The Conduit: Insight Driving Impact

Q1 2026 | The Conduit: Connected Solutions for a Better Built Environment

The Physics Preventing Comfort

All engineers experience a moment in their career that no one really warns them about.

The project looked fine on paper.

Cooling load matched. Airflow checked out. The coil selection met capacity.

But within weeks of occupancy, complaints started.

Rooms felt cold but damp. Diffusers sweating. Humidity drifting above 65%.

The system was cooling but it wasn’t controlling moisture.

The issue wasn’t equipment size. It was apparatus dew point.

The coil never reached a low enough leaving air dew point to remove latent load under part-load conditions.

When airflow reset and static pressure changed, coil performance shifted and moisture removal dropped even further.

The psychrometrics were correct on paper but the system behavior wasn’t understood.

That’s the moment many engineers realize that temperature is easy and moisture is physics.

Why This Keeps Happening

Here’s a fact that surprises a lot of engineers, especially early in their careers:

The reason usually isn’t undersized equipment.

It’s that moisture behavior is often misunderstood, simplified, or assumed away during design.

Temperature is easy to specify. Moisture is not.

In fact, according to ASHRAE and building science research, humidity-related issues are one of the most common causes of post-occupancy comfort complaints and building performance problems, even in buildings that meet temperature and load calculations.

Southwest Fun Fact

Arizona, New Mexico, and El Paso are all dry but differently.

Arizona sees fast monsoon humidity swings, while El Paso often runs higher dew points than New Mexico, making moisture control critical even when air feels dry.

The Risks

Starting Questions

✓ What Conditions are Physically Achievable?

✓ What Tradeoffs You're Accepting?

✓ Where is Risk Actually Entering the Sytstem?

Psychrometrics exists because air doesn’t behave linearly.

Latent load, ventilation, and part-load operation interact in ways that can't be solved by capacity alone. When those interactions aren’t fully understood, designs can:

Look correct on paper but struggle in operation
Rely on unrealistic assumptions about air conditions
Work only under “perfect” scenarios that rarely exist

This is why psychrometrics feels abstract at first and why it becomes essential later. It’s not about memorizing charts. It’s about understanding constraints

Engineers who ask better questions, set clearer expectations, and design systems that behave closer to intent even when budgets and schedules are tight.

Psychrometrics in Practice

Moisture Fails at Part Load

Most comfort complaints occur at part load, not peak load.

Lower airflow and warmer coils raise apparatus dew point, reducing latent removal — even when sensible capacity looks fine.

This is why systems that “work on paper” fail in operation.

Apparatus Dew Point Moves With Static Pressure

Our Controls Engineering Manager wishes every engineer used more often. But he cautions that changing airflow changes coil surface temperature and bypass factor.

When static pressure resets and airflow drops, coil dew point rises, and moisture removal falls.

This is why humidity problems often appear during low load, VAV turndown, and shoulder seasons.

Engineers should always verify:

Coil leaving dew point at minimum airflow
Not just peak cooling conditions

ASHRAE 55:

Comfort = Temperature + Humidity Stability

ASHRAE Standard 55 shows that comfort complaints increase sharply when RH exceeds ~60%, even if temperature is satisfied.

Temperature control alone does not equal comfort. Control dew point, not just temperature.

Final Thoughts: Part-Load Is the Real Design Condition

Always check performance at low load, low airflow, and shoulder seasons not just peak cooling. Psychrometric failures (high RH, poor latent removal, unstable control) usually show up off design.

With this in mind, always check: