Variable air volume VAV - Revision history

Designing Buildings at 07:43, 8 August 2022

2022-08-08T07:43:30Z

← Older revision		Revision as of 07:43, 8 August 2022
Line 28:		Line 28:
	Ventilation in buildings is regulated by Part F of the building regulations.		Ventilation in buildings is regulated by Part F of the building regulations.

−	~~= Find out more =~~	+	= Related articles on Designing Buildings =
−		+
−	=== Related articles on Designing Buildings ~~Wiki ==~~=	+

	* Air conditioning.		* Air conditioning.

51.52.172.90 at 17:09, 1 December 2021

2021-12-01T17:09:42Z

← Older revision		Revision as of 17:09, 1 December 2021
Line 22:		Line 22:
	The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.		The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.

−	Where variations between spaces mean that some local heating is required in to maintain constant temperatures throughout a building, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic ~~that~~ providing a warm air supply from the air handling unit when there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.	+	Where variations between spaces mean that some local heating is required in to maintain constant temperatures throughout a building, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic than providing a warm air supply from the air handling unit when there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.

	In dual duct systems, both cool air and warm air ducts are provided.		In dual duct systems, both cool air and warm air ducts are provided.

Designing Buildings at 08:00, 16 October 2020

2020-10-16T08:00:08Z

← Older revision		Revision as of 08:00, 16 October 2020
Line 50:		Line 50:
	* Volume.		* Volume.

−	[[Category:~~Products_/_components~~]] [[Category:~~DCN_Product_Knowledge~~]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:Products_/_components]]

Editor at 15:37, 12 November 2018

2018-11-12T15:37:14Z

← Older revision		Revision as of 15:37, 12 November 2018
Line 1:		Line 1:
−
	Ventilation is necessary in buildings to remove ‘stale’ air and replace it with ‘fresh’ air:		Ventilation is necessary in buildings to remove ‘stale’ air and replace it with ‘fresh’ air:
−	*Helping to moderate internal temperatures.	+
−	*Replenishing oxygen.	+	* Helping to moderate internal temperatures.
−	*Reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods.	+	* Replenishing oxygen.
−	*Creating air movement, which improves the comfort of occupants.	+	* Reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods.
		+	* Creating air movement, which improves the comfort of occupants.

	Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).		Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).

	Within these systems, ventilation and temperature can be regulated either by:		Within these systems, ventilation and temperature can be regulated either by:
−	*Variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume, constant temperature VV-CT).
−	*Constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume, variable temperature CV-VT).
−	*Variable volume, variable temperature (VV-VT sometimes referred to as variable volume and temperature - VVT).

−	VAV ~~systems tend to provide closer control~~ of air temperature ~~than~~ CAV ~~systems and require lower fan speeds~~, as ~~a result of which they can use less energy~~ and ~~generate less noise~~.~~<br/>~~	+	* Variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume, constant temperature VV-CT).
		+	* Constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume, variable temperature CV-VT).
		+	* Variable volume, variable temperature (VV-VT sometimes referred to as variable volume and temperature - VVT).

−	~~In simple~~ VAV systems~~, air handling units (AHU) supply air through ductwork~~ to ~~spaces within the building, and the~~ temperature of ~~the spaces is moderated by adjusting the supply flow~~.~~<br/>~~	+	VAV systems tend to provide closer control of air temperature than CAV systems and require lower fan speeds, as a result of which they can use less energy and generate less noise.

−	In more complex systems, where spaces have different heating or cooling demands, there may be additional local control of the amount of air that enters each space. Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space. The damper must always remain partially open to allow some ‘fresh’ air into the space.~~<br/>~~	+	In simple VAV systems, air handling units (AHU) supply air through ductwork to spaces within the building, and the temperature of the spaces is moderated by adjusting the supply flow.
		+
		+	In more complex systems, where spaces have different heating or cooling demands, there may be additional local control of the amount of air that enters each space. Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space. The damper must always remain partially open to allow some ‘fresh’ air into the space.

	The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.		The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.

−	Where variations between spaces mean that some local heating is required in to maintain constant temperatures throughout a building, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit when there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.~~<br/>~~	+	Where variations between spaces mean that some local heating is required in to maintain constant temperatures throughout a building, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit when there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.

	In dual duct systems, both cool air and warm air ducts are provided.		In dual duct systems, both cool air and warm air ducts are provided.
Line 30:		Line 31:

	=== Related articles on Designing Buildings Wiki ===		=== Related articles on Designing Buildings Wiki ===
−	*Air conditioning.
−	*Building services.
−	*Chiller unit.
−	*Computational fluid dynamics.
−	*Constant air volume.
−	*Cross ventilation.
−	*Dew point.
−	*Humidity.
−	*Interstitial condensation.
−	*Mechanical ventilation.
−	*Natural ventilation.
−	*Passive building design.
−	*Solar chimney.
−	*Stack effect.
−	*Thermal comfort.
−	*Ventilation.

−	[[Category:Products_/_components]]	+	* Air conditioning.
		+	* Building services.
		+	* Chiller unit.
		+	* Computational fluid dynamics.
		+	* Constant air volume.
		+	* Cross ventilation.
		+	* Dew point.
		+	* Humidity.
		+	* Interstitial condensation.
		+	* Mechanical ventilation.
		+	* Natural ventilation.
		+	* Passive building design.
		+	* Solar chimney.
		+	* Stack effect.
		+	* Thermal comfort.
		+	* Ventilation.
		+	* Volume.
		+
		+	[[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]

Designing Buildings at 10:36, 17 October 2014

2014-10-17T10:36:49Z

← Older revision		Revision as of 10:36, 17 October 2014
Line 32:		Line 32:
	*Air conditioning.		*Air conditioning.
	*Building services.		*Building services.
		+	*Chiller unit.
	*Computational fluid dynamics.		*Computational fluid dynamics.
	*Constant air volume.		*Constant air volume.

Designing Buildings at 07:51, 13 October 2014

2014-10-13T07:51:46Z

← Older revision		Revision as of 07:51, 13 October 2014
Line 9:		Line 9:

	Within these systems, ventilation and temperature can be regulated either by:		Within these systems, ventilation and temperature can be regulated either by:
−	*Variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume, constant temperature VV-CT).	+	*Variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume, constant temperature VV-CT).
	*Constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume, variable temperature CV-VT).		*Constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume, variable temperature CV-VT).
	*Variable volume, variable temperature (VV-VT sometimes referred to as variable volume and temperature - VVT).		*Variable volume, variable temperature (VV-VT sometimes referred to as variable volume and temperature - VVT).
Line 33:		Line 33:
	*Building services.		*Building services.
	*Computational fluid dynamics.		*Computational fluid dynamics.
		+	*Constant air volume.
	*Cross ventilation.		*Cross ventilation.
	*Dew point.		*Dew point.

Designing Buildings at 09:12, 12 October 2014

2014-10-12T09:12:33Z

← Older revision		Revision as of 09:12, 12 October 2014
Line 4:		Line 4:
	*Replenishing oxygen.		*Replenishing oxygen.
	*Reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods.		*Reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods.
−	*Creating air movement which improves the comfort of occupants.	+	*Creating air movement, which improves the comfort of occupants.

	Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).		Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).

−	Within these systems, ventilation and temperature can be regulated either by ~~variable~~ air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume-constant temperature VV-CT) ~~or by constant~~ air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume-variable temperature CV-VT) .~~<br/>~~	+	Within these systems, ventilation and temperature can be regulated either by:
		+	*Variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume, constant temperature VV-CT).
		+	*Constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume, variable temperature CV-VT).
		+	*Variable volume, variable temperature (VV-VT sometimes referred to as variable volume and temperature - VVT).

−	~~Variable Volume-Variable Temperature~~ systems ~~(VV-VT sometimes referred~~ to ~~as variable volume and~~ temperature ~~- VVT)~~ can ~~also be provided~~.<br/>	+	VAV systems tend to provide closer control of air temperature than CAV systems and require lower fan speeds, as a result of which they can use less energy and generate less noise.<br/>

−	VAV systems ~~tend to provide closer control of~~ air ~~temperature than CAV systems and require lower fan speeds~~, ~~as a result which they can use less energy~~ and ~~generate less noise~~.<br/>	+	In simple VAV systems, air handling units (AHU) supply air through ductwork to spaces within the building, and the temperature of the spaces is moderated by adjusting the supply flow.<br/>

−	In ~~simple VAV~~ systems, ~~air handling units (AHU) supply air through ductwork to~~ spaces ~~within the building~~, ~~and~~ the ~~temperature~~ is ~~moderated~~ by ~~adjusting~~ the ~~supply flow~~.<br/>	+	In more complex systems, where spaces have different heating or cooling demands, there may be additional local control of the amount of air that enters each space. Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space. The damper must always remain partially open to allow some ‘fresh’ air into the space.<br/>

−	~~In more complex systems, where spaces have different heating or cooling demands, there may be additional local control of~~ the ~~amount of~~ air ~~that enters each space~~ (~~or 'zone'~~).~~<br/>~~	+	The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.

−	Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space. The damper must always remain partially open to allow some ‘fresh’ air into the space.<br/>	+	Where variations between spaces mean that some local heating is required in to maintain constant temperatures throughout a building, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit when there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.<br/>
−		+
−	The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.	+
−		+
−	Where variations mean that local heating is required in ~~some zones~~ to maintain a ~~constant temperature~~, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit ~~where~~ there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.<br/>	+

	In dual duct systems, both cool air and warm air ducts are provided.		In dual duct systems, both cool air and warm air ducts are provided.

Designing Buildings at 09:03, 12 October 2014

2014-10-12T09:03:49Z

← Older revision		Revision as of 09:03, 12 October 2014
Line 8:		Line 8:
	Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).		Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).

−	Within these systems, ventilation and temperature can be regulated either by variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume ~~of air supplied~~ varies (also known as ~~constant~~ volume-~~variable~~ temperature CV-VT) or by constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as ~~variable~~ volume-~~constant~~ temperature VV-CT).	+	Within these systems, ventilation and temperature can be regulated either by variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume varies (also known as variable volume-constant temperature VV-CT) or by constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as constant volume-variable temperature CV-VT) .<br/>

−	Variable Volume-Variable Temperature systems (VV-VT sometimes referred to as variable volume and temperature - VVT) can also be provided.	+	Variable Volume-Variable Temperature systems (VV-VT sometimes referred to as variable volume and temperature - VVT) can also be provided.<br/>

−	VAV systems tend to provide closer control of air temperature than CAV systems and lower fan speeds ~~and~~ as a result, use less energy and generate less noise).	+	VAV systems tend to provide closer control of air temperature than CAV systems and require lower fan speeds, as a result which they can use less energy and generate less noise.<br/>

−	In simple systems, air handling units (AHU) supply air through ductwork to spaces within the building, and the temperature is moderated by adjusting the supply flow.	+	In simple VAV systems, air handling units (AHU) supply air through ductwork to spaces within the building, and the temperature is moderated by adjusting the supply flow.<br/>

−	In more complex systems, where spaces have different ~~heat~~ or cooling demands, there may be local control of the amount of air that enters each space.	+	In more complex systems, where spaces have different heating or cooling demands, there may be additional local control of the amount of air that enters each space (or 'zone').<br/>

−	Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space ~~(or zone)~~. The damper must always remain partially open to allow some ‘fresh’ air into the space.	+	Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space. The damper must always remain partially open to allow some ‘fresh’ air into the space.<br/>

−	The fans in the air handling unit are ~~then~~ adjusted (variable frequency drive VFD) to control the air pressure in the ~~ducts~~. Refrigerant flow is ~~then~~ adjusted to ensure that the air temperature is constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air ~~in order~~ to reduce the cooling load. Where variations ~~between zones means~~ that local heating is required, ~~the~~ terminal ~~unit~~ may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit where there is only limited heating demand. Heat may be provided by ~~electric~~ elements or by hot water coils.	+	The fans in the air handling unit are adjusted (variable frequency drive VFD) to control the air pressure in the ductwork. Refrigerant flow is also adjusted to ensure that the air temperature remains constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air to reduce the cooling load.
		+
		+	Where variations mean that local heating is required in some zones to maintain a constant temperature, VAV terminal units may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit where there is only limited heating demand. Heat may be provided in VAV terminal units by electrical elements or by hot water coils.<br/>

	In dual duct systems, both cool air and warm air ducts are provided.		In dual duct systems, both cool air and warm air ducts are provided.

Designing Buildings: moved Variable air volume to Variable air volume VAV

2014-10-12T08:57:01Z

moved Variable air volume to Variable air volume VAV

← Older revision

Revision as of 08:57, 12 October 2014

Designing Buildings: Created page with " Ventilation is necessary in buildings to remove ‘stale’ air and replace it with ‘fresh’ air: Helping to moderate internal temperatures. Replenishing oxygen. *Reducing ..."

2014-10-12T08:56:52Z

Created page with " Ventilation is necessary in buildings to remove ‘stale’ air and replace it with ‘fresh’ air: *Helping to moderate internal temperatures. *Replenishing oxygen. *Reducing ..."

New page

Ventilation is necessary in buildings to remove ‘stale’ air and replace it with ‘fresh’ air:
*Helping to moderate internal temperatures.
*Replenishing oxygen.
*Reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods.
*Creating air movement which improves the comfort of occupants.

Very broadly, ventilation in buildings can be classified as ‘natural’ or ‘mechanical’. Mechanical ventilation systems can also include heating, cooling, humidity control and air filtration. These functions are often described collectively as HVAC (Heating Ventilation and Air Conditioning).

Within these systems, ventilation and temperature can be regulated either by variable air volume (VAV), in which the temperature of the supply air remains constant, but the volume of air supplied varies (also known as constant volume-variable temperature CV-VT) or by constant air volume (CAV) in which the volume of air supply remains constant, but the temperature varies (also known as variable volume-constant temperature VV-CT).

Variable Volume-Variable Temperature systems (VV-VT sometimes referred to as variable volume and temperature - VVT) can also be provided.

VAV systems tend to provide closer control of air temperature than CAV systems and lower fan speeds and as a result, use less energy and generate less noise).

In simple systems, air handling units (AHU) supply air through ductwork to spaces within the building, and the temperature is moderated by adjusting the supply flow.

In more complex systems, where spaces have different heat or cooling demands, there may be local control of the amount of air that enters each space.

Typically, cool air is supplied by an air handling unit, and thermostatically controlled dampers regulate the amount of air that enters each space (or zone). The damper must always remain partially open to allow some ‘fresh’ air into the space.

The fans in the air handling unit are then adjusted (variable frequency drive VFD) to control the air pressure in the ducts. Refrigerant flow is then adjusted to ensure that the air temperature is constant. VAV terminal units may include fans that re-circulate a proportion of internal air along with the ‘fresh’ supply air in order to reduce the cooling load. Where variations between zones means that local heating is required, the terminal unit may re-heat the supply air. Despite the apparent waste of re-heating previously cooled air, this can be more economic that providing a warm air supply from the air handling unit where there is only limited heating demand. Heat may be provided by electric elements or by hot water coils.

In dual duct systems, both cool air and warm air ducts are provided.

Ventilation in buildings is regulated by Part F of the building regulations.

= Find out more =

=== Related articles on Designing Buildings Wiki ===
*Air conditioning.
*Building services.
*Computational fluid dynamics.
*Cross ventilation.
*Dew point.
*Humidity.
*Interstitial condensation.
*Mechanical ventilation.
*Natural ventilation.
*Passive building design.
*Solar chimney.
*Stack effect.
*Thermal comfort.
*Ventilation.

[[Category:Products_/_components]]