What is Plenum in HVAC?
A plenum in heating, ventilation, and air conditioning (HVAC) systems is a box or volume in the building structure that...
UFAD Glossary
Defining HVAC Load
Joe Hullebusch: Feb 28, 2023
The HVAC load is a calculation that determines the building’s heating and cooling requirements. Knowing the HVAC load...
Defining Return Air
Joe Hullebusch: Feb 27, 2023
The return air is the air that returns to the HVAC system from the area that is being cooled or heated. This air flows...
What is Static Pressure?
Joe Hullebusch: Feb 26, 2023
In terms of HVAC systems, static pressure is the resistance against the air flow. Static pressure can emanate from a...
What is VOC?
Joe Hullebusch: Feb 25, 2023
VOCs -- i.e., volatile organic compounds -- are chemicals with molecules that can evaporate very quickly when exposed...
Explaining Thermostatic Controls
Joe Hullebusch: Feb 24, 2023
Thermostatic controls are HVAC controls that let end-users control their heating and cooling by setting the temperature...
LEED Definition
Joe Hullebusch: Feb 23, 2023
LEED is the acronym for the Leadership in Energy and Environmental Design certification. In terms of evaluating and...
What is WELL?
Joe Hullebusch: Feb 22, 2023
The WELL Building Standard is administered by the International WELL Building Institute (IWBI) to assess, score, and...
What is a Building Automation System?
Joe Hullebusch: Feb 21, 2023
A building automation system is a network of computers and devices that allow building owners and managers to digitally...
Explaining CFM HVAC
Joe Hullebusch: Feb 20, 2023
CFM HVAC is an airflow calculation made in cubic-feet-per-minute (CFM). It’s used to determine the cooling requirements...
What is a Skin-Load Dominated Building?
Joe Hullebusch: Mar 25, 2019
In skin-load dominated buildings, energy usage is mostly influenced by the impact of the outside climate on the...
Explaining Sound Transmission Class
Joe Hullebusch: Mar 25, 2019
The sound transmission class (STC) is an integer rating for measuring and classifying how well a building wall or...
Explaining BAS HVAC
Joe Hullebusch: Mar 25, 2019
BAS HVAC refers to the systems necessary for connecting your HVAC system to your wider building automation system...
What is a Smart HVAC?
Joe Hullebusch: Mar 25, 2019
A smart HVAC (heating, ventilation, and air conditioning) system leverages networked HVAC components and other...
What is AHU?
Joe Hullebusch: Mar 25, 2019
‘AHU’ is short for ‘air handling unit.’ It is a system that warms-up, cools, filters, and/or humidifies as well as...
Explaining Inches of Water Column (Inch WC)
Joe Hullebusch: Mar 25, 2019
Inches of water column (inch WC) is a measurement unit for measuring static pressure. It’s a key metric for determining...
What is Stratified Air?
Joe Hullebusch: Mar 25, 2019
Stratified air -- also known as thermal stratification -- occurs when cool, dense air sinks while the warm and thin air...
What are Diffuser Grilles?
Joe Hullebusch: Mar 25, 2019
Diffuser grilles are the outer frames you can use to enclose your variable air volume (VAV) or air supply diffusers....
Explaining Environmental Controls
Joe Hullebusch: Mar 25, 2019
An environmental control device is an instrument that equips the end-user to control the area’s heating and cooling....
What is a Supply Diffuser?
Joe Hullebusch: Mar 25, 2019
In HVAC systems, the air supply diffuser is a device that delivers and ventilates conditioned air in an area, mixes...
What is Perimeter Heating?
Joe Hullebusch: Mar 25, 2019
Perimeter heating is a method of distributing warm air through ducts installed in the surrounding area of an indoor...
Defining Air Duct Velocity
Joe Hullebusch: Mar 25, 2019
The air duct velocity -- also known as air flow velocity -- is a measurement of the air that moves through your HVAC...
Defining Supply Air
Joe Hullebusch: Mar 25, 2019
The supply air is the outside air that the HVAC system’s air handling unit (AHU) brings in and filters. The AHU then...
1 min read
What is a Chilled Beam?
Joe Hullebusch: Mar 25, 2019
Chilled beam systems are a type of HVAC system that omits fans in favor of using fin-and-tube heat exchangers. The main...
Slab-to-Slab Height
Joe Hullebusch: Mar 25, 2019
The slab-to-slab height is the height between an interior space’s true ceiling and true floor. The ‘true ceiling...
Defining Fan Efficiency Grade
Joe Hullebusch: Mar 25, 2019
A fan efficiency grade (FEG) is a measurement for determining an HVAC fan’s energy efficiency. The FEG measures the fan...
What is Value Engineering?
Joe Hullebusch: Mar 25, 2019
Value Engineering (VE) is an approach of analyzing and designing building systems -- such as HVAC -- to deliver the...
What is a Fan Coil Unit?
Joe Hullebusch: Mar 25, 2019
A fan coil unit (FCU) is a standalone HVAC (heating, ventilation, and air conditioning) system that treats and/or...
What is a Linear Grille?
Joe Hullebusch: Mar 25, 2019
Linear grilles are designed to cover sidewall, ceiling, and floor-based air diffuser/air supply and return systems. As...
Explaining Air Leakage
Joe Hullebusch: Mar 25, 2019
In terms of HVAC systems, air leakage is when outside air penetrates your home or building via cracks, holes, or other...
What is VAV in HVAC?
Joe Hullebusch: Mar 25, 2019
A VAV -- i.e., Variable Air Volume -- HVAC (heating, ventilation, and air conditioning) system that supplies air at...
What is Air Throw?
Joe Hullebusch: Mar 25, 2019
The air throw value is the velocity measurement of how well the air shifts from the vent or diffuser to the rest of the...
Air Distribution
Joe Hullebusch: Mar 25, 2019
The sole purpose of an HVAC (heating, ventilation, & air conditioning) system, air distribution -- also known as room...
What is a Subfloor?
Joe Hullebusch: Mar 25, 2019
The subfloor is the layer above the joist, but below the underlayment (which is the layer below the surface). The...
2 min read
Why UFAD?
Joe Hullebusch: Dec 23, 2015
Underfloor Air Distribution (UFAD) is an air distribution strategy where heated or cooled conditioned air is...
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