How Munara's impact dashboard will calculate your CO2 savings

A lot of "your impact" numbers on sustainability apps are quietly meaningless — a big green figure with no explanation of where it came from, which makes it impossible to trust or verify. We'd rather explain the approach honestly, including where the real uncertainty lives, than present a confident-looking number with no methodology behind it.

The underlying approach: lifecycle assessment

The standard way to estimate the emissions avoided by reusing something instead of buying new is a lifecycle assessment (LCA), following the general framework set out in the ISO 14040/14044 environmental management standards. The core idea is straightforward: almost everything we buy carries the large majority of its lifetime emissions in manufacturing — extracting raw materials, processing them, assembling the product, shipping it — rather than in the years it's actually used. When an item is reused instead of replaced, that manufacturing "cost" isn't paid a second time, and that avoided second manufacturing run is what gets counted as CO₂ prevented.

The formula in broad strokes is:

CO2 prevented ≈ emissions to manufacture a new equivalent item
                − emissions from processing/transporting the reused item

The hard part isn't the formula — it's getting reliable, defensible numbers for the first term, because manufacturing emissions vary enormously by material, item, and even by which factory made it.

What real research says about the size of the effect

Rather than invent precise coefficients we can't verify, it's more honest to point at published research on specific categories, which gives a real sense of scale even before Munara's own dashboard is live to calculate per-item numbers automatically:

• Furniture: one sustainability analysis estimated a secondhand sofa's footprint at roughly 10 kg CO₂e, against about 100 kg CO₂e for a new one — a 90% reduction, and separate lifecycle research on reused furniture found comparably steep reductions in the 80–97% range.
• Clothing: the Ellen MacArthur Foundation found that extending a garment's useful life by just nine months cuts its lifetime footprint by 20–30%; one estimate puts the saving from a pre-owned winter coat versus a new one at about 3.7 kg CO₂.
• Electronics: a used smartphone avoids the mining and energy-intensive manufacturing that a new one requires, estimated at roughly 80 kg CO₂ per device in one analysis — and laptops, with more material and a larger battery, are understood to carry a meaningfully larger footprint again.

These are external, cited estimates, not internal platform constants — and they illustrate why furniture and electronics carry outsized impact per item even though they're donated far less often than clothing.

What we count, and what we don't

Being conservative about what counts as "prevented" matters more than showing an impressive number. Once the dashboard calculates item-level figures, our intention is to count:

• Manufacturing emissions avoided by not producing a new equivalent item
• Landfill emissions avoided (particularly methane from decomposing organic materials like textiles and wood)
• A deduction for the transport emissions involved in getting the item to its new owner

And to deliberately leave out, because they're harder to estimate honestly:

• Use-phase emissions (the energy an appliance or device consumes while in use)
• Emissions from the donor's or recipient's personal transport to a handover
• Any credit for a longer-than-average lifespan from unusually good care

Why different platforms show different numbers

If you've compared "impact" figures across different secondhand or donation apps and found they don't agree, that's expected rather than a sign one of them is wrong. Different platforms use different underlying emission factors, make different assumptions about material composition, and credit reuse differently. There isn't yet a single universally agreed coefficient for "how much CO₂ does reusing a wooden chair save," the way there is for, say, converting litres of petrol to CO₂ output. That's exactly why we think the responsible thing is to publish our methodology and sources openly rather than present a number without one.

What we're committing to

As Munara's impact dashboard goes live, our commitment is to use conservative, externally-sourced emission factors rather than optimistic ones, to publish the methodology publicly rather than treat it as a black box, to update the calculations when better published research becomes available, and to show a reasonable range rather than false precision wherever the underlying data is genuinely uncertain. If you want to check a number yourself once the dashboard is live, every calculation should link back to the external source behind it — that's the standard we're holding ourselves to.

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Have a lifecycle-assessment study or emission factor you think we should be using? We'd genuinely like to hear about it — get in touch through the community forum.