The 80/20 Pattern in Building Decarbonization
In business, the Pareto principle (the idea that 20% of actions create 80% of results) shows up everywhere. It also applies to the way buildings decarbonize.
Most portfolios still treat carbon reduction as a capital-projects problem: new chillers, new boilers, new equipment. These projects are visible, expensive, and easy to headline in ESG reports. But in practice, the biggest near-term gains lie in the systems that are already running every hour of every day.
According to the U.S. Energy Information Administration, space heating, cooling, and ventilation are among the top energy end-uses in commercial buildings, with ventilation alone consuming nearly 10% of the total building energy. Factor in heating and cooling, and the air systems you already own set the floor for your emissions profile. Industry surveys and guidance reinforce this point: HVAC systems consistently account for approximately 40% of energy use in commercial facilities. A share that shifts by climate zone but remains dominant across the board.
Before you buy new megawatts, make the watts you already use travel a shorter, smarter, more efficient path.
Filtration as a carbon multiplier (not a consumable line item)
Why filtration matters for energy (and CO₂e)
Filters impose a pressure drop; fans work against that resistance. Basic fan/affinity laws tell us that pressure rises with the square of fan speed, and fan power typically scales with pressure/flow requirements. Therefore, adding resistance increases fan energy unless the system compensates by reducing the flow.
On variable-speed systems that maintain flow, peer-reviewed work shows roughly linear fan-power response to added system pressure: a 10% rise in total pressure drop ≈ 10% rise in fan electric power (assumes fan and motor efficiencies roughly constant at operating point). CaEE
Field and lab studies show that higher filter resistance reduces supply airflow and can increase total power (especially as filters load), degrading cooling capacity and forcing longer runtimes. Newer research also documents the compounding effects of filter loading, with heavy clogging cutting net supply airflow by >30%, a textbook example of invisible energy waste. ScienceDirect
Moving up in MERV doesn’t automatically mean higher energy costs. Well-designed filters use optimized media and geometry (like deeper pleats or more surface area) to keep airflow resistance low. Studies have shown that these higher-efficiency filters can have a lower pressure drop than inexpensive MERV 8 pleated filters, especially when systems are properly balanced. In other words, it’s the filter’s pressure profile that matters, not just the MERV number. ScienceDirect
If you can lower your filter pressure drop while maintaining or improving capture, you directly reduce continuous fan energy. One of the few all-hours loads in many facilities. Because fans run whenever you condition or ventilate space, these savings translate cleanly into CO₂e reductions (see Section 5 for the math).
Demand-Controlled Ventilation (DCV)
What DCV does
It modulates outside-air intake based on occupancy (CO₂, people-count, scheduling) to avoid conditioning empty spaces. Codes and standards increasingly require or encourage DCV in high-occupancy areas, with ASHRAE 62.1 updates clarifying when and how ventilation turndown is permitted (including addenda that allow reduction to zero OA during verified unoccupied periods in certain space types). ASHRAE
Across building types and climates, published work shows that DCV control logic achieves ~9–33% HVAC energy savings. Advanced rooftop-unit control packages, which incorporate multi-speed/variable fans, DCV, and smarter economizer control, have delivered double-digit fan and cooling savings, sometimes exceeding 20%. Taylor & Francis Online
Lawrence Berkeley National Laboratory (LBNL) analyses flag that cost-effectiveness depends on the baseline over-ventilation and occupancy patterns; if your current minimums are already close to code, savings shrink. That’s a guidance feature, not a flaw—the point is to measure your baseline VRs before projecting benefits. Energy Technologies Area
DCV is a surgical lever: attack over-ventilation where it exists, prove reductions with trend data, and lock in permanent load reductions; especially valuable in heating-dominated regions where conditioning outside air is expensive in both energy and CO₂e. Energy Codes Guide
Preventative Maintenance
Controls drift, coils foul, dampers stick, sensors mis-calibrate—quietly taxing 5–15% of portfolio energy in many studies. Modern fault detection & diagnostics (FDD) tools and structured maintenance programs quickly recapture that waste. NREL Docs
Coil fouling: Government and academic sources document material energy penalties from dirty coils; some guidance cites compressor energy up to ~30% higher with fouled condensers (case and climate dependent). Even conservative findings confirm meaningful efficiency and capacity degradation. Avoidable with routine cleaning. Energy.gov.au
Economizers & OA paths: Mis-tuned economizers are common and costly; retuning and sensor QA via FDD is repeatedly highlighted in DOE/NREL/PNNL guidance as a top-tier low-cost fix. PNNL
RTU controls refresh: Campaign results and tech briefs demonstrate that advanced RTU control (variable fan, DCV, and economizer optimization) consistently yields energy reductions of more than 20%, with 25–50% reductions cited in certain deployments compared to legacy constant-speed, always-open baselines. Better Buildings Solution Center
Maintenance is mitigation. It’s also Scope 3-friendly: operating equipment at design efficiency extends service life and defers replacements, reducing embodied carbon churn in your capital plan. (See the measurement plan below to make these savings auditable.)
Turning kWh into CO₂e: a quick, defensible method
Your sustainability stakeholders care about tons, not watts. To translate HVAC savings into CO₂e:
Quantify energy from the measure (e.g., fan kWh drop from low-pressure filters; heating/cooling kWh or therms saved from DCV; kWh saved from FDD fixes).
Apply grid or fuel emission factors appropriate to the site(s) and year.
U.S. electricity (2022 eGRID avg): ≈ 0.393 kg CO₂/kWh (867.5 lb/MWh delivered). US EPA+1
Canada electricity (2025 factors) vary widely by province—e.g., Ontario: 38 g CO₂e/kWh; Alberta: 490 g CO₂e/kWh. Selecting the right regional factor matters. Canada.ca
If a low-pressure filter reduces fan energy by ~300 kWh/year per unit (magnitude depends on hours, fan size, and baseline pressure):
This is why portfolios across different grids see very different CO₂e per kWh outcomes. Even when the kWh savings are identical. US EPA
For transparency in ESG filings, reference the EPA eGRID subregion or the Government of Canada tables (or your utility-specific factors) and archive the PDFs used for each reporting year. US EPA
Risk management & IAQ alignment
Stay within ASHRAE 62.1 minimums at all times when spaces are occupied. DCV is about right-sizing, not starving air. Updated addenda clarify occupancy-based turndown rules—use them. ASHRAE
Filter choices: Seek equal or higher capture with lower ΔP; measure clean and loaded ΔP at your own face velocities. Research shows energy impact depends on filter design and system configuration, not only MERV. ScienceDirect
Measurement culture: Treat IAQ and energy as co-optimized objectives by trending PM, CO₂, temperature, and fan power together, so nobody is flying blind.
What this unlocks for 2026 capex
Once you bank the operational tons above, the economics of electrification, heat recovery, and heat pumps improve because you’re sizing for reduced loads. DOE/NREL work on advanced RTU control consistently shows meaningful kWh reductions when variable fans and DCV are layered in—think of these as pre-project multipliers that de-risk later capex. NREL Docs
The Power of the Overlooked 20%
In the rush to decarbonize, it’s tempting to chase the biggest, newest technologies. But the truth is that many of the most reliable carbon savings are already within reach. Hidden in fans, filters, ventilation rates, and maintenance routines.
Filtration, demand-controlled ventilation, and preventative maintenance may not make the headlines, but together they represent the overlooked 20% of actions that can deliver 80% of your emissions savings. They are measurable, repeatable, and scalable across portfolios, exactly the kind of solutions facility leaders need as they enter a new year of climate commitments.
