Before ASHRAE Guideline 36 existed, every building controls contractor essentially wrote their own sequences of operation from scratch, and the result was a fragmented industry where control quality varied enormously by project, by contractor, and often by geography. Poorly programmed sequences silently consumed energy for years without anyone noticing, because there was no standard to compare them against. Guideline 36 changed that by publishing vendor-neutral, pre-engineered sequences for the most common commercial HVAC configurations — and field studies comparing these sequences against conventional control have documented energy savings ranging from roughly 20% up to 45% depending on the building, season, and baseline being replaced. Facilities evaluating whether their existing sequences already meet this standard can have iFactory AI's team review their current control logic against Guideline 36.
The Standardized Sequences That Replace Guesswork With Documented Savings
iFactory implements and monitors ASHRAE Guideline 36 sequences against your existing BAS, giving facility teams the trim-and-respond logic, dual-max VAV control, and fault detection the standard specifies — verified against real performance, not just installed and assumed correct.
Why a Standard Was Needed in the First Place
Before Guideline 36, "sequence of operation" meant whatever a given contractor had written for a given project — sometimes copied from a previous job with minimal adaptation, sometimes genuinely engineered, and almost never independently verified against a documented benchmark. A building could pass commissioning and still run a control strategy that quietly wasted energy for the life of the equipment, because there was no standard answer for what "correct" actually looked like.
The Sequences Guideline 36 Actually Specifies
Guideline 36 isn't a philosophy document — it's a set of pre-engineered, tested sequences for specific, common HVAC configurations, each one detailed enough that a controls contractor can implement it directly rather than inventing the logic from scratch.
Single and Multi-Zone VAV AHUs
Supply air temperature reset and duct static pressure reset logic for the air handling units that move conditioned air through the building.
VAV Boxes With Minimum Airflow Control
Dual-max control and occupancy-based setback logic for the terminal units that regulate airflow into each individual zone.
Chilled and Hot Water Plants
Demand-based supply temperature reset and pipe static pressure reset for the plant equipment generating chilled and hot water.
Demand-Controlled Ventilation
CO2-based ventilation logic compliant with ASHRAE Standard 62.1, adjusting outdoor air intake to actual occupancy rather than a fixed schedule.
Fault detection and diagnostics are built directly into the sequences rather than bolted on afterward, giving real-time visibility into system health as a byproduct of the control logic itself, not a separate monitoring layer.
See Which Guideline 36 Sequences Your BAS Is Missing
Book a 30-minute session and iFactory AI will review your current sequences of operation against the Guideline 36 specification.
Trim and Respond: The Logic That Changes Everything
Conventional control typically resets a setpoint based on an open-loop input — outdoor air temperature, for instance — and holds a fixed duct static pressure regardless of what the building actually needs at that moment. Guideline 36 replaces that with a closed-loop strategy that continuously adjusts the setpoint based on real-time load, using the minimum energy required to satisfy present demand rather than a conservative fixed target.
The setpoint is regularly reduced at a fixed rate — duct static pressure trimmed lower and lower — conserving energy for as long as downstream zones can still be satisfied.
Once enough zones signal they can no longer maintain control at the reduced setpoint, the strategy flips from trimming to responding.
The setpoint is increased at a fixed rate until the signaling zones can maintain their airflow and modulate their dampers closed again.
The result is a deliberate low-frequency oscillation in the setpoint, hunting for the minimum value that still satisfies the building — a pattern that looks imprecise on a trend graph but is exactly what conserves energy while holding comfort inside tolerance.
Dual-Max Versus Single-Max VAV Control
One of the most consequential differences between Guideline 36 and conventional practice sits at the terminal unit level, in how a VAV box with a reheat coil is allowed to operate.
What the Field Studies Actually Found
Guideline 36's savings claims aren't theoretical — they've been tested in simulation studies and, more convincingly, in instrumented field demonstrations comparing the same building under conventional control and under Guideline 36 control.
| Study | Method | Result |
|---|---|---|
| Lawrence Berkeley National Lab | Whole-building simulation, medium commercial building | 31% average HVAC energy savings |
| Oak Ridge National Lab | Instrumented field test, commercial building test facility | 45% reduction in hourly HVAC energy vs baseline |
| Pacific Northwest National Lab | Large office building emulator, Chicago climate | 41% heating season, 20% cooling season, 18% shoulder season |
| U.S. Department of Energy | Analysis across 14 commercial building types | ~29% average savings from properly implemented controls |
The spread between studies — 18% to 45% — isn't inconsistency, it's a reflection of how much the savings depend on the specific building, climate, and how badly the conventional baseline was performing before the switch. A building running a genuinely broken baseline sequence has more room to improve than one already running reasonably well.
A Composite Scenario: The Sequences That Were Installed but Never Verified
A mid-size office building had a controls retrofit completed several years earlier that the project documentation described as Guideline 36 compliant, and the facilities team had operated under that assumption ever since, with no reason to question it.
A review of the actual running sequences found that while the VAV terminal units were correctly configured with dual-max control, the AHU static pressure reset had been left on a simpler, open-loop schedule tied to time of day rather than the closed-loop trim-and-respond logic the guideline specifies — a gap between what was documented at commissioning and what was actually still running years later. Correcting just that one sequence, without touching anything else in the building, produced a measurable reduction in fan energy that the facilities team hadn't expected from what looked on paper like a minor configuration detail.
Is Your Building a Candidate for a Guideline 36 Retrofit?
Your BAS still runs open-loop, schedule-based setpoint resets
If duct static pressure or supply air temperature resets on a fixed schedule rather than responding to real-time zone signals, the building is running conventional logic, not the closed-loop trim-and-respond strategy Guideline 36 specifies.
VAV terminal units use single-max rather than dual-max control
This is one of the most common and most consequential gaps — single-max control allows the simultaneous heating-and-cooling waste that dual-max is specifically designed to eliminate.
No one has independently verified your sequences against the actual specification
A controls retrofit documented as Guideline 36 compliant at commissioning can still drift or be misconfigured years later — verification against the live running sequences, not the original submittal, is what actually confirms compliance.
None of these gaps are usually visible from the occupant's side of the wall — a building running conventional, open-loop reset logic still keeps people comfortable, which is exactly why the inefficiency can persist undetected for years. The only way these gaps surface on their own is through the utility bill, and by then the building has already paid for a considerable amount of avoidable energy. Catching the gap through a direct sequence review, rather than waiting for the cost to show up somewhere else, is the difference between a planned correction and a surprise one.
iFactory connects to your existing BAS to implement Guideline 36 sequences — trim-and-respond reset, dual-max VAV control, demand-controlled ventilation — and continuously monitors that the running logic still matches the specification, catching drift before it quietly erodes the savings a retrofit was supposed to deliver.
Frequently Asked Questions
What's the actual energy savings we should expect from implementing Guideline 36?
Documented studies show a fairly wide range depending on the building and baseline — a Lawrence Berkeley National Lab simulation found a 31% average, Oak Ridge National Lab field tests measured a 45% reduction in hourly HVAC energy, and a Pacific Northwest National Lab study found seasonal savings ranging from 18% in shoulder seasons up to 41% in heating season. The variation reflects how poorly the existing conventional baseline was performing before the switch, more than any inconsistency in the guideline itself. iFactory AI's team can review your current sequences to estimate a realistic range for your specific building.
What is trim and respond, and why does it matter so much?
Trim and respond is a closed-loop setpoint reset strategy that continuously reduces a setpoint like duct static pressure until zones can no longer maintain control, then increases it just enough to restore control — using the minimum energy required to satisfy real-time demand rather than holding a fixed, conservative setpoint based on an indirect input like outdoor air temperature. It's one of the most impactful single concepts in the guideline because conventional practice typically wastes energy maintaining pressure or temperature margins the building doesn't actually need at any given moment.
Does a Guideline 36 retrofit require new hardware, or is it a software change?
In most cases it's primarily a control logic change rather than a hardware replacement — the sequences are implemented through the existing building automation system's programming, provided the underlying sensors and actuators support the required control points. Some buildings may need additional sensors where existing instrumentation is genuinely insufficient, but the core value of the guideline is standardized, tested logic rather than new equipment. Book a demo to see what a compliance gap assessment would look like against your specific BAS.
How do we know if our building's sequences are actually Guideline 36 compliant right now?
Documentation from an original commissioning project claiming compliance isn't a guarantee that the sequences currently running match that specification — control logic can drift, get overridden during troubleshooting, or simply never have been fully implemented as documented. The only reliable way to know is to review the live running logic against the actual guideline requirements, which is exactly the kind of gap that can persist for years without anyone noticing because the building still functions normally in the meantime.
What's the difference between single-max and dual-max VAV control, practically speaking?
Single-max control uses one maximum airflow limit for a VAV terminal unit regardless of whether it's heating or cooling, which allows a common energy-wasting condition where reheat and cooling airflow work against each other. Dual-max control, the approach Guideline 36 specifies, sets separate maximum airflow limits for heating and cooling modes, constraining reheat airflow independently so the terminal unit isn't simultaneously cooling air down and reheating it back up. It's a relatively small configuration difference with an outsized effect on wasted energy at the terminal level.
Stop Assuming Compliance — Verify It
iFactory implements and continuously monitors ASHRAE Guideline 36 sequences against your existing BAS, catching the gap between what was documented and what's actually running. Book a walkthrough to see where your building stands.
