UFAD Glossary

What is Plenum in HVAC?

A plenum in heating, ventilation, and air conditioning (HVAC) systems is a box that connects to the HVAC system. It has...

Defining HVAC Load

The HVAC load is a calculation that determines the building’s heating and cooling requirements. Knowing the HVAC load...

Defining Return Air

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?

In terms of HVAC systems, static pressure is the resistance against the air flow. Static pressure can emanate from a...

What is VOC?

VOCs -- i.e., volatile organic compounds -- are chemicals with molecules that can evaporate very quickly when exposed...

Explaining Thermostatic Controls

Thermostatic controls are HVAC controls that let end-users control their heating and cooling by setting the temperature...

LEED Definition

LEED is the acronym for the Leadership in Energy and Environmental Design certification. In terms of evaluating and...

What is WELL?

The WELL Building Standard is administered by the International WELL Building Institute (IWBI) to assess, score, and...

What is a Building Automation System?

A building automation system is a network of computers and devices that allow building owners and managers to digitally...

Explaining CFM HVAC

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?

In skin-load dominated buildings, energy usage is mostly influenced by the impact of the outside climate on the...

Explaining Sound Transmission Class

The sound transmission class (STC) is an integer rating for measuring and classifying how well a building wall or...

Explaining BAS HVAC

BAS HVAC refers to the systems necessary for connecting your HVAC system to your wider building automation system...

What is a Smart HVAC?

A smart HVAC (heating, ventilation, and air conditioning) system leverages networked HVAC components and other...

What is AHU?

‘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)

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?

Stratified air -- also known as thermal stratification -- occurs when cool, dense air sinks while the warm and thin air...

What are Diffuser Grilles?

Diffuser grilles are the outer frames you can use to enclose your variable air volume (VAV) or air supply diffusers....

Explaining Environmental Controls

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?

In HVAC systems, the air supply diffuser is a device that delivers and ventilates conditioned air in an area, mixes...

What is Perimeter Heating?

Perimeter heating is a method of distributing warm air through ducts installed in the surrounding area of an indoor...

Defining Air Duct Velocity

The air duct velocity -- also known as air flow velocity -- is a measurement of the air that moves through your HVAC...

Defining Supply Air

(Source: John Wiley & Sons, Best Practices Guide to Residential Construction - 2006) The supply air is the outside air...
1 min read

What is a Chilled Beam?

(Source: ACHR News) Chilled beam systems are a type of HVAC system that omits fans in favor of using fin-and-tube heat...

Slab-to-Slab Height

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

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?

Value Engineering (VE) is an approach of analyzing and designing building systems -- such as HVAC -- to deliver the...

What is a Fan Coil Unit?

A fan coil unit (FCU) is a standalone HVAC (heating, ventilation, and air conditioning) system that treats and/or...

What is a Linear Grille?

Linear grilles are designed to cover sidewall, ceiling, and floor-based air diffuser/air supply and return systems. As...

Explaining Air Leakage

In terms of HVAC systems, air leakage is when outside air penetrates your home or building via cracks, holes, or other...

What is VAV HVAC?

A VAV -- i.e., Variable Air Volume -- HVAC (heating, ventilation, and air conditioning) system that supplies air at...

What is Air Throw?

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

The sole purpose of an HVAC (heating, ventilation, & air conditioning) system, air distribution -- also known as room...

What is a Subfloor?

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?

Underfloor Air Distribution (UFAD) is an air distribution strategy where heated or cooled conditioned air is...

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