Cooling degree days - Revision history

Designing Buildings at 07:50, 7 November 2020

2020-11-07T07:50:45Z

← Older revision		Revision as of 07:50, 7 November 2020
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	Cooling degree days (CDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represent the number of degrees and number of days that the outside air temperature at a specific location is higher than a specified base temperature (or balance point). This gives an indication of how much cooling will be required in the building.		Cooling degree days (CDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represent the number of degrees and number of days that the outside air temperature at a specific location is higher than a specified base temperature (or balance point). This gives an indication of how much cooling will be required in the building.

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	=== Related articles on Designing Buildings Wiki ===		=== Related articles on Designing Buildings Wiki ===
−	*Comfort in low energy buildings.	+
−	*Computational fluid dynamics.	+	* Comfort in low energy buildings.
−	*Energy targets.	+	* Computational fluid dynamics.
−	*Heat stress.	+	* Energy targets.
−	*Heating degree days.	+	* Heat stress.
−	*Passive building design.	+	* Heating degree days.
−	*Post occupancy evaluation.	+	* Passive building design.
−	*Solar gain.	+	* Post occupancy evaluation.
−	*Temperature.	+	* Solar gain.
−	*Thermal comfort.	+	* Temperature.
−	*Thermal indices.	+	* Thermal comfort.
−	*Thermal insulation.	+	* Thermal indices.
−	*Urban heat island effect.	+	* Thermal insulation.
		+	* Urban heat island effect.

	=== External references ===		=== External references ===
−	*[http://www.degreedays.net/ Degree Days] Net.
−	*Energy Lens, [http://www.energylens.com/articles/degree-days Degree Days – Handle with care].

−	[[~~Category~~:~~Standards_~~/~~_measurements~~]] [[Category:DCN_Standard]]	+	* [http://www.degreedays.net/ Degree Days] Net.
		+	* Energy Lens, [http://www.energylens.com/articles/degree-days Degree Days – Handle with care].
		+
		+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Standard]] [[Category:Standards_/_measurements]]

Designing Buildings at 05:37, 4 August 2014

2014-08-04T05:37:43Z

← Older revision		Revision as of 05:37, 4 August 2014
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−		+	Cooling degree days (CDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represent the number of degrees and number of days that the outside air temperature at a specific location is higher than a specified base temperature (or balance point). This gives an indication of how much cooling will be required in the building.
−	Cooling degree days (~~HDD~~) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represent the number of degrees and number of days that the outside air temperature at a specific location is higher than a specified base temperature (or balance point). This gives an indication of how much cooling will be required in the building.	+

	The base temperature of a building is the temperature above which it needs cooling, which will depend on the building type and use.		The base temperature of a building is the temperature above which it needs cooling, which will depend on the building type and use.
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	Websites such as [http://www.degreedays.net/ Degree Days] Net can be used to calculate cooling degree days for a given location and base temperature.		Websites such as [http://www.degreedays.net/ Degree Days] Net can be used to calculate cooling degree days for a given location and base temperature.

−	Data is also available to allow calculation of ‘heating degree days’ representing the number of degrees and days the outside temperature is below the base temperature and ‘growing degree days’, based on the temperature range within which plants will grow.	+	Data is also available to allow calculation of ‘heating degree days’ representing the number of degrees and days the outside temperature is below the base temperature and ‘growing degree days’, based on the temperature range within which plants will grow.

	Heating and cooling degree days can be used to help assess or compare different potential sites for development. They can also be used as a way of normalising weather between different sites, allowing comparison of the performance of different buildings, or for normalising weather between different years to assess the change in performance of a building.		Heating and cooling degree days can be used to help assess or compare different potential sites for development. They can also be used as a way of normalising weather between different sites, allowing comparison of the performance of different buildings, or for normalising weather between different years to assess the change in performance of a building.

−	However, despite being a very simple concept, they are difficult to use effectively in practice, and do not always provide an effective way of influencing design decisions. There can be difficulty separating out heating and cooling energy consumption from overall energy consumption, and heating and cooling requirements are influenced by other factors such as; other heat sources (including people, lighting, equipment and solar gain), thermal mass, thermal insulation and so on. In addition, heating and cooling ~~input tends~~ to be intermittent rather than continuous, and buildings are not necessarily always occupied.	+	However, despite being a very simple concept, they are difficult to use effectively in practice, and do not always provide an effective way of influencing design decisions. There can be difficulty separating out heating and cooling energy consumption from overall energy consumption, and heating and cooling requirements are influenced by other factors such as; other heat sources (including people, lighting, equipment and solar gain), thermal mass, thermal insulation and so on. In addition, heating and cooling inputs tend to be intermittent rather than continuous, and buildings are not necessarily always occupied.

−	It is possible to take account of these matters in calculations and through the use of sub-metering, but this can become a very complicated process, based on a deceptively simple indicator. The use of degree days should be treated with caution as part of a broader process of analysis ~~and assessment~~ providing a general indicator for order of magnitude assessments rather than accurate detailed comparisons.	+	It is possible to take account of these matters in calculations and through the use of sub-metering, but this can become a very complicated process, based on a deceptively simple indicator. The use of degree days should be treated with caution as part of a broader process of analysis, providing a general indicator for order of magnitude assessments rather than for accurate, detailed comparisons.

	= Find out more =		= Find out more =
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	*Thermal comfort.		*Thermal comfort.
	*Thermal indices.		*Thermal indices.
		+	*Thermal insulation.
	*Urban heat island effect.		*Urban heat island effect.

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	*Energy Lens, [http://www.energylens.com/articles/degree-days Degree Days – Handle with care].		*Energy Lens, [http://www.energylens.com/articles/degree-days Degree Days – Handle with care].

−	[[Category:Standards_/_measurements]]	+	[[Category:Standards_/_measurements]] [[Category:DCN_Standard]]

Designing Buildings: Created page with " Cooling degree days (HDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represe..."

2014-08-04T05:33:32Z

Created page with " Cooling degree days (HDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represe..."

New page

Cooling degree days (HDD) are used to give an indication of the effect of outside air temperature on building energy consumption during a specified period of time. They represent the number of degrees and number of days that the outside air temperature at a specific location is higher than a specified base temperature (or balance point). This gives an indication of how much cooling will be required in the building.

The base temperature of a building is the temperature above which it needs cooling, which will depend on the building type and use.

So for example, if the base temperature is 21 degrees, and the outside air temperature is 30 degrees for eight hours (one third of a day), then that represents 3 cooling degree days ((30-21) x 1/3 = 3).

Adding up the cooling degree days can give a weekly, monthly or annual figure.

Cooling degree days can be found for locations with publicly available meteorological data and so it is necessary to locate an accurate weather station, with good historical data close to the site being investigated, or in circumstances similar to the site being investigated. Weather station data such as that available from airports is often considered to be the highest quality.

Websites such as [http://www.degreedays.net/ Degree Days] Net can be used to calculate cooling degree days for a given location and base temperature.

Data is also available to allow calculation of ‘heating degree days’ representing the number of degrees and days the outside temperature is below the base temperature and ‘growing degree days’, based on the temperature range within which plants will grow.

Heating and cooling degree days can be used to help assess or compare different potential sites for development. They can also be used as a way of normalising weather between different sites, allowing comparison of the performance of different buildings, or for normalising weather between different years to assess the change in performance of a building.

However, despite being a very simple concept, they are difficult to use effectively in practice, and do not always provide an effective way of influencing design decisions. There can be difficulty separating out heating and cooling energy consumption from overall energy consumption, and heating and cooling requirements are influenced by other factors such as; other heat sources (including people, lighting, equipment and solar gain), thermal mass, thermal insulation and so on. In addition, heating and cooling input tends to be intermittent rather than continuous, and buildings are not necessarily always occupied.

It is possible to take account of these matters in calculations and through the use of sub-metering, but this can become a very complicated process, based on a deceptively simple indicator. The use of degree days should be treated with caution as part of a broader process of analysis and assessment providing a general indicator for order of magnitude assessments rather than accurate detailed comparisons.

= Find out more =

=== Related articles on Designing Buildings Wiki ===
*Comfort in low energy buildings.
*Computational fluid dynamics.
*Energy targets.
*Heat stress.
*Heating degree days.
*Passive building design.
*Post occupancy evaluation.
*Solar gain.
*Temperature.
*Thermal comfort.
*Thermal indices.
*Urban heat island effect.

=== External references ===
*[http://www.degreedays.net/ Degree Days] Net.
*Energy Lens, [http://www.energylens.com/articles/degree-days Degree Days – Handle with care].

[[Category:Standards_/_measurements]]