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Trevor: /* Relationship between SAP, energy costs, energy consumption and CO2 emissions */

2022-09-16T11:36:32Z

‎Relationship between SAP, energy costs, energy consumption and CO2 emissions

Trevor: /* Relationship between SAP, energy costs, energy consumption and CO2 emissions */

2019-12-02T14:11:07Z

‎Relationship between SAP, energy costs, energy consumption and CO2 emissions

Trevor at 14:09, 2 December 2019

2019-12-02T14:09:57Z

Trevor at 14:08, 2 December 2019

2019-12-02T14:08:01Z

Trevor at 14:02, 2 December 2019

2019-12-02T14:02:28Z

Trevor at 13:36, 2 December 2019

2019-12-02T13:36:42Z

Trevor at 13:15, 2 December 2019

2019-12-02T13:15:48Z

Trevor at 12:21, 2 December 2019

2019-12-02T12:21:44Z

Trevor at 12:00, 2 December 2019

2019-12-02T12:00:04Z

Trevor at 11:52, 2 December 2019

2019-12-02T11:52:17Z

@@ Line 19: / Line 19: @@
 ==Relationship between SAP, energy costs, energy consumption and CO<sub>2</sub> emissions==
-A convenient relationship between SAP rating and household expenditure on energy … and by extension, the households' energy consumption and CO<sub>2</sub> emissions … was required. The data set from [https://www.eagacharitabletrust.org/app/uploads/2016/03/finaleagactreport_saptargets_finalversion.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce but never eliminate the need to purchase energy i.e. the law of diminishing returns
+A convenient relationship between SAP rating and household expenditure on energy … and by extension, the households' energy consumption and CO<sub>2</sub> emissions … was required. The data set from Appendix 8 of [https://www.fuelpovertylibrary.info/sites/default/files/EAGA40%20%282006%29%20REPORT%20SAP%20targets%20and%20affordability%20in%20Social%20Housing.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce but never eliminate the need to purchase energy i.e. the law of diminishing returns
 [[File:SAP to cost.png|frameless|left|Cost correlation]]<br style="clear:both;" />

@@ Line 19: / Line 19: @@
 ==Relationship between SAP, energy costs, energy consumption and CO<sub>2</sub> emissions==
-A convenient relationship between SAP rating and household expenditure on energy … and by extension, the Household's energy consumption and CO<sub>2</sub> emissions was required. The data set from [https://www.eagacharitabletrust.org/app/uploads/2016/03/finaleagactreport_saptargets_finalversion.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce but never eliminate the need to purchase energy i.e. the law of diminishing returns
+A convenient relationship between SAP rating and household expenditure on energy … and by extension, the households' energy consumption and CO<sub>2</sub> emissions … was required. The data set from [https://www.eagacharitabletrust.org/app/uploads/2016/03/finaleagactreport_saptargets_finalversion.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce but never eliminate the need to purchase energy i.e. the law of diminishing returns
 [[File:SAP to cost.png|frameless|left|Cost correlation]]<br style="clear:both;" />

@@ Line 15: / Line 15: @@
 [[File:SAP correlation.png|frameless|Correlation]]
-There is considerable scatter in the data. Some of the lowest rated properties would benefit greatly from insulation, on the other hand mid-range rated houses may be old stock that have already been insulated to a good standard - or new houses that haven't been improved. The correlation between SAP values is positive, that is, the more energy efficient the house is to begin with, the higher the final achievable value. This relationship is subject to diminishing returns since an adequately insulated house can only be improved so far by further insulation, whereas an old and poorly insulated property has great scope for improvement in both absolute and percentage terms yet still not achieve the highest score even after all the recommended improvements. The thinner black trend line is the 'best-fit' to the data points and the bolder, red 45° line represents the current situation. The ''GAP'' between the rad and black lines may be regarded as the realistic potential for improvement in SAP rating
+There is considerable scatter in the data. Some of the lowest rated properties would benefit greatly from insulation, on the other hand mid-range rated houses may be old stock that have already been insulated to a good standard - or new houses that haven't been improved. The correlation between SAP values is positive, that is, the more energy efficient the house is to begin with, the higher the final achievable value. This relationship is subject to diminishing returns since an adequately insulated house can only be improved so far by further insulation, whereas an old and poorly insulated property has great scope for improvement in both absolute and percentage terms yet still not achieve the highest score even after all the recommended improvements. The thinner black trend line is the 'best-fit' to the data points and the bolder, red 45° line represents the current situation. The ''GAP'' between the red and black lines may be regarded as the realistic potential for improvement in SAP rating
 ==Relationship between SAP, energy costs, energy consumption and CO<sub>2</sub> emissions==

@@ Line 1: / Line 1: @@
 == Case study - 92 properties in SK31 ==
-Energy performance certificates (EPC) are a legal requirement when properties are built, sold or rented in the UK and the information is in the public domain. FLUKE has made a case study of 92 properties in the English East Midlands, ordnance survey grid area SK31. The housing stock consisted of a mixture older Victorian and early 20th century terraced housing and some more modern, estate built houses. (The data are anonymised and the grid area covers 100 square kilometres; this ''should'' provide adequate data protection to any individual householder). An EPC is issued following a detailed survey of the property and contains much useful information. This case study mainly focusses on the Standard Assessment Procedure (SAP) scores for the '''current''' and '''potential'''
+Energy performance certificates (EPC) are a legal requirement when properties are built, sold or rented in the UK and the information is in the public domain. FLUKE has made a case study of 92 properties in the East Midlands, England, ordnance survey grid area SK31. The housing stock consists of a mixture of older Victorian and early 20th century terraced housing and some more modern, estate built houses. (The data are anonymised and given the grid area covers 100 square kilometres; this ''should'' provide adequate data protection to any individual householder). An EPC is issued following a detailed survey of the property and contains much useful information. This case study mainly focusses on the Standard Assessment Procedure (SAP) scores for the '''current''' and '''potential'''
 energy efficiency ratings. The latter score indicates the potential improvement in efficiency that might be achieved, if all the energy-conserving measures including insulation, low energy lighting, solar water heating etc. recommended in the report were indeed carried out. The comparison between these 'before' and 'after' SAP rating figures provides a simple method for assessing the potential improvement achievable if the entire housing stock were renovated to all the recommended measures in the EPC.
@@ Line 11: / Line 11: @@
 [[File:SAP histogram potential.png|frameless|Potential]]
-Naturally, the distribution shifts to the (more energy-efficient) right, when the energy saving measures are implemented. Another way to view the data is to correlate the SAP ratings before and after improvements:
+As would be expected, when energy efficiency is improved the distribution shifts to the right hand side of the histogram, as energy saving measures are implemented. A more detailed way to view the data at the level of individual properties, is to correlate the SAP ratings before and after improvements:
 [[File:SAP correlation.png|frameless|Correlation]]

@@ Line 19: / Line 19: @@
 ==Relationship between SAP, energy costs, energy consumption and CO<sub>2</sub> emissions==
-A convenient relationship between SAP rating and household expenditure on energy … and by extension, the Household's energy consumption and CO<sub>2</sub> emissions was required. The data set from [https://www.eagacharitabletrust.org/app/uploads/2016/03/finaleagactreport_saptargets_finalversion.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce bit never eliminate the need to purchase energy i.e. the law of diminishing returns
+A convenient relationship between SAP rating and household expenditure on energy … and by extension, the Household's energy consumption and CO<sub>2</sub> emissions was required. The data set from [https://www.eagacharitabletrust.org/app/uploads/2016/03/finaleagactreport_saptargets_finalversion.pdf EAG Charitable Trust] was used to produce the following correlation and trendline. The exponential equation appears to be reasonable fit and the semi-empirical form can be justified from the observation that improvements in insulation and other energy-saving measures will reduce but never eliminate the need to purchase energy i.e. the law of diminishing returns
-[[File:SAP to cost.png|frameless|left|Cost correlation]]
+[[File:SAP to cost.png|frameless|left|Cost correlation]]<br style="clear:both;" />
-The final step is to tabulate the results using the two correlations. First assign mid-point SAP values to catgory bands: B=86, C=74.5, D=61.5, E=46.5 F=29.5, G=10.5. Use the cost correlation to convert SAP to current cost and a combination of both correlations to calculate the potential cost (after energy saving measures). Then weight these costs to take into account the percentage of houses in each EPC band and compute the weighted saving.
+The final step is to tabulate the results, making use of the two correlations. First assign mid-point SAP values to category bands: B=86, C=74.5, D=61.5, E=46.5 F=29.5, G=10.5. Use the cost correlation to convert SAP to current cost and a combination of both correlations to calculate the potential cost (after energy saving measures). Then weight these costs to take into account the percentage of houses in each EPC band and compute the weighted saving.
 {| class="wikitable"
@@ Line 29: / Line 29: @@
 ! Band !! % in band !! Current !! Weighted current !! Potential !! Weighted potential !! Weighted saving
 |-
-| G || 9% || £1,753 || £152 || £802 || £70|| £83
+| G || 9% || £1,753 || £152 || £802 || £70|| £82
 |-
 | F || 20% || £1,315 || £257 || £727 || £142 || £115
@@ Line 43: / Line 43: @@
 | TOTALS || 100% || || £1,005 ||  || £657 || £348
 |}

@@ Line 23: / Line 23: @@
 [[File:SAP to cost.png|frameless|left|Cost correlation]]
-The final step is to tabulate the results using the two correlations
+The final step is to tabulate the results using the two correlations. First assign mid-point SAP values to catgory bands: B=86, C=74.5, D=61.5, E=46.5 F=29.5, G=10.5. Use the cost correlation to convert SAP to current cost and a combination of both correlations to calculate the potential cost (after energy saving measures). Then weight these costs to take into account the percentage of houses in each EPC band and compute the weighted saving.
 {| class="wikitable"
 |-
-! Header text !! Header text !! Header text !! Header text !! Header text !! Header text !! Header text
+! Band !! % in band !! Current !! Weighted current !! Potential !! Weighted potential !! Weighted saving
 |-
-| Example || Example || Example || Example || Example || Example || Example
+| G || 9% || £1,753 || £152 || £802 || £70|| £83
 |-
-| Example || Example || Example || Example || Example || Example || Example
+| F || 20% || £1,315 || £257 || £727 || £142 || £115
 |-
-| Example || Example || Example || Example || Example || Example || Example
+| E || 16% || £1,017 || £166 || £667 || £109 || £57
 |-
-| G || 9% || £1,753 || £152 || £802 || Example || Example
+| D || 42% || £811 || £344 || £617 || £262|| £82
 |-
-| F || 20% || £1,315 || £257 || £727 || Example || Example
+| C || 12% || £666 || £80 || £578 || £69 || £11
 |-
-| E || 16% || £1,017 || £166 || £667 || Example || Example
+| B || 1% || £560 || £6 || £545 || £6 || £0
 |-
-| D || 42% || £811 || £344 || £617 || Example || Example
+| TOTALS || 100% || || £1,005 ||  || £657 || £348
 |}

← Older revision		Revision as of 12:21, 2 December 2019
Line 6:		Line 6:
	== Histograms for the current and potential SAP ratings ==		== Histograms for the current and potential SAP ratings ==

−	The following two charts show the distribution of SAP ratings for the 92 houses	+	The following two charts show the distribution of SAP ratings for the 92 houses:
		+
		+	[[File:SAP histogram current.png\|frameless\|left\|Current]]
		+	[[File:SAP histogram potential.png\|frameless\|Potential]]
		+
		+	Naturally, the distribution shifts to the (more energy-efficient) right, when the energy saving measures are implemented. Another way to view the data is to correlate the SAP ratings before and after improvements:
		+
		+	[[File:SAP correlation.png\|frameless\|Correlation]]
		+
		+	There is considerable scatter in the data. Some of the lowest rated properties would benefit greatly from insulation, on the other hand mid-range rated houses may be old stock that have already been insulated to a good standard - or new houses that haven't been improved.
		+
		+	The bolder, 45° line represents the current situat

← Older revision		Revision as of 12:00, 2 December 2019
Line 5:		Line 5:

	== Histograms for the current and potential SAP ratings ==		== Histograms for the current and potential SAP ratings ==
		+
		+	The following two charts show the distribution of SAP ratings for the 92 houses