Night-time purging - Revision history

Designing Buildings at 09:56, 17 December 2021

2021-12-17T09:56:16Z

← Older revision		Revision as of 09:56, 17 December 2021
Line 25:		Line 25:
	NB Approved document F, Ventilation, defines 'purge ventilation' as, ‘…manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour. Purge ventilation may be provided by natural means (e.g. an openable window) or be mechanical means (e.g. a fan).		NB Approved document F, Ventilation, defines 'purge ventilation' as, ‘…manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour. Purge ventilation may be provided by natural means (e.g. an openable window) or be mechanical means (e.g. a fan).

−	= Related articles on Designing Buildings ~~Wiki.~~ =	+	= Related articles on Designing Buildings =

	* BREEAM Potential for natural ventilation.		* BREEAM Potential for natural ventilation.
Line 34:		Line 34:
	* Heat gain.		* Heat gain.
	* Passive building design.		* Passive building design.
−	* ~~Refrigerants.~~	+	* Purge ventilation.
−	* Reverberation time.	+
	* Stack effect.		* Stack effect.
	* Thermal comfort.		* Thermal comfort.

Designing Buildings at 08:30, 5 July 2021

2021-07-05T08:30:09Z

← Older revision		Revision as of 08:30, 5 July 2021
Line 39:		Line 39:
	* Thermal comfort.		* Thermal comfort.
	* Thermal mass.		* Thermal mass.
		+	* Types of ventilation.
	* Ventilation.		* Ventilation.

	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:Design]]		[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:Design]]

Designing Buildings at 12:44, 6 October 2020

2020-10-06T12:44:44Z

← Older revision		Revision as of 12:44, 6 October 2020
Line 41:		Line 41:
	* Ventilation.		* Ventilation.

−	[[Category:Design]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:Design]]

Editor at 17:33, 19 February 2019

2019-02-19T17:33:50Z

← Older revision		Revision as of 17:33, 19 February 2019
Line 25:		Line 25:
	NB Approved document F, Ventilation, defines 'purge ventilation' as, ‘…manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour. Purge ventilation may be provided by natural means (e.g. an openable window) or be mechanical means (e.g. a fan).		NB Approved document F, Ventilation, defines 'purge ventilation' as, ‘…manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour. Purge ventilation may be provided by natural means (e.g. an openable window) or be mechanical means (e.g. a fan).

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

	* BREEAM Potential for natural ventilation.		* BREEAM Potential for natural ventilation.
Line 34:		Line 32:
	* Chiller unit.		* Chiller unit.
	* Cooling.		* Cooling.
		+	* Heat gain.
	* Passive building design.		* Passive building design.
	* Refrigerants.		* Refrigerants.

Designing Buildings at 14:08, 26 March 2018

2018-03-26T14:08:57Z

← Older revision		Revision as of 14:08, 26 March 2018
Line 1:		Line 1:
−
	It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains, such as solar gain, people and equipment. This cooling is sometimes referred to as comfort cooling.		It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains, such as solar gain, people and equipment. This cooling is sometimes referred to as comfort cooling.

Line 13:		Line 12:

	Night-time purging can be passive, active or hybrid:		Night-time purging can be passive, active or hybrid:
−	*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove warm internal air, and in so doing, remove heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.	+
−	*Active systems use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems.	+	* Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove warm internal air, and in so doing, remove heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.
−	*Hybrid systems may only activate fan assistance when natural ventilation is insufficient.	+	* Active systems use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems.
		+	* Hybrid systems may only activate fan assistance when natural ventilation is insufficient.

	The thermodynamics of night-time cooling is extremely complicated and requires careful analysis.		The thermodynamics of night-time cooling is extremely complicated and requires careful analysis.
Line 28:		Line 28:

	=== Related articles on Designing Buildings Wiki. ===		=== Related articles on Designing Buildings Wiki. ===
−	*Building management systems.	+
−	*Chilled beam.	+	* BREEAM Potential for natural ventilation.
−	*Chiller unit.	+	* Building management systems.
−	*Cooling.	+	* Chilled beam.
−	*Passive building design.	+	* Chiller unit.
−	*Refrigerants.	+	* Cooling.
−	*Reverberation time.	+	* Passive building design.
−	*Stack effect.	+	* Refrigerants.
−	*Thermal comfort.	+	* Reverberation time.
−	*Thermal mass.	+	* Stack effect.
−	*Ventilation.	+	* Thermal comfort.
		+	* Thermal mass.
		+	* Ventilation.

	[[Category:Design]]		[[Category:Design]]

Designing Buildings at 07:51, 1 July 2015

2015-07-01T07:51:49Z

← Older revision		Revision as of 07:51, 1 July 2015
Line 14:		Line 14:
	Night-time purging can be passive, active or hybrid:		Night-time purging can be passive, active or hybrid:
	*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove warm internal air, and in so doing, remove heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.		*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove warm internal air, and in so doing, remove heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.
−	*Active systems use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems.	+	*Active systems use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems.
	*Hybrid systems may only activate fan assistance when natural ventilation is insufficient.		*Hybrid systems may only activate fan assistance when natural ventilation is insufficient.

−	The thermodynamics of night-time cooling is extremely complicated and requires careful analysis.	+	The thermodynamics of night-time cooling is extremely complicated and requires careful analysis.

	Correct operation may require staff training and fine tuning after occupation to ensure that the process is performing as expected. Careful control is required to ensure the correct level of cooling is provided. Building management systems (BMS) can use information about external and internal conditions to determine the level of cooling required and to activate systems.		Correct operation may require staff training and fine tuning after occupation to ensure that the process is performing as expected. Careful control is required to ensure the correct level of cooling is provided. Building management systems (BMS) can use information about external and internal conditions to determine the level of cooling required and to activate systems.

	NB it is important in the first instance that heat loads are minimised, for example by providing shading to reduce solar gain.		NB it is important in the first instance that heat loads are minimised, for example by providing shading to reduce solar gain.
		+
		+	NB Approved document F, Ventilation, defines 'purge ventilation' as, ‘…manually controlled ventilation of rooms or spaces at a relatively high rate to rapidly dilute pollutants and/or water vapour. Purge ventilation may be provided by natural means (e.g. an openable window) or be mechanical means (e.g. a fan).

	= Find out more =		= Find out more =

Designing Buildings at 10:22, 3 November 2014

2014-11-03T10:22:35Z

← Older revision		Revision as of 10:22, 3 November 2014
Line 1:		Line 1:

		+	It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains, such as solar gain, people and equipment. This cooling is sometimes referred to as comfort cooling.

−	It can be ~~necessary to provide cooling~~ to buildings ~~during warm weather~~, or ~~where there are significant thermal gains~~ such as ~~solar gain~~, ~~people~~ and ~~equipment~~. ~~This cooling is sometimes referred~~ to ~~as comfort cooling~~.	+	Thermal mass can be used to help cool buildings, or to reduce the need for active cooling systems such as heating, ventilation and air conditioning (HVAC) systems. Thermal mass describes the ability of a material to absorb, store and release heat energy. It can be used to store high thermal loads by absorbing heat during warm conditions, to be released when conditions are cooler. This can be beneficial both during the summer and the winter.

−	~~Thermal mass can be used to help cool buildings~~, or ~~to reduce~~ the ~~need for active cooling systems such as heating, ventilation and air conditioning (HVAC) systems. Thermal~~ mass ~~is the ability~~ of a ~~material~~ to absorb, ~~store~~ and ~~release~~ heat ~~energy. It can be used~~ to ~~store high~~ thermal ~~loads by absorbing heat during warm conditions, to be released when conditions are cooler~~. ~~This can be beneficial both~~ during the ~~summer and the winter~~.	+	Night-time cooling, or night-time purging uses the thermal mass of a building to absorb heat gains during the day, then cools the mass at night using external air and discharging accumulated heat to the outside so the temperature of the thermal mass is lowered ready for the next day. In the UK this reduces internal temperature rises during the day by around 3 to 6°C.

−	Night-time cooling~~, or night-time purging uses~~ the thermal mass of a building to ~~absorb heat gains during the day~~, ~~then cooling the~~ mass at night ~~with~~ cool ~~external~~ air ~~and discharging accumulated heat~~ to the ~~outside so~~ the ~~temperature of the thermal~~ mass ~~is lowered ready for the next day. This reduces~~ internal ~~temperature rises during the day, in the UK by around 3 to 6°C~~.	+	Night-time cooling requires that the construction of the building includes significant thermal mass which is exposed both to the occupied spaces of the building and to ventilation paths (either directly, or by indirect convection). This can mean that buildings have exposed concrete floor slabs, exposed brick walls, no carpets, no suspended ceilings and so on. Thermal mass for night-time cooling is most efficient in horizontal surfaces, in particular floors, as cool ventilation air will tend to fall to the floor level. NB the exposed mass can cause acoustic issues with high internal reverberation.

−	Night-time cooling requires that the construction of the building includes significant thermal mass which is exposed both to the occupied spaces of the buildings and to ventilation paths (either directly, or by indirect convection). This can mean that buildings have exposed concrete floor slabs, exposed brick walls, no carpets or suspended ceilings and so on. Thermal mass for night-time cooling is most efficient in horizontal surfaces, in particular floors, as cool ventilation air will tend to fall to the floor level. This exposed mass can cause acoustic issues with in high internal reverberation.	+	Night-time cooling is particularly effective in climates with a large diurnal temperature range (an absolute minimum of 5°C), where external air temperatures are too high to provide adequate natural cooling during the day, but where night-time temperatures are low enough to ‘pre-cool’ the building ready for the next day. NB Diurnal temperature differences may be lower in urban environments than rural environments.
−		+
−	Night-time cooling is particularly effective in climates with a large diurnal temperature range (an absolute minimum of 5°C), where external air temperatures are too high to provide adequate natural cooling during the day, but where night-time temperatures are low enough to ‘pre-cool’ the building ready for the next day. NB Diurnal temperature differences may be lower in urban than rural environments.	+

	It is also best suited to buildings are occupied during the day, but unoccupied at night.		It is also best suited to buildings are occupied during the day, but unoccupied at night.

−	Night-time purging can be passive, or active:	+	Night-time purging can be passive, active or hybrid:
−	*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove ~~stale~~ internal air, and in so doing, ~~removing~~ heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.	+	*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove warm internal air, and in so doing, remove heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.
−	*Active systems ~~can~~ use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full ~~HVAC systems. Alternatively, it can be used to reduce the loads on~~ HVAC systems.	+	*Active systems use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems.
−		+	*Hybrid systems may only activate fan assistance when natural ventilation is insufficient.
−	Hybrid systems may only activate fan assistance when natural ventilation is insufficient.	+

−	The thermodynamics of night-time cooling is extremely complicated and requires careful analysis~~. Correct operation may require staff training and fine tuning after occupation to ensure that the process is performing as expected~~.	+	The thermodynamics of night-time cooling is extremely complicated and requires careful analysis.

−	Careful control is required to ensure the correct level of cooling is provided. Building management systems (BMS) information about external and internal conditions ~~can be used~~ to determine the level of cooling required.	+	Correct operation may require staff training and fine tuning after occupation to ensure that the process is performing as expected. Careful control is required to ensure the correct level of cooling is provided. Building management systems (BMS) can use information about external and internal conditions to determine the level of cooling required and to activate systems.

	NB it is important in the first instance that heat loads are minimised, for example by providing shading to reduce solar gain.		NB it is important in the first instance that heat loads are minimised, for example by providing shading to reduce solar gain.
Line 32:		Line 30:
	*Chiller unit.		*Chiller unit.
	*Cooling.		*Cooling.
		+	*Passive building design.
	*Refrigerants.		*Refrigerants.
		+	*Reverberation time.
	*Stack effect.		*Stack effect.
	*Thermal comfort.		*Thermal comfort.

Designing Buildings: Created page with " It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains such as solar gain, people and equipment. This cooling is ..."

2014-11-03T10:15:20Z

Created page with " It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains such as solar gain, people and equipment. This cooling is ..."

New page

It can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains such as solar gain, people and equipment. This cooling is sometimes referred to as comfort cooling.

Thermal mass can be used to help cool buildings, or to reduce the need for active cooling systems such as heating, ventilation and air conditioning (HVAC) systems. Thermal mass is the ability of a material to absorb, store and release heat energy. It can be used to store high thermal loads by absorbing heat during warm conditions, to be released when conditions are cooler. This can be beneficial both during the summer and the winter.

Night-time cooling, or night-time purging uses the thermal mass of a building to absorb heat gains during the day, then cooling the mass at night with cool external air and discharging accumulated heat to the outside so the temperature of the thermal mass is lowered ready for the next day. This reduces internal temperature rises during the day, in the UK by around 3 to 6°C.

Night-time cooling requires that the construction of the building includes significant thermal mass which is exposed both to the occupied spaces of the buildings and to ventilation paths (either directly, or by indirect convection). This can mean that buildings have exposed concrete floor slabs, exposed brick walls, no carpets or suspended ceilings and so on. Thermal mass for night-time cooling is most efficient in horizontal surfaces, in particular floors, as cool ventilation air will tend to fall to the floor level. This exposed mass can cause acoustic issues with in high internal reverberation.

Night-time cooling is particularly effective in climates with a large diurnal temperature range (an absolute minimum of 5°C), where external air temperatures are too high to provide adequate natural cooling during the day, but where night-time temperatures are low enough to ‘pre-cool’ the building ready for the next day. NB Diurnal temperature differences may be lower in urban than rural environments.

It is also best suited to buildings are occupied during the day, but unoccupied at night.

Night-time purging can be passive, or active:
*Passive systems rely on passive or natural ventilation to supply fresh outside air into the building and remove stale internal air, and in so doing, removing heat from the thermal mass. Natural ventilation can be wind driven or buoyancy driven. Buoyancy-driven stack ventilation can be particularly effective as a passive mechanism for night-time purging as this is generally the time of day when the difference between the internal and external temperature is at is greatest and so the stack effect is at its strongest. Passive systems have very low operational and maintenance costs. However, they require open air pathways within the building, which can be a security or privacy issue, and natural ventilation may not be possible because of local air quality or noise issues.
*Active systems can use fan assistance to help drive air across the thermal mass, for example by ventilating floor voids. Active systems can be more targeted and controllable than natural systems, and air duct sizes can be smaller. Fan operation consumes energy, but this will tend to be less than full HVAC systems. Alternatively, it can be used to reduce the loads on HVAC systems.

Hybrid systems may only activate fan assistance when natural ventilation is insufficient.

The thermodynamics of night-time cooling is extremely complicated and requires careful analysis. Correct operation may require staff training and fine tuning after occupation to ensure that the process is performing as expected.

Careful control is required to ensure the correct level of cooling is provided. Building management systems (BMS) information about external and internal conditions can be used to determine the level of cooling required.

NB it is important in the first instance that heat loads are minimised, for example by providing shading to reduce solar gain.

= Find out more =

=== Related articles on Designing Buildings Wiki. ===
*Building management systems.
*Chilled beam.
*Chiller unit.
*Cooling.
*Refrigerants.
*Stack effect.
*Thermal comfort.
*Thermal mass.
*Ventilation.

[[Category:Design]]