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ENV-2D02 ENERGY CONSERVATION 2006

Handout 3

Lecture Notes:-

Section 9 Building Regulations

Please note – the logical position of this section would be before Energy Management, but since there are continual changes to them during the preparation of the handouts, this is included as Section 9 this year. If the situation becomes clearer , the regulations mat be taught before the Management Section.

Section 10. Electricity Conservation

N.K. Tovey ENV-2D02 Energy Conservation – 2006 Section 9 Building Regulations


CONTENTSPage

9. Building Regulations 42

9.1 Summary 429.2. Deficiencies in Earlier Building Regulations. 429.3 The 1994 Building Regulations 43

9.4 Building Regulations 2000 439.5. Effect of Construction Type (Built Form) on Energy Consumption 439.6 Improvements in 1994 and 2000 Regulations. 459.7 Current (2002) Regulations for buildings other than houses

Document L2.45

9.8 Main Differences of 2000 Regulations 459.9 The Draft 2005 Building Regulations due to come into force on 6 th

April 2006.46

9.9.1 Technical Changes 469.9.2. Compliance 46

9.10 A critique of the Standard Assessment Procedure SAP (1994) with different strategies:-

47

9.11 Other Problems in 1994 Regulations with comments on 2000 Regulations – where different.

47

9.12 General Procedure for using 2000 Regulations – Compliance Procedures

47

9.12.1 The Elemental Approach 479.12.2 The Target U-Value Approach 489.12.3 Carbon Index Method 48

9.13 The Standard Assessment Procedure - 2001. 489.14 SAP Rating for 2005 Regulations. 499.15 The Carbon Index Calculations (2000 Regulations). 499.16 The Dwelling Emission Rate (DER) 509.17 Supplementary Notes on U-values/heat Loss calculations 51

9.17.1 A simple way to assess a revised U-value. 519.17.2 Calculation of U-values for a floor 519.17.3 Energy Conservation - Savings Arising From Partial Heating of a Dwelling.

51

10. Electricity Conservation 54

10.1 Introduction 5410.2. Potential Growth in Electricity (excluding fuel switching). 5410.3 The Standby Problem 5410.4 Technical improvements to reduce electricity consumption 55

10.4.1 Power Factor Correction 5510.4.2 Kilowatts, kVA, kilovars 56

10.5 Controlling the demand for electricity 5610.5.1 Introduction 5610.5.2 Meeting the demand for electricity 5610.5.3 Shifting Demand 5810.5.4 Financial Incentives to shift demand 58

10.6 Other methods to reduce demand. 6110.7 Increase in electricity Consumption following Fuel Switching 61


9 BUILDING REGULATIONS

9.1 Summary

The current Building Regulations (2000) came into force on April 1st 2002 and replaced the 1994 regulations. The 1994 regulations were a noticeable improvement on previous regulations, and did attempt to address the issue of overall energy requirements. This concept was extended in the 2000 Regulations, but even these are deficient in many respects.

On 6th April 2006 the next revision of the Building Regulations (2005) come into force.

The section of the Building Regulations dealing with Energy Conservation is Section L, often referred to as Approved Document L “Conservation of Fuel and Power” (or ADL). In 2002, ADL became available on the WEB and is divided now into two sections L1 for domestic premises, and L2 for other buildings. Belatedly the 1994 Regulations were published on the WEB.

As a background, the following Table summarises the previous, current and the regulations which came into force in April 2002 together with those which are to come into force on 6th April 2006. However, the 2005 Building Regulations are still in Draft

Form, although few further changes are now expected as there has been extensive consultation.

In the 2005 regulations, the Approved Documents are further divided into ADL1a - for new dwellings, ADL1b for modifications to existing dwellings, ALD2a - for new non-domestic buildings, and ADL2b for modifications to existing non-domestic buildings. Dwellings are defined as individual household units – so the UEA student residences would come under ADL2a.

In the Energy White Paper (February 2003), the Government declared the aim of bringing forward the next revision of the Building Regulations to 2005 for implementation later that year or by 2006 to comply with EU legislation. Discussions on consultations on these new regulations began in early summer 2004.

To understand the latest regulations it is necessary to track the key changes that have taken place, particularly in the last 10 years.

Copies of all recent building regulations are available on the Course WEB Page.

TABLE 9.1 Summary Table of U-values for different Building Regulations1976 1985 1990 1994 2000 2005

U – Values W m-2 oC-1

SAP < 60 SAP > 60External Wall 1.0 0.6 0.45 0.45 0.35 0.45 0.35Roof 0.6 0.35 0.25 0.2 0.16 0.25 0.16Floor 1.0 0.6 0.45 0.35 0.25 0.45 0.25Windows not

specifiednot

specifiednot

specified3.0 2.0* 3.3 2.0

Windows as % of external walls equivalent to 17%

12 -

Windows as % of total floor areas - - 15 22.5 25 22.5 25%* 2.2 if the window frame is metal** In the 2005 regulations there is no compliance procedure based solely on U-Values. The specified U-Values are those to be used in the Target Emissions Rating for the dwelling.

9.2 Deficiencies in Earlier Building Regulations.

· Until the implementation of the 1994 Regulations in 1995, if double glazing was used, then area of windows could be doubled. There was thus little incentive to encourage double glazing and potential energy saving.

· Traditionally if double glazing was used, then requirements for walls/roof/floor could be relaxed provided that the overall loss does not exceed that of a house of same overall size and built to conform to the relevant Building Regulations. This is a Trade off of type 1.

· From 1985, it was possible to include incidental gains from appliance use/ solar gain etc. and it could be demonstrated that consumption in year was no greater than standard house, then regulations could be relaxed further.

· The 1994 and 2000 regulations do address problem of overall running costs, but continue to allow trade off. Thus if in 1994 Regulations, if triple glazing is used then window

area can be effectively increased by 50%. This was Type 2 trade off. In the latest Regulations, triple glazing or double glazing with low emissivity is required, and this type of trade of is no longer possible.

· If higher insulation standards are applied to walls then even more window area is permitted provided that the overall heat loss does not exceed that of a similarly sized house built to specified standards. This was effectively the statement of Compliance. In the 1994 Regulations this was considered by the Target – U Value method as an alternative to meeting the requirements for each individual fabric element.

· Traditionally, Building Regulations have been framed in a way for minimum compliance rather than to actively promote conservation. This is less of a the case in the 2000 regulations which came into force in April 2002. In the 2005 Regulations it appears that this has been tightened further.

· None of the Building Regulations specify a maximum ventilation rate, and with significant improvements to fabric

41


losses, ventilation losses are becoming proportionally more important in percentage terms.

9.3 The 1994 Regulations.

Prior to the 1994 Regulations, the energy conservation was primarily concerned with the “U-“ values of the different elements of the fabric (i.e. the walls, floor, roof, windows). There were opportunities in the regulations in the late 1990s to consider overall energy loss as an alternative means of satisfying the regulations, but there was little guidance on how this might be down, and implied that it had to be left to a competent person to do such calculations. The 1994 regulations saw some major changes over and above the normal changes to U-values etc. seen in previous versions. Not only were “U”- values improved, in some cases substantially, but a standard methodology was adopted for calculating overall energy requirements. This was known as the Standard Assessment Procedure or more commonly as the SAP Rating. To avoid confusion with the current regulations, the SAP Rating will be referred to as the SAP 1994 Rating

· Some of the key developments of the 1994 Regulations:-

· Single glazing can no longer be used routinely for domestic buildings (it could be used subject in trade-offs – see later).

· The glazed area can now be as high as 22.5% of floor area. This is 50% larger than the 1990 regulations, so though double glazing is now used 50% of the potential saving is lost because of the relative increased window area. It is true that solar gain would be increased slightly by larger windows, but the extra with double glazing does not outweigh the additional losses from an increased area.

· A SAP 1994 (or Standard Assessment Procedure) rating had to be computed for new dwellings. This was a crude index of how good the energy performance of a house was ranging from 0 for very bad to 100 for very good. Theoretically it is possible to achieve a rating of 115 although values over 100 were rare. The idea behind having a scale which could theoretically exceed 100, really meant that the buildings would have a higher rating than they deserved, and was probably to placate the Building Industry.

· In the 1994 Regulations, there is NO REQUIREMENT to reach a particular SAP, but requirements can be relaxed if SAP > 60. However, if a building had a SAP rating in excess of 80 – 84 (depending on building size), it would automatically satisfy the Building Regulations, even if the “U” – values were higher than those stipulated. Thus fitting a solar panel or a condensing boiler and it was possible to have less stringent insulation!!!!! The SAP 1994 Rating takes into account method of heating, and once again you can relax insulation if you have a more efficient heating system!!

· The SAP Rating system was supposed to be concerned with reduction of CO2, BUT THE METHOD OF ANALYSIS for determining the SAP 1994 Rating was (and still is in SAP 2001) solely USURPED BY MONETARY ISSUES leading to the rating giving potentially very misleading information.

9.4 Building Regulations 2000 (implemented 1st April 2002).

The current regulations (until 6th April 2006) in effect down play the relevance of the SAP Rating, although it is expected that these will still be computed. Details of the SAP 2001 (though published in late December 2001 did not come available until late January 2002.

The 2002 regulations see further reductions in U-Values for all key components. Indeed they are now approaching the technical limits with brick built buildings. The new regulations for glazing are particularly tight as triple glazing will normally be required or if not double glazing with ultra low emissivity.

There is however an increase in the allowable glazed area as a proportion of floor area to 25% (from 22.5% in 1994 and 15% in 1990). This does mean that if the actual percentage of glazed area is much less than this figure, then low performing windows can be used. It appears that designers are being given flexibility here – large areas of windows with low U-value windows or smaller areas with higher U-value.

The 2000 regulations are also quite demanding in the case of loft insulation as it is no longer possible to put boards down in a loft – for potential storage. Instead two layers should be installed – one lying between the joist and the other at right angles.

Unlike the 1994 regulations meeting a target SAP rating of 80 – 84 no longer applied, but there was a requirement to make a SAP 2001 calculation to provide some continuity with the previous rating scheme (particularly for those selling new houses.

Much of the SAP 2001 rating calculation remains the same as the SAP 1994 method, although there are some changes. An important different is that a completely new set of energy prices is included, as is the so called energy cost deflator which is now set as 1.05 as opposed to 0.96 in the 1994 Regulations. As with the 1994 regulations, the SAP Rating is really an attempt at an economic, rather than energy rating of the house. It attempts to include energy running costs in the calculation. This greatly increases complexity, and continues to create anomalies – see sections 9.5 onwards.

Table 9.2 shows the effect of the various regulations on energy consumption. In each case it is assumed that the overall shape of the house is identical and that the area of the windows is the same.

9.5. Effect of Construction Type (Built Form) on Energy Consumption

This section reviews variations in energy demand for different types of construction i.e. house/bungalow/flat. All built forms are assumed to have the same total floor areas of 98 sqm, with a plan area of 49 sqm in two storey buildings, and 98 sqm in a single one storey unit. The results are shown in Table 9.3

The plan shape is assumed to be square, giving a 7 m x 7m construction for a two storey house and a 9.8 m x 9.8 m for s single storey construction. It is assumed that all units have 15 sq m of window. The comparison is done for 2000 Regulations and also the 1976 regulations.

Note: the dimensions of the house are identical with those in the previous section.

42


TABLE 9.2 Comparison of Energy Consumption for a standard detached house 7m x 7m x 5 m high with 15 sq m of windows – at various ages and improvements

Heat losses in W 0C-1

Walls Windows Floor Roof Ventilation Totalpre-war unimproved 263 86 32 146 177 703pre-war loft insulation (25mm) 263 86 32 45 177 602pre-war loft insulation (50mm) 263 86 32 28 177 586pre-war loft insulation (100mm) 263 86 32 17 177 574pre-war loft insulation (100mm) + standard double glazing 263 43 32 17 115 469pre-war loft insulation (200mm) + triple glazing 263 30 32 9 88 422post-war unimproved 200 86 32 78 155 551post-war loft insulation (25mm) 200 86 32 39 155 512post-war loft insulation (50mm) 200 86 32 26 155 499post-war loft insulation (50mm) + cavity insulation 66 86 32 26 133 343post-war loft insulation (100mm) 200 86 32 16 155 488post-war loft insulation (100mm) + cavity insulation 66 86 32 16 133 332post-war loft insulation (100mm) + standard double glazing 200 43 32 16 106 397post-war loft insulation (100mm) + standard double glazing +

cavity insulation66 43 32 16 97 254

post-war loft insulation (200mm) + triple glazing + cavity insulation 66 30 32 9 88 2261960's Unimproved 125 86 32 78 155 4761960's loft insulation (25mm) 125 86 32 39 155 4371960's loft insulation (50mm) 125 86 32 26 155 4241960's loft insulation (50mm) + cavity insulation 50 86 32 26 133 3261960's loft insulation (100mm) 125 86 32 16 155 4131960's loft insulation (100mm) + cavity insulation 55 86 32 16 133 3211960's loft insulation (100mm) + standard double glazing 125 43 32 16 106 3221960's loft insulation (100mm) + standard double glazing +


1960's loft insulation (200mm) + triple glazing + cavity insulation 55 30 32 9 88 2151976 unimproved (includes 50 mm loft insulation) 125 86 32 26 133 4011976 cavity insulation 55 86 32 26 115 3141976 loft insulation (100mm) 125 86 32 16 133 3911976 loft insulation (100mm) + cavity insulation 55 86 32 16 115 3031976 loft insulation (100mm) + standard double glazing 125 43 32 16 106 3221976 loft insulation (100mm) + standard double glazing +


1976 loft insulation (200mm) + triple glazing + cavity insulation 55 30 32 9 88 2151985 unimproved (includes 100m loft insulation) 75 86 29 17 88 2951985 standard double glazing 75 43 29 17 88 2531985 standard double glazing + cavity insulation 56 43 29 17 88 2341985 loft insulation (200mm) + triple glazing + cavity insulation 56 30 29 9 88 2131990 unimproved (includes 150m loft insulation) 56 86 22 12 88 2641990 standard double glazing 56 43 22 12 88 2221990 loft insulation (200mm) + triple glazing 56 30 22 9 88 2061994 unimproved (includes 200m loft insulation + standard

double glazing56 45 17 12 88 219

2000 unimproved (includes 250m loft insulation + standard double glazing

44 30 12 8 88 182

Note: some improvements are not relevant. i.e. a house which already had double glazing could not have triple glazing fitted.

The figures for the new 2005 regulations will be similar to the 2000 regulations. The main difference lies in the fact that the U-values in earlier regulations were target values, and although areas of thermal bridging were to be minimised, there were no detailed check on this. In the latest regulations, the U-values are the area-weighted dwellings averages.

43


,

44

TABLE 9.3 Effects of Built Form on Energy Consumption

Roof Floor Wall Window Wall Window Total Vent. 2002 1976Losses Losses Area Area Losses Losses Losses Losses Total Losses Losses

detached house 7.8 12.3 125.0 15.0 43.8 30.0 93.8 88.4 182.3 465.8semi-detached house 7.8 12.3 105.0 15.0 36.8 30.0 86.8 88.4 175.3 445.8terraced house 7.8 12.3 55.0 15.0 19.3 30.0 69.3 88.4 157.8 395.8detached bungalow 15.7 24.5 84.0 15.0 29.4 30.0 99.6 88.4 188.0 503.2semi-detached bungalow 15.7 24.5 59.2 15.0 20.7 30.0 90.9 88.4 179.4 478.4bottom end flat - 24.5 59.2 15.0 20.7 30.0 75.2 88.4 163.7 419.6top end flat 15.7 - 59.2 15.0 20.7 30.0 66.4 88.4 154.9 380.4mid-storey end flat - - 59.2 15.0 20.7 30.0 50.7 88.4 139.2 321.6bottom centre flat - 24.5 34.5 15.0 12.1 30.0 66.6 88.4 155.0 394.9top centre flat 15.7 - 34.5 15.0 12.1 30.0 57.8 88.4 146.2 355.7mid-storey - - 34.5 15.0 12.1 30.0 42.1 88.4 130.5 296.9centre flat - - 34.5 15.0 12.1 30.0 42.1 88.4 130.5 296.9

Heat Losses in WoC-1 for different types of dwelling of same area and volume

9.6 Improvements in 1994 and 2000 Regulations.

· While they do not specify ventilation rates, they give advise on how to estimate ventilation rates.

· They make allowance for solar hot water heating if fitted.

· They include hot water requirements as well as space heating.

· They attempt to provide a rating for each house but there is no requirement to reach any particular value. In the 1994 Regulations achieving a SAP Rating of greater than approximately 80 (depending on house size), meant that Building Regulations were automatically satisfied i.e. Compliance could be achieved if the SAP rating was above a specified value. In 2000 Regulations, the SAP rating method for compliance with the Regulations has been dropped and replaced by a Carbon Index Rating.

As will be seen in section 9.11 there a numerous deficiencies in the SAP Rating System, but unfortunately the idea perpetuates even in the 2005 Regulations.

The 2000 Regulations for dwellings are available form the Energy Pages WEB links at :

www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/L1_cover.pdf

and www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/L1_main.pdf

The above sites are clones of the original and should thus avoid the problems associated with the continual moving of external sites.

9.7 Current (2002) Regulations for buildings other than houses Document L2.

In general the regulations for buildings other than single house dwellings have always been less stringent than for individual houses. However, as from the 2000 (2002 Edition), the U-values for all elements are identical with those in dwellings. The permitted glazed areas however are larger as show below.

Building Type Max: single-glazed window

area

Max. single glazed roof

light% of wall % of roof

Other Residential 30 20Shop, Office/ Assembly 40 20Industrial Storage/ Workshops

15 20

Like the Dwellings, there will now be a calculation method based on Carbon Dioxide Emission,

The Document L2 may be consulted directly from the Energy Courses WED Links pages or directly at:

www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/L2_cover.pdfand

www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/L2_main.pdf

9.8 Main Differences of 2000 Regulations

· Approved Document L has now been divided into 2 parts:-a) Approved Document L1 “Conservation of fuel and

power in dwellings”b) Approved Document L2 “Conservation of fuel and

power in other buildings”

· Effects of Boiler Seasonal Efficiency, particularly in respects of Hot Water provision are now included.

· The standards of fabric insulation have been improved, by setting lower standards and also changing methods for calculation.

· Lower U-values for windows have been set, although the area of glazing permitted has been increased slightly to provide extra design flexibility.

· Restrictions on Trade-offs have been placed particularly on extensions to existing buildings, although there does seem some extra flexibility with regard to the inclusion of trade-off between efficient boilers and U-values in the Elemental

http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/l1_cover.pdf






Method (see section 9.12.1. for a discussion about the Elemental approach).

· The SAP rating as a means of compliance has been dropped. This is a significant improvement. However, SAP ratings must still be completed to the 2001 procedures and notified to the Building Control Authority for New Buildings.

· The New Carbon Index Method replaces the SAP rating as a means of compliance. The concept of this is a significant improvement. However, the actual implementation is still not sending the correct message (see section 9.12.3 ).

· There are also several other smaller changes of detail on the precise methods for calculating some aspects of the analysis.

9.9 The Draft 2005 Building Regulations due to come into force on 6th April 2006.

The latest revision of the Building Regulations was brought forward and initially flagged in the Energy White Paper (2003). Part of this reason was the impending EU legislation which will require a significant change in the way Building Regulations are managed. In particular, there will shortly be the requirement for a Home Information Pack (HIP) which, it is planned, will give potential purchasers not only the design specification as afar as energy consumption is concerned, but also information on actual energy consumption. This will mean that each time a house changes hands a HIP must be produced, and that the information must be updated by a competent person at regular intervals. Thus a house sold twice, the second time say 10 years after the first will not be allowed to use the Energy information for the original HIP even if there have been no changes in the building.

The 2005 Regulations represent a much more substantive change in Regulations than anything previously apart from the changes introduced in 1994.

9.9.1 Technical Changes

There have been several changes in the way U-values are specified, and indeed shortly there will be a standard method produced by the Office of the Deputy Prime minister (ODPM) outlining how this is done. Some of the key issues are listed below – but for a more comprehensive discussion see:

· http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/ interim_adl1a_2006.pdf for new dwellings

· http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/ interim_adl1b_2006.pdf for existing dwellings

· http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/ interim_adl2a_2006.pdf for new non-domestic buildings

· http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/ interim_adl2b_2006.pdf for existing non-domestic buildings

· Issues such as thermal bridging will come much more to the forefront and it is the weighted average of such that must be considered rather than merely taking steps in design detail to avoid thermal bridging.

· Pressure testing of dwellings will become more common and in any development over a certain size, a minimum number of houses must be tested for air-leakage.

· U-value calculation of windows must taken into account the area of the frames

· Information on lighting use must be included

· Estimations of potential overheating in summer must be included.

· Shading issues relating to solar gain etc must be addressed

9.9.2. Compliance

Perhaps the biggest change is in the way compliance is achieved. There are now five separate Criteria which must be met (see the WEB links in section 9.9.1).

It was inevitable that a completely new set of criteria would be needed as it would have been impossible to carry the current method of compliance via the Carbon Index forward see section 9.15 for a discussion on the limitations of this method even in the current regulations.

· Criterion 1A Dwelling Emission Rating (DER) must be calculated taking due account of the U-values, the size, the types of heating etc using the Standard Assessment Procedure (SAP) – note this part of the SAP calculations are fine – it is the subsequent use of a SAP Rating which is nonsensical (see sections 9.10 – 9.12). The DER must be shown to be less than the Target Emission Rating (TER) which is computed with the same size of building and U-values meeting those in Table 9.1 Further details of this are summarised in section 9.16, however, for a detailed discussion you should consult the WEB link for new dwellings given in section 9.9.1. In addition details of the actual calculations may be found in:-

· http://www2.env.uea.ac.uk/gmmc/energy/ env2d02/pdf/Final_SAP2005_text.pdf for the main text

· http://www2.env.uea.ac.uk/gmmc/energy/ env2d02/pdf/Final_SAP2005_tables.pdf for the associated tables

· http://www2.env.uea.ac.uk/gmmc/energy/ env2d02/pdf/Final_SAP2005_worksheet.pdf for an example worksheet.

· Criterion 2 – limits on design flexibilityThe performance of the building must not be worse than a

given standard. In theory Criterion 1 gives considerable latitude in design – the old trade-off problem. For instance Criterion 1 could be satisfied by including renewable energy to offset a poor thermal insulation. However, in say 10 – 20 years time there is nothing to stop the renewable energy device from being stripped out and hence there would be an inferior building. This criterion attempts to limit this type of trade. Off – see pages 5 and 6 of the Draft Approved Document (WEB Link as in section 9.9.1).

· Criterion 3 – Limiting effects of solar overheatingThis criterion requires that the effects of overheating in summer must be assessed and suitable measures must be included to control such gain – e.g. avoiding excessive use of south facing windows, provision of suitable ventilation etc.

· Criterion 4 Quality of ConstructionWhen submitting plans for approval, all calculations are based on predicted performance. This criterion requires evidence of actual performance – e.g. changes arising from design modifications, quality of workmanship. Some of the requirements involve pressure testing the building to ensure they have achieved those used in the design specification.

· Criterion 5. Providing InformationThis criterion requires information on the maintenance and

operation of the building to be made available and eventually this will become art of the Home Information Pack

http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/Final_SAP2005_worksheet.pdf


http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/Final_SAP2005_tables.pdf


http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/Final_SAP2005_text.pdf

http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/Final_SAP2005_text.pdf

http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/interim_adl2b_2006.pdf


http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/interim_adl2a_2006.pdf






9.10 A critique of the Standard Assessment Procedure SAP (1994) with different strategies:-

The SAP Rating was initially an attempt to incorporate all the energy uses in a house and provide an index which may be used to illustrate how energy efficient a house is. This mechanics of the procedure is explained more fully in section 9.13

Some experimentation by Monahan (2002) and Turner (2003) suggest that many of the anomalies of the 1994 SAP method remain. Turner also noted that there were limitations when applying the procedures to existing houses, particularly when there were variable temperatures in different rooms.

Monahan, J. (2002) Msc Dissertation UEATurner, C. (2003) BSc Dissertation UEA

The following table shows typical changes in SAP Rating following specific changes as indicated. Because the SAP rating is essentially a monetary assessment, and because for some fuels (e.g. electricity, the standing charge is ignored, even when there is one), and others it is included, the SAP Rating can give misleading information. The new 2000 Regulations do nothing to rectify this situation.

Effective Changes in SAP rating with specified changes (based on 1994 regulations).

SAP changes byChange U-values by 10% 2 – 3Change window area by 10% 1 – 2change floor area by 10% 4 – 5change heating from mains gas to LPG (appears odd because there is little difference in overall energy consumption)

-15

change heating from condensing gas to inferior oil

+5 - 10!!!!!!!

Some of these seem to make a mockery of whole process.

The changes made in the 2000 Regulations are likely to change these effects little.

9.11 Other Problems in 1994 Regulations with comments on 2000 Regulations – where different.

· The SAP Rating Procedure adds considerable complexity to analysis procedure by trying to assess internal temperatures in a living room which is arbitrarily sized compared to rest of house. The effects of this compensation are fairly minimal anyway.

Though SAP Rating can no longer be used to demonstrate compliance of Thermal Performance in the 2000 Regulations, the calculations still must be done to satisfy the general Building Regulations.

· Only assumes a general heating level in house (one living and all other rooms standard).

· Requires a knowledge of hot water requirements which is based on floor area formula rather than occupancy

· Incidental gains also based on floor area rather than occupancy.

Problem - what is it realistic to do here as house may have different numbers of occupants at different times.

· Ultimately gives a rating which is economically based rather than energy based. Serious errors in message conveyed by rating can occur because of relative fuel price distortions.

e.g. fixed charge for gas included, but not electricity (oil does not have a fixed charge anyway).

· Consequence,a lower efficiency oil heating appliance will often give a higher SAP than an more efficient GAS system

CRAZY!! - regulations are supposed to be saving energy !!! - but it reflects the over emphasis on monetary values

· A more bizarre situation could arise in an ultra insulated house, as electricity which has no standing charge could work out with a higher rating than gas.

· The Energy Cost Deflator adds an unnecessary complication and is in place to allow for inflation - if only rating was given in Energy terms this would be avoided entirely. The Energy Cost Deflator has had to be adjusted from 0.96 in 1994 to 1.05 in an attempt to ensure that the SAP remains approximately the same for the same house. This once again is the consequence of a monetary approach. While aggregate fuel prices may be adjusted correctly by the Deflator, the relative standing of one fuel with another may change meaning that changes in SAP Rating will take place purely on the choice of how the Deflator is calculated.

· With the 1994 Regulations it was theoretically possible to achieve a SAP rating over 100 – in fact as high as 115. It would appear that the formula chosen to calculate this was chosen to ensure that at SAP Rating of 100 could be achieved with current technology without too much difficulty. The consequence is that with more stringent regulations in 2000 it has been necessary to widen the scale to 120 to allow possible higher ratings being achieved and yet keep SAP ratings of house defined under 1994 regulations approximately at the same value. This is undesirable as it means that that the range is likely to change again in the future, and a much better method would have been to have had a scale that achieved 100 say only is the house was a zero energy house as far as heating was concerned.

9.12 General Procedure for using 2000 Regulations – Compliance Procedures

There are three different methods whereby the thermal performance of a building can be demonstrated to comply with the Building Regulations

· The Elemental Approach· The Target U-Value Method· The Carbon Index method

9.12.1 The Elemental Approach

· Is heating by gas or oil boiler, heat pump, District Heating with CHP, biogas or biomass fuel? If the answer is NO (i.e. normal electric heating or coal), the Elemental Approach cannot be used.

· Are all the U-values <= to those specified in the Table in section 9.1 for 2000?

· If this condition is not satisfied, then the Elemental Approach cannot be used.

· Is the area of windows, doors and roof lights <=25%. If the answer is NO (i.e. normal electric heating or coal), the Elemental Approach cannot be used.

· If a gas or oil boiler is used, is the SEDBUK efficiency >= 78% for gas (80% for LPG, or 85% for oil). If the answer is NO (i.e. normal electric heating or coal), the Elemental Approach cannot be used.

[the SEDBUK efficiency is discussed in section 9.11.4].

If the answer to all the questions is YES, the building will automatically satisfy the requirements of Approved Document L1.

9.12.2 The Target U-Value Approach

· Calculate the Target U-value from the Specified Target U-Value Equation. [This is somewhat involved, and may be read in full in Section 1.18 of the Approved Document]. The Target U-value is a function of areas of floor, roof, walls, windows etc.

· Modify this Target value by multiplying it by a factor of

actual SEDBUK efficiency-------------------------------------- for gas and oil boilersstandard SEDBUK efficiency

[standard efficiency is 78% for gas, 80% for LPG, 85% for oil].

or dividing by 1.15 for electric or coal heating.

[for heat pumps, biomass, biogas, CHP no modification is done]

· Modify the Target value if area of windows which face south exceeds the north facing windows area.

· Calculate the weighted average U-value of all external surfaces.

· If the weighted average U-value is <= Target value, then the requirements of Approved Document L1 are satisfied.

Note: This method can give considerable flexibility in design, e.g. If area of windows is lower than maximum 25% permitted, the U-values of say walls can be reduced. However, this does not encourage higher standards of thermal insulation.

If a condensing gas boiler is used, the Target U-Value is higher and much easier to achieve. However, at present, this could be a serious problem, as if the insulation levels are relaxed and a condensing boiler fitted, what happens in the future when the boiler is replaced. Currently there is nothing to stop fitting a non-condensing boiler at a later date. It is to be hoped that this will not be permitted, but the only way to achieve this is to ensure that non-condensing boilers are no longer sold on the market.

9.12.3 Carbon Index Method

This is the most complex of the three methods as far as calculation are concerned. Essentially, the SAP procedure is followed [see section 9.13] up to the point as which the costings of fuels are introduced. At that point, the actual annual energy consumption is used to compute the annual carbon dioxide emission. this is then translated into an index [section 9.15], and if the carbon index >= 8, the requirements of Approved Document L1 are satisfied.

There is an apparent maximum carbon index of 10, so to satisfy the Building Regulations by this means it would appear at first site that a building scoring 8 out of 10 is probably quite good. However, as will be shown in section 9.13, the actual scale is out of 17.7, and anything above 10 is truncated to 10. In reality a building scoring 8 is really only scoring 8 out of 17.7 or a real rating of 4.5. It would appear that once again the Building Industry have had an impact as a true scale of 4.5 out of 10 would not appear very good.

9.13 The Standard Assessment Procedure - 2001.

The SAP 2001 requirements were published in December 2001 and are now available on the WEB and linked from the Energy WEB Page links at:

www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/sap2001.pdf

Both the 1994 and 2001 Procedures are largely the same with a few minor points of difference. For the 2005 version see section 9.14.

1) Determine the U-Values for all the components, or use standard tables where relevant

2) Check that U-values are actually achieved (in cases where multiple construction is used it may be necessary to prove that bridging effects do not adversely affect U-value.

2) Work out gross overall heat requirement (Heat Loss Rate)

3) Determine overall hot water requirements

5) Determine incidental gains and also solar gains

6) Work out effective gains (i.e. not all incidental and solar gains are useful)

7) Compute an effective internal temperature - this will be dependant in part on mode of control provided, and noticeable improvements in SAP rating are possible just by changing control = e.g. zone control, thermostatic radiator valves (TRV's) etc.

8) Evaluate corrected degree-day parameter

9) Estimate net space heating total energy requirement.

10) Select Heating Method

11) Include energy requirements for pumps etc.

12) make allowance for appliance efficiency and determine corrected Total Energy Requirement from (5), (9) and (11).

The above procedures are also required in calculating the Carbon Index (section 9.14) and the new DER (section 9.15)

13) estimate energy costs of total space heating, hot water and pump at 1994 prices (or 2001 prices)

14) Deflate energy by Energy Cost Factor (which is related to floor area) and use standard formula to compute SAP. Deflator was 0.96 for SAP 1994 and is 1.05 for SAP 2001.

Note: There are fixed fuel prices declared in both 1994 and 2001 SAP rating methods

http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/sap2001.pdf

9.14 SAP Rating for 2005 Regulations.

While the basic methods are generally similar in the 2005 Regulations to those previously, there computations are more complex and take into account other factors such as the proportion of the windows, covered by frames, the extent of solar heating etc.

However, the most significant effect is the compete recalibration of the scale. Whereas the SAP Rating in 2001 meant that approximately the same rating would be given to a house calculated on the 1994 regulations, a house which already has a SAP rating will find it reduced under the new procedures. This is a further reason why the final stages of the SAP Rating analysis are meaningless and should be abolished. The initial stages are fine as they are used for the Carbon Index (2000 Regulations), and the new DER calculations. It is the attempt to relate the SAP Rating to monetary values which is the problem in the SAP Rating, particularly in a time of fast changing energy prices.

The SAP 2005 rating is related to the energy cost factor by the equations:

if ECF ≥ 3.5, SAP 2005 = 111 – 110 × log10(ECF) (1)if ECF < 3.5, SAP 2005 = 100 – 13.96 × ECF (2)

where ECF = Energy cost factor, calculated in box (99) or (99*) of the Worksheet.

SAP ratings can also be obtained by using Table 14 of the SAP2005 tables see. http://www2.env.uea.ac.uk/gmmc/energy/env2d02/pdf/Final_SAP2005_tables.pdf

The SAP rating 2005, unlike previous versions now takes into account energy for lighting and the effect of thermal bridges, and also takes account of energy generated in the dwelling using technologies like micro-CHP or photovoltaics.

The SAP rating scale (1-100) has been set so that SAP 100 is achieved at zero-ECF. It can rise above 100 if the dwelling is a net exporter of energy. The SAP rating is essentially independent of floor area. The SAP rating is rounded to the nearest integer. If the result of the calculation is less than 1 the rating should be quoted as 1.

The idea of having a SAP rating of 100 for something which has a zero cost is an improvement on previous versions. However, the fundamental problem of trying to relate performance to energy prices is still a serious limitation in the period of widely fluctuating energy prices.

9.15 The Carbon Index Calculations (2000 Regulations).

The calculation of the Carbon Index is a major step forward and for the first time attempts to assess the true environmental performance of a building.

The stages in computation follow steps (1) – (12) of the Standard Assessment procedure as outlined in section 9.12.

The procedure then continues as follows:-

13) From the computed fuel use, determine the total amount of CO2 emitted by the building.

14) Determine the Carbon Factor (CF) by dividing the total CO2 emission as follows

CF = CO2 /(TFA+45) where TFA is total floor area, i.e. it is the carbon emission per modified floor area.

The determine the Carbon Index (CI) from

CI = 17.7 – 9.0 log10(CF) The Carbon Index ranges from 10 with a low CO2 emission to 0 for a high emission.

The last equation is where the complication of a scale going beyond 10 arises (see section 9.12.3). If the Carbon Factor (CF) computes to less than 7.17, then it is to be treated as zero.

The use of a scale going from 0 (high carbon emission) to 10 (low carbon emission) also confuses some people (who think a low number is better).

Fig. 9.1 shows what the carbon emissions would be for the same house designed to different standards. It can be seen that the emissions have fallen from 70 kg CO2 per m2 per year to less than 10.

Fig. 9.1. Variation in carbon emissions with different Building Standards



Fig. 9.2 Enlargement of part of Fig. 9.1 to show performance of Elizabeth Fry and ZICER Buildings in relationship to Theoretical 10 out of 10 building.

The present regulations indicate that compliance is achieved with an emission of about 11 kg CO2 per m2, corresponding to a carbon index of 8. However, if a true scale were used then both the Elizabeth Fry Building and the ZICER Building would outperform even the theoretical 10 out of 10 building – see Fig. 9.2.

9.16 The Dwelling Emission Rate (DER)

The Dwelling CO2 Emission Rate (DER) is equal to the CO2 emissions per unit floor area for space and water heating and lighting, less the emissions saved by energy generation technologies, expressed in kg/m²/year to two decimal places.

The calculation should proceed by following the appropriate section of the SAP worksheet, designed for calculating carbon dioxide emissions for:

a) individual heating systems and community heating without combined heat and power (CHP); or

b) community heating with CHP and waste heat from power stations.

The Environmental Impact Rating (EI rating) is related to the annual CO2 emissions by:

CF = (CO2 emissions)/(TFA + 45) (3)if CF >= 28.3 EI rating = 200 – 95 × log10(CF) (4)if CF < 28.3 EI rating = 100 – 1.34 × CF (5)

where the CO2 emissions are calculated in box (112) or box (119*) and TFA is the total floor area of the dwelling as in box (5). The figures in brackets relate to boxes in the worksheet which may be seen at :


The EI rating scale (1-100) has been set so that EI 100 is achieved at zero net emissions. It can rise above 100 if the dwelling is a net exporter of energy. The EI rating is essentially independent of floor area. The EI rating is rounded to the nearest integer. If the result of the calculation is less than 1 the rating shouldbe quoted as 1.

As with the SAP Rating, the arbitrary selection of this non-linear scale is questionable although at least in this case it is not influenced by relative pricing of fuels. Furthermore, unlike the Carbon Index of SAP 2001, there is no truncation of the scale.



9.17 Supplementary Notes on U-values/heat Loss calculations

9.17.1 A simple way to assess a revised U-value.

If the U-value of a component is changed by adding insulation, it is easy to calculate the revised U-value as show in the following example:-

Let the U-value of the roof be 0.5 W m-2 oC-1 - i.e. with about 50 mm of insulation already.

- What will be the new U-value if an additional 100 mm of fibre glass of conductivity 0.04 W m-1 oC-1is added

Remember U-value = 1/ R, and working with unit areas,

so initial value of R is 1/0.5 = 2.0 m2oC W-1

resistance of additional insulation is 0.1/0.04 = 2.5 m2OC W-1

Hence new resistance is 4.5 m2OC W-1

and new U-value is reciprocal of this i.e. 0.22 W m-2 oC-1

9.17.2 Calculation of U-values for a floor

Calculating U-values for a solid floor is not as easy as with other components as the path length from the heated area to the outside varies depending on whether it starts near an outside or near the centre of the floor slab. It is also complicated by the nature of the underlying material. The U-value is largely a function of the size and shape of the floor slap and a good approximation may be

obtained by determining the external perimeter (P) of the slab and its area (A). A good approximation for floors without insulation may be gained from the following equation

For floors with insulation - i.e. all cases post 1985, the easiest way to work out U- value is to compute the raw U-value without insulation as above and the revise the U-Value using the procedure outlined in section 8.15.1 above.

9.17.3 Energy Conservation - Savings Arising From Partial Heating of a Dwelling.

One practical group asked this question during the session in week 3 in the 2004 class.. The following illustrates how to calculate this saving. The example shows a shows bungalow with 25% of the area unheated and constructed to 1976 Regulations and not improved subsequently.

The key point to note is that the heat transferred across the internal walls to the unheated area will equal the heat loss from the unheated area.

WARNING: ONLY FOR THOSE WHO ARE INTERESTED AND CAN UNDERSTAND THE MANIPULATIONS. HOWEVER, all of you should attempt to understand the logic behind the method as shown in italics below.

The key issue in this cases is continuity. That is the heat loss from the heated region equals the heat lost from the unheated region to the outside.

Though we may know the heated temperature, and also the outside temperature, we will not know the temperature of the unheated space, and this we must find from continuity.

Once we have done this we can work out the heat lost from the unheated region to the outside and compare this to the situation if heat had been supplied to the region.

. Single storey building having following U-values:-

Ufloor = 0.6 WoC-1

Uroof = 0.5 WoC-1

Uwall = 1.8 WoC-1 * (weighted average over walls and windows)

UINT = 2.8 WoC-1 - Internal walls

* Effective U value using 1976 Building Regulations (equivalent to 17% glazing)

Wall height = 2.5 m

Let temperature of heated region = T1 temperature of unheated region = T2 external temperature = To

Assume 2 air changes per hour in heated area, and one air change in unheated area

floor area of unheated part = 16 m2

... floor area of heated part = 48 m2

Heat loss through external walls for heated region = (8 + 8 + 4 + 4) x 2.5 x 1.8 = 108 WoC-1

floor = 48 x 0.6 = 28.8 WoC-1

roof = 48 x 0.5 = 24 WoC-1

vent. loss = 48 x 2.5 x 2 x 0.361 = 86.6 WoC-1 Total loss = 247.4 WoC-1

Hence total heat loss through external walls = 247.4 (T1 - To) W

Heat loss through internal walls = (4 + 4) x 2.5 x 2.8 x (T1-T2) = 56 (T1-T2) ---------This value also equals gain by unheated area

Heat loss from unheated area to outside:-

external walls (4 + 4) x 2.5 x 1.8 x (T2-To) = 36 (T2-To) roof 16 x 0.5 x (T2-To) = 8 (T2-To) floor 16 x 0.6 x (T2-To) = 9.6 (T2-To) vent. loss (1 ach) 16 x 2.5 x 0.361 = 14.4 (T2-To) Total loss = 68 (T2-To)

When equilibrium conditions have been reached

Heat gained in unheated region = heat loss from unheated region

... 56 (T1-T2) = 68 (T2-To) i.e. T1-T2 = 1.215 (T2-To)

hence 2.215T2 = T1 + 2.215To - To

If temperature difference between heated area and outside = T, = T1 - To

temperature difference between unheated area and outside =

T2 - To = To + 0.451 (T1-To) - To = 0.451 (T1 - To) = T

Heat loss between unheated area and outside = 68 WoC-1 (from above)

Hence total heat loss = 68 x 0.451 x T = 30.7 x T

If unheated area had been heated and occupied as the remainder of the house, the temperature would now be the same as the rest and the ventilation rate would be 2 air changes per hour

heat loss would then be = 68 + 14.4 = 82.4 WoC-1 | extra ventilation

Hence heat loss = 82.4 T Watts

saving by keeping room unheated = 82.4 - 30.7 = 51.7 T Watts

Total heat loss if whole building is heated = 247.4 + 82.4 = 329.8 W

Thus saving = 15.7% (i.e. 51.7 / 329.8 x 100%)

If there are 2430 degree days, annual consumption at 100% efficiency

= 329.8 x 86400 x 2430 = 69.2 GJ per annum | seconds in a day

saving by keeping one room unheated = 10.9 GJ per annum

If on the other hand the unheated room had been heated but the air-change rate had remained at 1 air change per hour, the savings would be somewhat less being 37.3 T Watts

representing a saving of 11.8%

The annual consumption with whole house heated would then be 66.2 GJ and the saving 7.8 GJ.

Space for Additional Notes about Building Regulations

N.K. Tovey ENV-2D02 Energy Conservation – 2006 Section 10 Electricity Conservation

10. ELECTRICITY CONSERVATION

10.1 Introduction

Conservation of Energy with respect to Electricity is much more complex than for other forms of energy. There are five separate aspects which must be considered:-

1) growth in use of appliances and refrigeration 2) the issue of “STANDBY”3) technical improvements leading to more efficient use of

electricity4) controlling demand for electricity5) fuel switching to electricity

The second of these will reduce the demand for electricity while both the first and the last will have the reverse effect and will probably outweigh any savings from improved technology. Technical improvements are important in reducing electricity demand, but as important is the need to control the demand.

These four aspects will be considered separately:-

10.3. Potential Growth in Electricity (excluding fuel switching).

Unlike all other developed countries, the demand for electricity remained approximately constant for about 10 years from 1973 and has since seen a growth of 1.8% per annum since 1982. The reason for the static demand arose from conflicting trends where a reduction in demand in some areas counterbalanced a growth in other areas. In the domestic market for instance, a significant reduction in electric space heating requirement offset a growth in both refrigeration and the use of appliances.

The reduction in electric space heating followed the spread of fossil fuelled fired central heating and from now on is likely not to reduce further - in fact recent trends show a rise. While most household have a refrigerator, there is still potential growth in the ownership of freezers. equally, the consumption from the use of appliances is showing a continual increase with no signs of saturation. Finally, though a substantial reduction in the amount of energy used for televisions was noted in the mid 1970s with the advent of solid state circuitry, the move towards HDTV, digital TVs and TVs with standby control is reversing this reduction. Finally, there is a continued reduction in the household size so that even with a static population, the electricity used in the domestic market will rise.

There are two significant areas where a substantial rise in consumption might occur - these arise indirectly from fuel switching and are covered in section 10.7.

10.3 The Standby Problem Increasing numbers of appliances now have a level of electricity consumption even when they are off. It is estimated that of a typical household bill as much as 15% or more is associated with this use. Some of the use is via the so-called “Standby” issue where remote controls are used to activate an appliance. Common ones include DVDs, TVs, Video recorders, Cable/Sky boxes, CD players etc. Typically each one of these will consume around 10 – 15 W when in the standby mode. If an appliance is used 2 hours a day on average (with a consumption of say 100W – a non digital television), then the consumption during standby will be as great as and in some cases more than the total energy used during viewing.

In addition to the appliances listed above, others such as mobile phone chargers etc have a power pack which gets warm and if left on when the mobile phone is taken away will consume electricity unnecessarily. A straw poll taken last summer suggested that as many as 60% of people may leave the such chargers plugged in.

There are other examples of quasi – standby use – e.g. portable phones, FAXes, and any appliance where there is a light on. Look in a kitchen and see how many green or red lights are on. Some certainly can be switched off when not in use.

The problem with most appliances with standby is that they usually work from low voltage DC electricity and there must be a transformer and rectifier to transform from the normal AC electricity. If you feel the power pack on a lap top computer you will see how hot it gets, and this is replicated in all entertainment appliances.

Even switching an appliance off on the actual casing itself does not guarantee that no power is consumed. Unless you are confident that it does not then the only sure way is to switch off at the wall.

The reason why, even when no light appears on an appliance depends on where the transformer is positioned. In cheaper models the ON/OFF switch on the appliance itself is located AFTER the transformer. This means it is cheaper to make products for the global market as only the transformer has to be changed. This is illustrated in Fig. 10.1

Contrary to popular belief, most appliances e.g. TV’s etc SKY/Cable boxes, Freeview etc DO NOT loose their settings if turned off. I have been testing them myself repeatedly over last few months and have encountered no problem or loss of program setting etc. Switching off a SKY/Cable box when not actually watching will save up to 130 kWh a year (£13) and save the emission of 60+kg of carbon dioxide from one box alone.

a) Switching off the appliance will disconnect power in this configuration.

b) this type of appliance has the switch on the downstream side of the appliance and will not turn off current used in transformer by switching off. Appliances like this can only be properly switched off by switch off at the mains switch on the wall.

Fig. 10.1 Two types of switch arrangements.

Settings circuit

transformer

Main functional circuits

Switch control by STANDBY

Plug for appliance

transformer



Plug for appliance


c) Arrangement for an appliance with a critical circuit – e.g. settings on video recorder for time recording. The standby can be switched off but the setting control circuits still consume energy

d) A solution to the problem. The critical setting control circuits are powered by an independent source such as a rechargeable battery. The settings are retained, and the battery recvharged next time the device is used in full.

Fig. 10.1 continued – Arrangements for using standby where a circuit has a critical function. (c) normal approach which is energy wasteful; (d) an intelligent solution to cut unnecessary waste. There are other solutions too.

In some cases like a video recorder there may be an issue as the settings are personal to the machine not fed from a central source, but smart intelligent standby appliances are now coming on the market – in fact there has been much in the press on this issue recently. The Gleneagles Summit referred to it and the International Energy Agency (IEA)is promoting this under the so-called “1 Watt” initiative and this may become law in the EU shortly.

A full account of this initiative may be see in the publication:

“Things which go BLIP in the night”

www.iea.org/textbase/nppdf/free/2000/blipinthenight01.pdf

while there are summaries at:

www.iea.org/journalists/docs/standby.pdf - this is a one page summary, and

www.iea.org/textbase/papers/2002/globe02.pdf which is a six page summary.

10.4 Technical improvements to reduce electricity consumption

All electrical appliances are nearly 100% efficient in converting energy into forms which are of some use. It should be noted that the alternative clause ... converting delivered energy into Useful Energy ..... was not used here. The latter definition implies energy in the form that it is required. Thus a tungsten filament light bulb

is 100% efficient in converting electricity into energy which is useful (i.e. as light or as an incidental heat gain). However, there are many areas where the USEFUL ENERGY output can be improved. Fluorescent lights consume much less energy than the equivalent tungsten filament bulbs (~20%). The low energy light bulbs of this type. However, further improvements are possible by changing the frequency of operation from the standard main frequency ( changes are now relatively inexpensive). A second improvement is through the use of electronic control which incorporates a form of power factor correction.

In standard fluorescent tubes, the older T12 consume around 20% more than the newer T8 units. The latest T5 are even more efficient.

Microwave/radio frequency heating uses much less energy than resistive heating as does infra red heating in some situations.

Other improvements include improved insulation on ovens/refrigerators and by the use of mixed fuel appliances such as washing machines and tumbler dryers. These latter use gas for the heating (which is more energy efficient) and electricity for the motor drive. There are relatively few such devices on the market, but the White Knight BG437 Standard Gas Dry Tumble Dryer is one example.

10.4.1 Power Factor Correction

All electrical machinery (and fluorescent lights) waste energy through what is known as the reactive load component. For tungsten filament lights and electric fires the reactive component is small and is of little consequence, but in the case of a motor as much as 20-30% of useful energy is effectively lost.

In alternating current (as supplied to our homes), the voltage at the LINE terminal is oscillating in a sine wave from a maximum of +340 volts (in the UK) to a minimum of -340 volts at a frequency of 50 Hz. The root mean square voltage (i.e. the effective voltage) is 240 volts. At the same time the current is also oscillating at the same frequency. For a truly restive load, the current and the volts are in exact phase and the power (in watts) is given simply by:-

Fig. 10.2 Alternating Current showing voltage out of phase with current in a typical appliance

power = volts x amps

For a power of 1 kW the current flowing in a house in the UK will be 1000/240 = 4.17 amps. However, in most AC situations the current will be out of phase with the volts and the above equation becomes:-

transformer



Plug for appliance

Setting control

transformer



Plug for appliance

Setting control

Rechargeable battery

http://www.iea.org/textbase/papers/2002/globe02.pdf

http://www.iea.org/journalists/docs/standby.pdf

http://www.iea.org/textbase/nppdf/free/2000/blipinthenight01.pdf


power = volts x amps cos

where is the phase angle, and the term cos is known as the power factor. Some appliances cause the current to lead the voltage - for others the reverse is true.

For an inductive load, the current leas the voltage and by placing a capacitor (which cause the current to lag) of appropriate size, the angle can be reduced to zero and the power factor increased to unity. This is known as power factor correction. Typically cos is between 0.7 and 0.8 and thus there is a 20-30% loss from the power actually supplied to the effective power out.

Power factor correctors must be correctly sized for the type of appliance in use and have been available in industry for many years and are now available for refrigerators and freezers in the domestic market. They will save about 20%+ but are quite expensive (£25 - 1994 figure) and will take 2-4 years to pay back investment. in the UK. However, since then most efficient refrigerators already incorporate Power Factor Correction and thus there is little relevance now in appliances of this type.

10.4.2 Kilowatts, kVA, kilovars

For most applications we talk of kilowatts (i.e. it is the product of volts multiplied by the in phase current). Whenever we have a reactive load (such as a motor) then there is a second component which is the REACTIVE POWER (kiloVARS) which is the product of the reactive components of the volts and amps (hence VAR - volt- amp reactive). This reactive power is at a phase angle 90 degrees to the normal power. The result power (or VA - volt-amps i.e. the product of the volts and amps irrespective of phase). This is illustrated on the diagram below:-

Fig. 10.3 relationship between kilowatts, kiloVars and reactive power.

In many situations (particularly in industry, the university etc), payment for electricity is made in terms of kVA. Since it is only kW which is of use, such establishments will unless there is power factor correction, waste energy unnecessarily.

10.5 Controlling the demand for electricity

10.5.1 Introduction

Since the war it has been the general policy of the Electricity Supply Industry (both pre and post privatisation) to meet the demand for electricity rather than to control it. Unlike most other sources of energy (either in primary or secondary form) electricity cannot be stored. Even the pumped storage schemes at Dinorwig, Ffestiniog, Loch Awe, and Cruachan combined can only provide about 10% of electricity and then only for 5 hours. Since in a regime of meeting demand generating capacity must be available at

all times in case there is a demand, this will inevitably lead to some waste. There has been a limited amount of load management for several years, but the scope is much greater, and the need for control will become more significant with an increased renewable component within the generating capacity.

The problem in the distribution of electricity is the large change in demand from day to night and even from hour to hour or even minute to minute.

10.5.2 Meeting the demand for electricity

Fig. 10.4 shows a typical demand curve for a winter’s day and typical summer’s day. The curves are similar but displaced by about 10 GW which is approximately constant from day to night showing that the electric heating requirement in the off peak period is about the same as that for standard rate electricity. Several points about the curve should be noted:

1) the steep rise in demand between 0600-0900, a sharp peak between 16.30 and 18.00 in the winter and about 2100-2200 in the summer.

2) the late afternoon winter peak is more pronounced than a few years ago.

3) there is hardly any reduction in demand around mid-day - a feature which was common about 20 years ago.

4) the later afternoon winter peak coincides with the end of the working day, and the beginning of a requirement for lighting.

5) the summer late evening peak coincides approximately with the summer lighting up time.

Fig. 10.4 Electricity Demand Curves for August 6 th 2003 and January 28th 2004.

6) there is a small peak about 0100 which coincides with the switching on of storage radiators.

Load Management is sometimes used to reduce the demand at peak times – see section 10.5.6


Fig. 10.5 Meeting the Demand [ this diagram will be completed in the lecture]

Fig. 10.5 shows how this demand is met on a winter’s typical day. Nuclear Power was approximately constant throughout the day while coal fired generation rose from an overnight low of 21 GW to a daytime maximum of 32 GW. The transition from night to day was smooth so that once a station was on line it was generating for a minimum of 9 hours. Oil fired power stations were used very little (even the big ones like Grain, etc.) and their utilisation varied somewhat from hour to hour. The remaining part of the demand was met by hydro and the two pumped storage schemes at Ffestiniog and Dinorwig. The combined capacity of these two pumped store schemes is 2160 MW.

There are similar schemes in Scotland at Loch Awe and Cruachan. Pumped storage schemes operate by pumping water from a low level reservoir to a high level reservoir by using electricity generated in coal and nuclear power stations in periods of low system demand - e.g. overnight. During the day time, and particularly at peak periods the water is released, and electricity is generated in the way it would be in a normal hydro-electric station. Fig. 10.6 shows the utilisation of the pumped storage stations both in generation, and pumping.

Fig. 10.6. Pumping and Generating at Dinorwig – actual data from 25th May 2005. The X-axis represents the standard time periods which are half-hour long starting at midnight

Thus the function of the pumped storage schemes has been to smooth out the load on the fossil fuel power stations. It must be noted however that there is a net loss in available energy as about 10% is lost in the pumping and a further 10% in the generation so only 80% of the electricity used in pumping can be extracted. However, this loss must be offset against running fossil fuel stations more continuously, and hence efficiently, and minimising the requirement for short operation of fossil fuel plant at peak times. The need for such pumped storage schemes arises from the fact that the UK unlike most other countries has a very small capability in hydro-electric generation.

Equally, all European countries except the UK, Ireland and Iceland are interconnected so that temporary surges in demand in one country are covered by a much larger system and the effects of sudden changes in demand are less noticeable. There is currently one inter-connector to France is 2000 MW and this by itself cannot cope with the largest surges experienced on the UK system where a sudden surge of over 2500 MW is not uncommon. On one occasion in 1990, there was a surge of 2800 MW in a 150 second period. This is equivalent to 2.5 times the output of Sizewell B. The surge lasted just a few minutes.


Currently a second inter-connector is under construction to Norway – this will be rated at 1320MW.

Fossil fired power stations take from 6 - 24 hours to warm up during which time they are consuming energy but supplying no electricity. After warming up they must be synchronised to the grid under load and then "loaded" to maximum output. The maximum rate of loading of any one unit is about 8MW per minute which means that it will take up to an hour for a generating set to become fully loaded.

Equally, although there is some scope for "load following", the relatively slow response of most units means that sudden changes in demand cannot be accommodated in this way. . Thus the hydro capability of the pumped storage schemes becomes particularly attractive for use at such periods as the Ffestiniog station can come on line in 30 seconds, and the Dinorwig scheme in 10 seconds.

Even so, these stations cannot cope with all the sudden demands imposed on the system such as shown in Fig. 10.4 on the day in question (i.e. the example shown previously relating to the World Cup Semi-Final between England and Germany in 1990) a surge in demand of nearly 10% took place in about 3 minutes as a direct result of television programmes.

There are a series of open circuit GAS TURBINE stations of approximately 100 MW capacity to help in such demands. These should not be confused with the CCGTs (combined cycle gas turbines) which have become newsworthy in the "dash for Gas" These stations, although running at a significantly lower efficiency than the steam generating stations have the distinct advantage that they can become fully operational in 2-3 minutes and are thus particularly suited to short term operation. Such gas turbines are used in conjunction with the pumped storage schemes to smooth out the effects of sudden demand or the sudden failure of generating equipment or climatic change (thunderstorms, wind, ice, snow) on the transmission line.

As an additional safeguard in meeting the demand, and number of stations are often run under a lower load than normal so that there is scope to increase the combined output from several lightly loaded station simultaneously. Thus if three stations each with 4 500 MW sets operating at 80% load i.e. 400 MW, then at a time of sudden demand, these stations could increase there collective output of 3 x 4 x 400 = 4800MW at a rate of 4 x 3 x 8 = 96 MW per minute up to a maximum of 6000 MW (i.e. over a period of 12.5 minutes. If these peaks (either short term or longer daily peaks) can be reduced then significant savings may arise and more importantly, the need for new generating capacity can be reduced or delayed.

Since the introduction of the New Electricity Trading Arrangements on March 27th 2001, there has been a financial incentive to run units under low load so as to respond rapidly to sudden changes in demand, however, the maximum rate of change is limited to around 8MW per minute per unit, and thus the opportunity to respond to very significant changes is limited.

10.5.3 Shifting Demand

There are two types of peak that must be addressed here.

1) the day time peak2) the short term transient peak (arising primarily from

TV scheduling).

The Electricity Supply Industry has attempted to shift part of the peak load to fill the night time trough. This has been achieved in the domestic market by the introduction of storage heaters.

However, these are only truly an improvement if they represent a switch away from direct acting electric heating. Unfortunately, the marketing of such appliances is as a means of central heating in direct competition with fossil fuels. At the same time, the Electricity Supply Industry run power stations overnight to pumped water uphill in the pumped storage schemes. This means that more coal fired power stations can be run base load at night (i.e. this will improve their efficiency), while the pumped storage stations can be operated to meet sudden peak demands. While this inevitably means that we can meet the sudden changes in demand, it is a debatable question as to whether fossil fuel energy is actually saved as although more stations are running at their design efficiency, the pumped storage schemes are only 80% efficient themselves (i.e. they only provide 80% of the energy used to pump the water uphill).

10.5.4 Financial Incentives to shift demand

Financial incentives are available using the Economy 7 and the recent Economy 10 to encourage domestic consumers to use more at night time (or a specific times of the day), and less at other times. The normal domestic tariff for electricity, the charge (Jan 2004 prices) is around 6 – 6.5p. In Economy 7 the night time tariffs are substantially reduced during which time the storage heaters are timed to "charge" (i.e. 2.74p per unit), but this is compensated by a higher standing charge (£14.30 as opposed to £9.10 per quarter).

The day time rate is the same as for the standard tariff. To break even there needs to be at least 1.25 kWh of electricity consumed in the 7 hour charging period. The storage heaters do not operate during the day time, and the actual break-even point depends on the amount of electricity used over night.

For the average household (without storage heaters this will be around 0.5-0.8 kWh (refrigerator/freezer use), while a minimum of 1.25 kWh each and every night (including the summer) is needed to make Economy 7 attractive.

Unless one has either storage heaters or hot water (electrically heated), or preferably both, it will not pay to be on the Economy 7 tariff. If one has Economy 7, then it will also pay to use the washing machine and tumbler drier overnight.

Economy 10 (or !0 hour tariff) is available in some regions only and is different in that it not only allows the consumer to charge the storage heaters overnight (and also use other night time appliances overnight 5 hours instead of 7 hours with Economy 7), but it allows for special radio control of the storage heaters to come on for two separate periods of up to 2.5 hours (not necessarily continuous) during the afternoon and evening.

For all electricity use in the 5 hour overnight period, and for storage heating/electric hot water heating in the special 2.5 hour periods, the price per unit is lower than the standard rate (at 3.30p per unit) but substantially above the Economy 7 Tariff. The nice thing about this arrangement is that the Electricity Board can time the day time charge period to coincide with slightly lower periods of day time demand, and can therefore act to counteract the sudden peaks in demand.

On the other hand, to aggressive marketing here could lead to an overall increase in total electricity demand. It should be noted that the overnight period starts at 02:30 to avoid the small peak at about 0100 - 0130 as the Economy 7 heaters switch on.

Note : A householder may opt for Economy 7 or Economy 10 at any time, but then must continue to be charged under this rate for a minimum of 12 months.


While the promotion of the Economy 7 and Economy 10 tariffs will help to reduce the peak demand in electrically heated homes, there will also be an incentive for people installing central heating to opt for electric method as the capital outlay will generally be less than other systems, particularly if only part central heating is required. Thus this will then encourage people to use electric resistive heating. Since there is an energy overhead of about 2.8 (i.e. the primary energy ratio) for every unit consumed any move in this direction will tend to increase total energy consumption.

The net effect of off-peak electricity and the use of pumped storage facilities has been to significantly fill the troughs and demands and this can be judged by the improvement from 45-50% to 55-60% in the overall system demand factor. Currently the total demand for electricity is rising at about 1-2% per annum while the peak load is rising by only 0.5-1.0%.

Note: There is a discount available for all domestic consumers who pay by standing order. However, the monthly payment is constant throughout the year and thus there is no incentive for the consumer to adjust energy use as the payment is divorced from actual use.

10.5.5 Financial incentives to deter use of electricity at peak periods

There are several different financial disincentives to use electricity at peak times. In one respect, the Economy 7 tariff could be argued to fall into this category. However, such a tariff is chosen freely by the consumer whereas in this section we shall be considering tariffs which vary according to external events (usually climatic or seasonal).

There are several different approaches here:-

1) Maximum Demand Tariffs2) Seasonal Tariffs3) Time of Day Tariffs4) Tariffs which vary according to other factors.

The exact construction of a particular tariff will vary from one Electricity Company to another. The examples show below are taken from one UK Company (Eastern Electricity) and three from the USA - Arizona Public Service, the Salt River Project (Arizona) and one utility in South Carolina.

Maximum Demand Tariffs

Maximum Demand Tariffs are available to large consumers like UEA. There are two basic types – one which relates to a standard charging regime throughout the day, while the second has two different tariffs similar to Economy 7.

There are also differences in the tariffs as to whether the metering is done at high or low voltage. If it is done at high voltage, then the customer takes responsibility of any conversion losses to the lower operating voltage and thus the unit charges will be less.

Whereas a few years ago it was relatively easy to get tariff data for Maximum Demand Tariffs, it is becoming difficult as each consumer usually negotiates for an individual tariff.

However, the following gives an example of the tariff which was in operation at UEA a few years ago.

The Maximum Demand Tariff 6 (which was relevant for UEA) was made up of several parts. There is:-

1) A standing charge for each month £92.92 charge for use of the system

2) An availability charge for each kVA of power required

£ 1.03 per kVA of potential demand

There is also a charge for units consumed in the 30 minute period of maximum demand during the month. This varies according to month

March - October NIL November and February £2.17 December and January £6.92

A unit charge (midnight to 7 am) 2.45pUnits at other times of day 5.32p

A REACTIVE POWER charge for each kiloVAR 0.18pin excess of half the number of units supplied

Note:

1) The REACTIVE POWER charge only becomes relevant if the overall power factor falls below 0.895.

2) The system charge is a fixed charge for maintenance of the system.

3) It should be noted that the Area Boards actually make a loss for each unit sent out at certain times of the day.

3) The charge for each unit during the period of maximum demand is at a punitive rate (i.e. 130 times the normal day time rate in January). This means that a single half hour period in January can account for 30% of the total electricity bill for the whole month.

There is thus an incentive to keep the peak demand to a value only marginally different from the average demand. However, since this applied retrospectively, and since in general the actual time of the peak demand is unknown in advance it may be difficult for such a tariff to have much effect. For efficient use, it does require a careful record keeping of the hourly consumption to see at what time of day the maximum occurs and then take steps to minimise the demand each day at that time.

5) None of these measures actually reduce consumption as

the effect is only seen retrospectively. However, it is hoped that it might have some effect in the future.

Seasonal Tariffs

Some utility companies apply a different charge per unit depending on the season of the year. Thus the Arizona Public Service charges a higher price in summer when air-conditioning load is at its highest. However, for small users (< 400 units per month) the tariff remains the same as in the winter. Arizona Public Service have been operating such a system for over 20 years.

Time of Day Tariff

An extension of the Economy 7 idea is to have several different charging periods during each day. The Salt River Project in Arizona has had such a system for the last 18 years for all consumers with the meter recording consumption in five separate periods each day. Since the cost of generating electricity becomes greatest when the load is at a peak, the tariffs charged reflect the time of day the power is used. The tariffs vary over a factor of 3 during the day. A wise consumer will thus ensure that head loads - e.g. washing machines etc are used at periods other than peak tariff periods. No such facility is available to the domestic market in the UK although there have been a few trials. The price of electricity within any defined period remains constant for a given period (usually a year).


A true time of day tariff would reflect the actual cost of producing electricity at that time. With computer technology there is no reason why such information could not be displayed prominently in each home allowing the consumer to decide how to use power. The actual price changes would be triggered by encoding a signal within the national radio service (e.g. Radio 4). Demonstrations of this were shown on Tomorrow's World in the mid 1980's and there have been a few trials of such a system, but no Area Board in the UK is using such a system.

Tariffs according to other factors

At least one utility in South Carolina uses mean temperature as the key to tariffs. Thus when the mean external temperature exceeds 26 oC, it is found that the air-conditioning load increases rapidly. The charges for each unit of electricity are higher on such days.

10.5.6 Load Management Schemes

There have been a number of Load Management Schemes in operation, and it is clear that there will be many more in the future. These can be broadly divided into those affecting large consumers such as industry and those affecting the domestic customer. In the UK these apply only to large consumers, but in North America innovative schemes have been introduced for the domestic consumer.

Large Consumers - usually much larger than UEA

The basis of a Load Management scheme is the ability for the Electricity Supply industry to directly control demand either by previous notification or by direct action using radio telemetry. In the current regime of a privatised industry, the details for the Load Management Schemes are less easy to obtain. However, the basically work by the authority - the Area Board usually - requesting that a consumer shed a given amount of load (usually at least 1 MW) at a given time.

Typically the load management time is for no more than 2 hours on any one day with a maximum of say 100 hours in a year. Warning is given, but the actual charge for units will depend on the length of warning that the customer is prepared to tolerate. Thus the best tariffs are charged for those consumers who are prepared to have only 15 minutes warning of a load management shedding. Other schemes operate with up to 24 hours notice. The tariffs offered are attractive provided that consumers conform. In some cases the consumers do have an option of overriding the request for cutting the load, but only at punitive rates.

The scheme is particularly attractive to the Electricity Supply Industry as it tackles the problem of the peak demand, and at time up to 1GW or more of load have been shed in this way. This, more than any other action has improved the system load factor and reduced the need for new power stations.

Small/Domestic Consumers

In the UK there have been a few experimental research schemes in which a limited number of domestic consumers have been involved in Load Management Schemes. In these the electricity Area Boards have installed devices which can switch off appliances in the various homes by remote control, i.e. by the Area Boards and not by the individual householders themselves. By participating in these schemes the householders can enjoy cheaper electricity to compensate for the inconvenience.

While such schemes are experimental in the UK, there are currently full schemes in operation in parts of the USA. For

instance Florida Power allows the consumer to opt for one or more of the following items to be switchable by the utility company.

1. Central heating2. Air-conditioning3. Swimming pool filtration plants

By selecting one of these a consumer will be eligible for a refund of about $4 per month (1984-85) from his electricity bill and up to $12 (maximum) if he opts for all three schemes. The scheme operates by a radio controlled device installed at the consumer’s premises and linked to the appropriate circuits. Each day is divided into peak time and off-peak time zones, and it is only during the peak time zones that the load management schemes are operated. Even then, the maximum ‘off’ time is limited to 15 minutes (in the case of central heating) in any 4 hour period for any one consumer. Alternatively the consumer can opt for a longer disconnection (i.e. 30 minutes), and receive a higher discount.

By selectively switching off different groups of consumer throughout the hours of peak-demand, the overall maximum demand can be reduced. The consumer has the choice whether or not to opt for such a scheme, but if he does he must continue with it for a minimum of one year. Interruptions of supply for such short periods are not normally noticed by the consumer, but nevertheless are important in reducing peak demand

A scheme such as this is clearly only one of many which could be implemented. In the scheme described the switching information is fed via radio only from the electricity utility to the consumer and not vice versa. Other schemes could utilise two-way telemetry using either telephone wires or even a high frequency component on the electricity supply wires themselves. With such schemes there would be the added advantage that meter reading could be done remotely by the utility companies without entering the consumer’s premises.

In New Zealand, electrically heated hot water is controlled in a similar manner. Indeed in the power emergency in 1992, hot water was available for only the period midnight to 7 am.

Other possible ideas for Load Management.

Other possible future operations for load management schemes for load management schemes for small consumers are as follows:

i) using microprocessor switching devices controlled by the Area Boards to selectively shed load at peak times in a consumer’s premises, e.g. cut the power circuits, but leave the lighting circuits on. In this way the consumer would not be left in the dark. .

ii) using similar devices as i) to restrict load to a given amount at peak times say 1000W. In this, the consumer would have the choice of using a mixture of lighting and low wattage appliances as long as the total does not exceed the pre-set amount. Thus during peak times consumers would have some choice on the use of appliances, e.g. televisions, etc.

iii) using microprocessor devices to alter the tariff structure during the day so that the cost reflected the marginal cost of generating electricity at that time of day. By some display the consumer would know the tariff rate at any particular time and would thus be encouraged financially to minimise his demand at peak times (this has also been covered in 10.4.5 above).

While these give examples of what could be done technically the economic and social implications must also be considered. Clearly consumers who opt for a scheme such as the Florida Power scheme


or (i) or (ii) above will expect a rebate. Whether the size of the rebate could be made economically attractive to the consumer remains to be seen. The cost of such schemes can be offset against the cost of constructing additional new plants to meet the peak demand. However, in most cases they will defer the construction rather than remove a need altogether because of potential growth as outlined in section 10.7.

10.6 Other methods to reduce demand.

It has been seen that television scheduling can have a drastic effect on sudden peak demand. Rescheduling TV programs, particularly those with adverts such that there are more advert at the beginning of the program say in the north at the start of a program and less in the south will mean that a network screened film, for instance may be running say 3 -4 minutes earlier in the south than the North. By having more adverts in the south at the end to compensate, the extent of the surge in demand at commercial breaks etc can be significantly reduced.

In the UK, most consumers pay for their energy quarterly in arrears. This means that the "expensive" winter bills arrive when the temperature is warmer while the "cheaper" autumn bills arrive during the peak demand for energy. This will tend to send the wrong message to the consumers interested in saving energy as the billing period is divorced from the period of actual use. The situation is made worse since alternate bills are now estimate rather than actual ones. Further the discounts offered to pay by direct debit means that charges are constant through the year and there is no indication of exactly how energy is being used unless the consumer is conscientious in keeping records. In a car we are reminded frequently of how we are using energy by the need to fill up on a weekly or fortnightly basis. In days gone by, we had the same message from the number of buckets of coal we had to bring in to keep warm.

Perhaps we need a scheme with a SMART card and slot. In this a warning (light or audible) would be given when a quantity of energy had been used and it will be necessary for us to swipe the card through to continue to consume energy. We could still retain the option of paying by direct debit or quarterly in areas, but there would then be the reminder of exactly how we are using electricity.

10.7 Increase in electricity Consumption following Fuel Switching

There are many applications where energy consumption in the form of electricity is often as low as one fifth or even one tenth the consumption required using an alternative fossil fuel such as gas. Electricity scores in this respect in cases such as drying - the air-knife, dehumidification, case hardening etc.

Often applications using infra red heating or radio frequency heating can target heating to places where it is need rather than heating up large volumes of confining spaces. In other cases the extra control provided by electrically driven furnaces etc leads to shorter warm up times, and in some cases very short warm up times can be employed.

When savings in delivered energy from electricity use are greater than about 2:1 to 2.5:1 over a fossil fuel, then there will be a net saving in fuel reserves even though this will lead to an increase in electricity consumption (and the consequent need for additional power stations). The exact value at which electricity use actually saves energy depend on the ratio of the primary energy to useful energy in the two situations taking into account the full working cycle (including warm-up).

Three other key areas of potential electricity growth are:-

· installation of heat pumps· change to electric vehicles (environmental considerations)· consequences of a continued reduction in household size -

hence more consumers

All of these would represent a growth in the demand for electricity, the first two would be substantial.

The evidence is strong that there will be an increase in total electricity consumption. Savings through technology and improved management are unlikely to offset the rise in demand from other areas. Following a nearly static demand between 1973 and 1985 there has been a consistent 1.8% annual increase in demand in the last 20 years with no signs that this is reducing. It is probable that a similar growth with continue for a few years at least and present Government projections put the demand of electricity in 2010 about 10% higher than currently. This means that if the Government aims to generate 10% of electricity by renewables by then all this will do is to cope with the increase in demand and will do nothing to reduce CO2 emissions.

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