Terry McWilliams is a building-performance practitioner and HVAC diagnostic specialist with extensive hands-on experience evaluating how mechanical systems interact with airflow, building pressure, ventilation, moisture, and the building enclosure. Based in the Greater Houston area, Terry specializes in identifying the root causes of persistent comfort, humidity, condensation, indoor environmental quality, and HVAC performance problems in hot-humid climates.
Terry has developed his expertise through residential and light-commercial HVAC service, installation, system design, airflow balancing, duct-system optimization, commissioning, and whole-building diagnostic testing. His field experience allows him to evaluate more than the equipment itself—examining how design decisions, installation quality, duct performance, controls, ventilation, and enclosure conditions affect the operation of the complete building.
Terry approaches each investigation with the understanding that persistent building-performance problems rarely result from one isolated component. Equipment capacity, sensible and latent performance, delivered airflow, static pressure, duct leakage, outdoor-air infiltration, room-pressure relationships, attic conditions, drainage, and control strategies must all be considered together. By combining HVAC measurements with enclosure and pressure diagnostics, he develops practical, data-driven recommendations based on how the building actually performs.
His work is particularly focused on the challenges found along the Texas Gulf Coast, including elevated outdoor dew points, uncontrolled infiltration, inadequate latent capacity, condensation within vented and unvented attic assemblies, poorly performing duct systems, oversized equipment, ventilation deficiencies, and communication pathways between conditioned and unconditioned spaces. Terry’s objective is to translate complex field data into clear corrective strategies and then verify that the completed work delivers the intended result.
HVAC Performance Consulting
HVAC diagnostics and troubleshooting
Residential and light-commercial performance evaluations
Equipment-capacity and application review
Sensible and latent performance analysis
Airflow and static-pressure diagnostics
Duct-system evaluation and optimization
Zoning and room-pressure analysis
Ventilation and dehumidification strategy
HVAC controls and sequence-of-operation review
Quality assurance and commissioning
Corrective-scope development
Post-correction performance verification
Blower-door infiltration testing
Duct-leakage testing
TrueFlow airflow measurements
Airflow-hood testing and system balancing
Zonal and room-pressure diagnostics
Thermal-imaging analysis
Temperature, relative-humidity, and dew-point monitoring
Indoor-air-quality screening
Combustion and carbon-monoxide testing
HVAC load calculations
Building and mechanical-system performance verification
Humidity and condensation investigations
Dew-point and moisture analysis
Dedicated dehumidification applications
Outdoor-air and ventilation assessments
Vented and unvented attic performance
Ductwork located outside the conditioned enclosure
Mechanical-system and building-enclosure interactions
Infiltration and uncontrolled outdoor-air pathways
Latent-capacity and moisture-control deficiencies
Terry is an advocate for integrating building science, measured diagnostics, and disciplined craftsmanship into everyday HVAC practice.
His industry involvement includes:
Advisory committee member, San Jacinto College
Speaker, 2026 National Comfort Institute High-Performance HVAC Summit — “Accuracy Is a Mindset”
Graduate and former keynote speaker, SER Jobs
Industry collaboration involving HVAC diagnostics, airflow, moisture control, indoor environmental quality, and workforce development
BPI Building Analyst Professional
National Comfort Institute Residential Air Balancer
National Comfort Institute Duct System Optimization
NATE Certification
EPA Section 608 Certification
OSHA and NCCER Training
Texas Licensed Air Conditioning Contractor — TACLA77699C
High-Performance HVAC
Building Performance Diagnostics
Hot-Humid Climate Investigations
Humidity and Moisture Control
Airflow and Static-Pressure Analysis
Duct-System Performance
Ventilation and Dehumidification
Building-Pressure Diagnostics
Indoor Environmental Quality
Mechanical-System Commissioning
Corrective-Scope Development
Performance Verification
Independent by Design
Tell us what you are seeing, what has been proposed, or what decision you are evaluating. We will help determine the right next step.
