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
Feb 28, 2023 by Joe Hullebusch
The HVAC load is a calculation that determines the building’s heating and cooling requirements. Knowing the HVAC load...
Defining Return Air
Feb 27, 2023 by Joe Hullebusch
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?
Feb 26, 2023 by Joe Hullebusch
In terms of HVAC systems, static pressure is the resistance against the air flow. Static pressure can emanate from a...
What is VOC?
Feb 25, 2023 by Joe Hullebusch
VOCs -- i.e., volatile organic compounds -- are chemicals with molecules that can evaporate very quickly when exposed...
Explaining Thermostatic Controls
Feb 24, 2023 by Joe Hullebusch
Thermostatic controls are HVAC controls that let end-users control their heating and cooling by setting the temperature...
LEED Definition
Feb 23, 2023 by Joe Hullebusch
LEED is the acronym for the Leadership in Energy and Environmental Design certification. In terms of evaluating and...
What is WELL?
Feb 22, 2023 by Joe Hullebusch
The WELL Building Standard is administered by the International WELL Building Institute (IWBI) to assess, score, and...
What is a Building Automation System?
Feb 21, 2023 by Joe Hullebusch
A building automation system is a network of computers and devices that allow building owners and managers to digitally...
Explaining CFM HVAC
Feb 20, 2023 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
In skin-load dominated buildings, energy usage is mostly influenced by the impact of the outside climate on the...
Explaining Sound Transmission Class
Mar 25, 2019 by Joe Hullebusch
The sound transmission class (STC) is an integer rating for measuring and classifying how well a building wall or...
Explaining BAS HVAC
Mar 25, 2019 by Joe Hullebusch
BAS HVAC refers to the systems necessary for connecting your HVAC system to your wider building automation system...
What is a Smart HVAC?
Mar 25, 2019 by Joe Hullebusch
A smart HVAC (heating, ventilation, and air conditioning) system leverages networked HVAC components and other...
What is AHU?
Mar 25, 2019 by Joe Hullebusch
‘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)
Mar 25, 2019 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
Stratified air -- also known as thermal stratification -- occurs when cool, dense air sinks while the warm and thin air...
What are Diffuser Grilles?
Mar 25, 2019 by Joe Hullebusch
Diffuser grilles are the outer frames you can use to enclose your variable air volume (VAV) or air supply diffusers....
Explaining Environmental Controls
Mar 25, 2019 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
In HVAC systems, the air supply diffuser is a device that delivers and ventilates conditioned air in an area, mixes...
What is Perimeter Heating?
Mar 25, 2019 by Joe Hullebusch
Perimeter heating is a method of distributing warm air through ducts installed in the surrounding area of an indoor...
Defining Air Duct Velocity
Mar 25, 2019 by Joe Hullebusch
The air duct velocity -- also known as air flow velocity -- is a measurement of the air that moves through your HVAC...
Defining Supply Air
Mar 25, 2019 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
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
Mar 25, 2019 by Joe Hullebusch
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
Mar 25, 2019 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
Value Engineering (VE) is an approach of analyzing and designing building systems -- such as HVAC -- to deliver the...
What is a Fan Coil Unit?
Mar 25, 2019 by Joe Hullebusch
A fan coil unit (FCU) is a standalone HVAC (heating, ventilation, and air conditioning) system that treats and/or...
What is a Linear Grille?
Mar 25, 2019 by Joe Hullebusch
Linear grilles are designed to cover sidewall, ceiling, and floor-based air diffuser/air supply and return systems. As...
Explaining Air Leakage
Mar 25, 2019 by Joe Hullebusch
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?
Mar 25, 2019 by Joe Hullebusch
A VAV -- i.e., Variable Air Volume -- HVAC (heating, ventilation, and air conditioning) system that supplies air at...
What is Air Throw?
Mar 25, 2019 by Joe Hullebusch
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
Mar 25, 2019 by Joe Hullebusch
The sole purpose of an HVAC (heating, ventilation, & air conditioning) system, air distribution -- also known as room...
What is a Subfloor?
Mar 25, 2019 by Joe Hullebusch
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?
Dec 23, 2015 by Joe Hullebusch
Underfloor Air Distribution (UFAD) is an air distribution strategy where heated or cooled conditioned air is...
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