Busting the Myth of “Up to 96% Reduction”: How Site Conditions Affect Real-World RECD Performance
There’s a number that follows RECD technology around wherever it’s discussed: up to 96% reduction. It shows up in product literature across the industry, in vendor presentations, and — in the interest of full transparency — on our own materials too. It’s not a fabricated figure, and we’re not writing this article to walk it back. What we are writing this article to do is separate what that number actually represents from what facility owners often, understandably, assume it represents — because that gap is where a lot of legitimate technology ends up quietly disappointing people who never should have expected it to hit a ceiling their generator was never going to reach.
Myth: “Up to 96%” Is What My Generator Will Achieve
Reality: “Up to” is doing precise, deliberate work in that phrase — it’s describing an upper limit established under conditions specifically favourable to achieving it, not an average or a typical outcome across the full range of real installations.
Published maximum figures for RECD particulate reduction are generally established under conditions that include a well-maintained engine, an appropriate and reasonably consistent load, correct installation, and properly functioning regeneration behaviour. These conditions exist, and some real installations genuinely approach them. But “some installations achieve close to the ceiling under favourable conditions” is a very different claim from “your installation will achieve the ceiling,” and treating the second as automatically following from the first is the single most common source of disappointment in RECD projects.
Myth: A Higher Published Percentage Always Means a Better Product
Reality: A published percentage tells you almost nothing about how a specific product will actually perform on your specific generator, because it doesn’t account for the variables that determine real-world performance — variables that exist entirely outside the product itself.
This is worth sitting with, because it cuts against how most people naturally compare products. If you’re choosing between two RECD systems and one advertises 96% reduction while another advertises 90%, the instinct is to treat the first as simply better. But if the first figure was established under highly favourable test conditions that don’t resemble your generator’s actual operating pattern, while the second was established more conservatively, the products could easily perform comparably — or even in reverse order — once installed on your specific generator. The number alone can’t tell you this; only an evaluation grounded in your actual generator and site conditions can.
Myth: If My RECD Isn’t Hitting the Published Number, Something’s Wrong With It
Reality: Not necessarily — and this myth is worth addressing directly because it can lead facilities toward the wrong conclusion. A properly functioning, correctly installed RECD system operating below its published maximum isn’t automatically malfunctioning. It may simply be operating within the realistic range for your generator’s specific conditions.
That said, this isn’t a blanket reassurance either — a system operating significantly below any reasonable expectation, or one whose performance is degrading noticeably over time, is a genuine signal worth investigating. The distinction is between “below the published maximum” (often entirely expected) and “below what a proper evaluation projected for your specific installation” (worth investigating). This is precisely why establishing a realistic, site-specific expectation during technical evaluation — rather than relying on the published ceiling — matters so much; it gives you an actual, meaningful benchmark to measure real performance against.
What Actually Determines Where Your Generator Lands
Rather than leaving this as an abstract point about percentages, here’s a concrete look at the variables that genuinely determine your real-world result, and why each one matters.
Generator Condition
An engine already dealing with mechanical wear, poor combustion efficiency, or deferred maintenance produces exhaust with characteristics that make it inherently harder for any RECD to reach its published ceiling. This isn’t a limitation of the RECD — the device is treating whatever exhaust the engine actually produces; it can’t retroactively fix upstream combustion inefficiency. A facility evaluating RECD performance should honestly account for the engine’s own condition as part of that evaluation, not treat the RECD as an isolated variable.
Load Profile
As covered in detail in our companion piece on how DPF and DOC technology actually functions, particulate filter regeneration — particularly the preferred, lower-intervention passive regeneration pathway — depends significantly on sustained exhaust temperature, which is itself a function of engine load. A generator running consistently light loads, or cycling unpredictably between light and heavy operation, may not sustain the conditions passive regeneration needs to keep pace with soot accumulation, which has a direct, mechanical effect on sustained filtration performance over time.
Fuel Quality
Diesel quality and contamination levels affect particulate output at the combustion source, before the RECD ever gets involved. Higher baseline particulate generation, driven by fuel quality issues, means the RECD has more work to do to reach any given reduction percentage — and affects how efficiently it can do that work relative to systems operating on cleaner fuel.
Maintenance Discipline
RECD systems, like any filtration and catalytic technology, require ongoing monitoring and periodic servicing to sustain rated performance. A system installed correctly and performing well at commissioning can drift below its realistic performance range over months and years if maintenance is neglected — filter servicing deferred, sensor calibration left unchecked, regeneration issues left unaddressed. This drift isn’t a flaw in the technology; it’s what happens to any precision system left without ongoing attention.
Environmental Conditions
Ambient temperature and broader site conditions influence exhaust behaviour and regeneration cycling, particularly for installations exposed to significant seasonal or daily temperature variation. Sites with more stable, moderate conditions tend to see performance track more closely and consistently against projections than sites with extreme or highly variable ambient conditions.
Installation Quality
Exhaust routing, housing fitment, and sensor placement all affect how closely a real installation’s operating conditions match the conditions under which published performance figures were originally established. A rushed or poorly executed installation — the kind we’ve cautioned against in our article on the full site-assessment-to-commissioning process — can meaningfully undercut even a well-specified, high-quality RECD product.
Why None of This Means RECD Technology “Doesn’t Work”
It would be a mistake to read the above as an argument against RECD technology, and that’s not the intent here. Every one of these variables affects where within a realistic range your installation lands — none of them suggest the underlying technology fails to do what it’s designed to do. A facility that achieves a substantial, well-documented, meaningfully verified reduction in particulate matter and harmful exhaust gases has a genuinely successful retrofit project, regardless of whether that specific number matches a headline percentage from a brochure.
The honest measure of success isn’t “did we hit the published maximum” — it’s “did we achieve a real, verified, meaningful reduction appropriate to our specific generator and site conditions, and can we demonstrate that with proper documentation.” That’s a standard every well-executed RECD project can meet, and it’s a considerably more useful standard than chasing a number that was never meant to describe your specific installation in the first place.
What a Responsible Technical Evaluation Actually Does Differently
Given everything above, here’s what separates a credible RECD proposal from one leaning on marketing shorthand:
It reviews your generator’s condition, load pattern, and maintenance history before offering any performance projection — treating your specific data as the starting point, not an afterthought to a pre-decided number.
It sets a realistic, site-specific performance expectation before installation begins — a range grounded in your actual conditions, explained with reference to the variables most likely to push your result toward the top or bottom of that range.
It explains which factors are most relevant to your situation specifically — rather than presenting a generic list of variables without connecting them to your generator’s actual profile.
It establishes commissioning checks that verify actual performance after installation — rather than simply assuming performance based on the product specification sheet and calling the project complete.
This approach does something a headline percentage alone can’t: it protects the facility from making a purchasing or compliance decision based on an unqualified maximum, and it gives everyone involved a real, meaningful benchmark against which to judge whether the installed system is actually performing as it should.
Frequently Raised Questions on This Topic
If published figures aren’t guaranteed, why do companies advertise them at all? Because they’re a legitimate and industry-standard way of describing technology potential — the issue isn’t that the figures exist, it’s when they’re presented, or interpreted, as a guaranteed outcome rather than a ceiling. A responsible provider uses the published figure as context, not as the specific promise made to any individual facility.
How can I get a number I can actually trust for budgeting or compliance planning? Through a technical evaluation grounded in your generator’s actual data — condition, load pattern, operating hours, maintenance history — rather than relying on a published maximum. This is covered in detail in our article walking through the full site-assessment and evaluation process.
Does a lower realistic estimate mean I should reconsider the RECD investment? Not necessarily — a realistic estimate that’s meaningfully below the published ceiling can still represent a substantial, worthwhile reduction in harmful exhaust emissions, and can still satisfy your compliance obligations. The point of a realistic estimate isn’t to discourage the investment; it’s to make sure the investment decision is based on an honest number rather than an inflated one.
Should I ask a provider to guarantee a specific percentage in writing? This is worth discussing directly with any provider you’re evaluating — a credible provider should be willing to explain what they can and can’t commit to, and why, grounded in the variables specific to your generator, rather than either refusing to discuss performance expectations at all or offering an unqualified guarantee that doesn’t account for real-world variability.
Ask for Your Number, Not the Brochure’s Number
If a proposal for your facility leads with “up to 96%” and doesn’t ask a single question about your generator’s condition, load pattern, or maintenance history, that’s worth treating as a signal to ask more questions before proceeding. Share your DG-set data with our team, and we’ll help you establish a realistic, honest performance expectation grounded in your actual operating conditions — not just the published ceiling.
You can explore the technical detail behind how RECD systems actually work in our companion article on DPF and DOC technology, review our full Retrofit Emission Control Device offering, or check our FAQ page for other questions we’re asked frequently during this evaluation process.