causing only 140kg (0.14 tonnes) of emissions.

That means over 6kg of CO2-e saved from polluting the atmosphere for every 1kg caused, which is a net positive impact – and our aim is always to do a lot better than just ‘net zero’.

TABLE 1: As you will see from the further estimations and calculations below, we attribute emissions saved of 860kg and emissions caused of 140kg to each Wattwatchers device for a nominated 5-year operating life.

This is calculated after making allowance for the device’s extended life cycle, and its own carbon footprint.

To do this we had to make a number of assumptions and comparisons, and average out some key numbers, because there’s a lot of variability in how our smart energy management solutions are used in the field.

We’ve made this critical assumption for our calculations: a Wattwatchers device, on average, will enable 1,000kg (1 tonne) of carbon dioxide equivalent (CO2-e) emission reductions during a 5-year operating life^. 

(^This is the ‘nominated’ operating life assumed as an average for these calculations. It is not a warranty period, nor a maximum period for using a Wattwatchers device, and individual devices may operate for shorter or longer periods depending on performance, field issues, and customer use cases and management choices.)

Framing our carbon calculations

First, there’s a positive side of the equation, where we help to cut emissions.

This means allocating all of the carbon pollution reductions which result from Wattwatchers devices being installed and used to manage electricity better. 

Then there’s the negative side. 

This means subtracting all of the carbon emissions involved to make the Wattwatchers hardware, including pre-manufactured components; transporting finished products to a warehouse; delivering them to customers; having them installed by electricians; operating them for years powered by electricity; hosting and storing the data in the cloud; and then retiring devices – which ideally will go to e-waste reprocessing for reuse or disposal.

To ensure use of Wattwatchers solutions has a significant beneficial impact for climate change, emissions saved need to substantially outweigh emissions caused. 

The good news from our analysis is there’s a strong upside, with a device’s contribution to reducing carbon footprint being calculated at better than 6:1 when compared with any carbon footprint it causes. And that’s just the carbon benefit side of the equation, because saving and better managing energy means saving money and boosting the value of investments in technologies like solar as well as cutting emissions.

We have a high level of confidence that our calculations provide a sound, ‘in the right ballpark’ evaluation. 

Here’s how we’ve arrived at this conclusion.

The positive side of the story

As indicated, we’ve deemed – we think conservatively, based on our core assumptions – that Wattwatchers devices on average enable 1000kg (1 tonne) of CO2-e emission reductions during a nominated 5-year operating life.

They do this by providing highly-granular data for the smart management of electricity, which supports a range of use cases: energy efficiency, solar performance and optimisation, load control and demand response, grid and network visibility, electric vehicle charging, sustainability rankings and reporting, off-market billing, predictive analytics and maintenance, and more.

As one example, we assume that a Wattwatchers device installed in a household in New South Wales, with annual electricity consumption of 6000kWh, will help reduce the home’s power consumption by 10 percent annually through helping the householders to minimise energy waste, boost efficiency, and achieve best time-of-use and self-consumption of solar (where applicable).

Ten percent of 6,000kWh is 600kWh for 12 months, or 3,000kWh for five years.

Using a carbon calculator to convert kWh into CO2-e, 600kWh translates to roughly 0.49 tonnes per annum of CO2-e, and 3000kWh is 2.46 tonnes of CO2-e (based on standard state-based calculations for grid-supplied electricity in NSW – we’ve used the Powershop online calculator). 

As an indication of how location variability can affect carbon counting, if the same household was in Tasmania the per annum calculation would be only 0.11 tonnes, thanks to the state’s renewable hydropower base; but in brown coal-dominated Victoria it would be considerably higher at 0.64 tonnes per annum.

TABLE 2: State/territory carbon values in tonnes of CO2-e for 600kWh of electricity consumption (i.e. 10% usage saving for an average Australian household consuming 6000kWh per annum).

Because not all devices are installed for this easy-to-understand household use case, and there are so many variables in operating conditions and requirements, we’ve settled on the accumulated average of 1,000kg (1 tonne) saved for the nominated 5-year lifetime.

So, on our numbers, every device we sell adds a tonne of CO2-e as a ‘credit’ on our company’s carbon ledger (although we are not claiming any monetary value for this). As an example, if Wattwatchers had sales exceeding 20,000 devices in a financial year, this would put us a further 20,000 tonnes-plus up on the CO2-e positive side.

But of course it’s not all positive.


Then there’s the negative side

Starting with the biggest single item, there’s the embodied carbon in the hardware itself, through the materials and components used and the manufacturing process itself, plus transport logistics for finished products. 

Then there’s sales distribution and product delivery; installation by electricians; the operational electricity consumption of the devices themselves; and cloud-hosting and storage of the data they collect and transmit.

For embodied carbon in the hardware, we used an Apple iPhone as a reference point for a small, complex, relatively high-value electronic device manufactured from many different components.

For the comparison, we chose the older model iPhone X to allow for the groundbreaking work Apple has been doing in recent times to pursue carbon neutrality for all of its products by 2030

Though shaped differently, and used differently, the internal circuitry of an iPhone and a Wattwatchers device is of similar size, and both transmit data through the cloud. While the Wattwatchers device is about 50% heavier than the iPhone X, it contains less complex electronics, less metals and rare earth materials, and has no screen or battery.

According to Apple’s breakdown, the iPhone X is responsible for total greenhouse gas emissions of 79kg CO2-e across the full product life cycle, with 80 percent (63.2kg) coming from production (including materials and components); 17 percent (13.43kg) from customer use; 2 percent (1.58kg) from transport; and 1 percent (0.79kg) from recycling. 

Wattwatchers accounts for customer use differently, if it applies at all (i.e. emissions relating to use of an app on a smartphone may already be covered elsewhere, so we don’t want to double count them). But we also include additional items in our 5-year life carbon footprint calculations, being: electricity consumption for our devices; product delivery; installation by electricians; data storage; and a rounding up allowance to cover end-of-life or other minor items.

So we have carried forward 65.57kg of CO2-e for this in-the-right-ballpark analysis, being Apple’s full life cycle footprint for the iPhone X less the customer use allocation.

For powering the device, we know a Wattwatchers device on average draws a little under 1.2W of electricity, which is equivalent to 10.512 kilowatt hours (kWh) per annum of energy consumption. Using the carbon calculation for Australia as a whole of 0.6564kg per 1kWh, this means 6.9kg per annum (in the US, which has a lower conversion rate between CO2-e and kWh, it would be 4.5kg).

Multiplying 6.9kg per annum by 5 years gives you 34.5kg for electricity consumption, which adds up to a new sub-total of 100.07kg when combined with the iPhone X allocation we carried forward.

Then we allow an estimated 5kg per device for transport and delivery; 22.3kg for installation, based on an electrician’s light commercial vehicle travelling 100km per installation (at 223g per km, a figure sourced from this June 2020 National Transport Commission report); and 8.645kg for data hosting and storage (1.729kg per device per annum based on a US review published on Medium that estimated 7kWh per gigabyte per annum for cloud storage, but also identified an alternative lower figure of only 3.1kWh per gigabyte per annum – we used the higher number).

All of this adds up to a total of 136.015kg per device for five years, which we’ll round up to 140kg to make an allowance of 3.985kg to cover end-of-life (which Apple estimated at only 1% of the total), accessories and any other minor items. 

(That negative footprint total is only 14 percent of the 1,000kg per device on our credit side, so we’re well ahead with our net positive footprint balance – after subtracting the negative footprint amount – making up 86%.) 

To better illustrate proportions, Table 2 below shows the percentage breakdown of the 140kg of negative carbon footprint in a pie-chart. Emissions embedded in the hardware are the biggest single item (46.8%), followed by powering the device (24.6%). NOTE: We’ve assumed that main grid electricity including fossil fuel generation is powering the devices, although in practice many will run on renewable generation (especially solar) for at least part of most days, providing a further buffer to our calculations.

TABLE 3: Our breakdown of the estimated total (5-year operating life) carbon footprint of a Wattwatchers device, which are depicted as percentages of 140kg of CO2-e.

The assumptions behind our calculations

The biggest assumption we’ve made is our self-awarded upfront credit of 1000kg of carbon emission reductions per device over five years.

Is this reasonable?

We think it is a quite conservative extrapolation from field results Wattwatchers has observed over several years, plus research and other inputs.

The Australian-based life cycle analysis (LCA) company eTool has over a decade of experience in the built environment sector, covering hundreds of sites from both the residential and the commercial and industrial sectors.

eTool cites studies showing that energy monitoring can provide significant savings in electricity consumption. And eTool told Wattwatchers that even though the cited studies show the average savings are between 3.8% and 7%, they assume a 10% energy saving from installing a building-integrated energy monitoring system (Wattwatchers fits their definition for a building-integrated system). This is because the savings are highly dependent on occupant attitudes/behaviour and people that opt in are more likely to achieve larger savings than those that had to opt out.

The other big assumption is comparing a Wattwatchers device with an Apple iPhone X. We see this as a reasonable approximation, knowing both products, and pragmatically we’d rather invest our limited funds in reducing our footprint further rather than repeating expensive micro-analysis to move beyond a good ‘in the right ballpark’ understanding.

Conclusion and next steps

We welcome feedback on this article, and further discussion of our approach, and we are open to revising it as and when better information becomes available. 

Our expectation is that over time our carbon upside as a percentage will increase, and our downside will fall even further, including through product and process design improvements, greater use of renewable electricity, and more effective use of energy data to drive solutions.

Next steps for Wattwatchers include calculating our administrative carbon footprint using the CarbonView tool, delivered by one of our oldest customers, Simble Group; and diving deeper into the carbon footprint associated with our data itself, including using a new tool made available by our cloud hosting provider, Amazon Web Services.

Fun fact No. 1: Weighing in at just under 0.3kg (300 grams), a Wattwatchers device is less than a sixth of the size of a typical utility smart meter (weighing around 2kg), and it’s smarter as well as being a lot smaller in terms of resources consumed to make it.

Fun fact No. 2: Our database currently is headed for 3 terabytes and is growing by 27 gigabytes per week, or 1404 gigabytes a year, adding nearly 10 tonnes of CO2-e per annum to our aggregated carbon footprint for data storage alone. This means working to ensure our customers don’t ‘over store’ data by keeping it for too long, beyond its useful life. Managing this aspect can deliver significant emission reductions, as can selectively culling and compressing data.