5.– DIFERENTES PROPUESTAS PARA LLEVAR EL JUEGO TRADICIONAL A LA CLASE DE EDUCACIÓN

Figures 10.2 and 10.3 illustrate the delivered energy use and CO₂ emissions attributable to the UK housing stock under each of the scenarios. The results show that by the year 2050, considerable reductions in delivered energy use and CO₂emissions are expected to occur

within all of the scenarios. All of these reductions are expected to occur despite a number of opposing trends.

These trends include a substantial increase in the total number of UK households; an increase in thermal comfort standards; and a substantial increase in the ownership and usage of central heating systems and various electrical appliances.

The scale of the projected reductions in delivered energy use and CO₂emissions varies between each of the scenarios (see Figures 10.2 and 10.3). Under the business as usual scenario, which assumes a continuation of current trends, building fabric improvements, increases in end-use efficiency and a continued reduction in the carbon intensity of electricity generation result in a 21 per cent and a 33 per cent reduction in delivered energy use and CO₂ emissions, respectively, by the middle of this century.

These reductions in delivered energy use and CO₂ emissions could be reduced by a further 29 and 25 percentage points, respectively, if the current rate at which fabric and end-use efficiency measures are being implemented in the demand side of the UK housing stock are increased to the levels that have been identified within the demand side scenario. Figure 10.3 also illustrates that a further 7 percentage point

0 500 1000 1500 2000 2500

1995 2005 2015 2025 2035 2045

Year

Delivered energy use (PJ)

'Bus ines s -as -Us ual' s c enario

'Demand Side' & 'Integrated' s c enario

Figure 10.2 Total delivered energy use attributable to the developed scenarios over the period of 1996 to 2050

reduction in CO₂ emissions could be achieved if various measures are also applied to the electricity generation side of the energy supply sector.

The CO₂ emission trajectories of all three illustrative scenarios have also been compared against the UK’s Kyoto Protocol target of a 12.5 per cent reduction in CO₂emissions between 2008 and 2012, the UK government’s domestic target of a 20 per cent reduction in CO₂emissions by 2010 (DETR, 2000), and the UK government’s Energy White Paper target of a 60 per cent reduction in CO₂ emissions by 2050 (DTI, 2003). Relative to the 1990 baseline,²Figure 10.3 indicates that although all of the scenarios are likely to achieve the UK’s Kyoto target, only the demand side and the integrated scenario are likely to achieve the UK government’s domestic target. More importantly, the results also suggest that the Royal Commission on Environmental Pollution (RCEP) target of a 60 per cent reduction in CO₂ emissions by the year 2050 could be achieved under both the demand side and the integrated scenarios. However, achieving these sorts of emission reductions will require a considerable increase in the current uptake rate of efficiency measures within both the demand side and the supply side of the UK housing stock.

Conclusions

This case study has described the development of DECARB, a selectively disaggregated physically based bottom-up energy and CO₂emission model of the UK housing stock and illustrates how this model has been used to explore the technical feasibility of achieving CO₂emission reductions in excess of 60 per cent within the UK housing stock by the middle of this century.

This has been achieved by constructing and evaluating three illustrative scenarios for this sector – namely, a

‘business as usual’ scenario, which represents a continuation of current trends in fabric, end-use efficiency and carbon intensity trends for electricity generation; a ‘demand side’ scenario, which represents what may happen if the current rate of uptake of fabric and end-use efficiency measures were to be increased;

and an ‘integrated’ scenario, which shares the same demand-side assumptions as the ‘demand side’ scenario, but represents what may happen if the carbon intensity of electricity generation were to fall even further.

The scenario results indicate that it is technically feasible, using currently available technology, to achieve the sorts of CO₂emission reductions that are likely to be required to stabilize atmospheric CO₂concentrations Figure 10.3 CO₂emissions attributable to the developed scenarios over the period of 1996 to 2050

0 20 40 60 80 100 120 140 160

1995 2005 2015 2025 2035 2045

Year

'Business-as-Usual' scenario 'Demand Side' scenario 'Integrated' scenario CO2 emissions (million tonnes CO2)

and to mitigate the effects of climate change under the demand side and integrated scenarios. These reductions appear feasible despite a substantial increase in the total number of UK households, an increase in thermal comfort standards and a significant increase in the standards of service that occupants are likely to expect.

However, achieving these sorts of emission reductions will be technically demanding and will require a considerable increase in the current rate of uptake of energy efficiency measures within both the demand side and the supply side of the UK housing stock.

Notes

1 In this context, dwelling types refer to a very broad range of dwellings, rather than to dwellings of a particular size, form, tenure or age-related category.

2 The year 1990 has been used as a baseline as it is commonly referred to in climate change scenarios.

References

DETR (Department of Environment, Transport and the Regions) (1996) English House Condition Survey 1996 Energy Report, DETR, London

DETR (1998) The Government’s Standard Assessment Procedure for the Energy Rating of Dwellings, DETR, London

DETR (2000) Climate Change: The UK Programme – Summary, DETR, London

Dickson, C. M., Dunster, J. E., Lafferty, S. Z. and Shorrock, L. D. (1996) ‘BREDEM: Testing monthly and seasonal versions against measurements and against detailed

simulation models’, Building Services Engineering Research and Technology, vol 17, no 3, pp135–140

DTI (Department of Trade and Industry) (2003) Energy White Paper: Our Energy Future – Creating a Low Carbon Economy, DTI, HMSO, London

IEA (International Energy Agency) (1998) Mapping the Energy Future: Energy Modelling and Climate Change Policy, Energy and Environment Policy Analysis Series, IEA/OECD, Paris, France

Johnston, D. (2003) A Physically-Based Energy and Carbon Dioxide Emission Model of the UK Housing Stock, PhD thesis, Leeds Metropolitan University, UK

MIT (Massachusetts Institute of Technology) (1997) Energy Technology Availability: Review of Longer Term Scenarios for Development and Deployment of Climate-Friendly Technologies, MIT Energy Laboratory, Cambridge, Massachusetts, US

Shorrock, L. D. (1994) Future Energy Use and Carbon Dioxide Emissions for UK Housing: A Scenario, BRE Information Paper IP9/94, Building Research Establishment, Garston, Watford, UK

Shorrock, L. D. and Dunster, J. E. (1997) ‘The physically-based model BREHOMES and its use in deriving scenarios for the energy use and carbon dioxide emissions of the UK housing stock’, Energy Policy, vol 25, no 12, pp1027–1037 Shorrock, L. D., Macmillan, S., Clark, J. and Moore, G.

(1991) ‘BREDEM 8: A monthly calculation method for energy use in dwellings: Testing and development’, in Building Environmental Performance 1991, University of Kent, Canterbury, 10–11 April 1991, BEPAC, London Shorrock, L. D., Henderson, J., Utley, J. L. and Walters, G. A.

(2001) Carbon Emission Reductions from Energy Efficiency Improvements to the UK Housing Stock, BRE Report 435, Building Research Establishment, Garston, Watford, UK

Introduction

The challenge that building stock poses in the face of climate change urges building professionals in many countries across the globe to renovate existing stock with sustainability and energy efficiency in mind.

Around 30 to 40 per cent of worldwide primary energy is used in buildings (UNEP, 2007) and space heating and domestic hot water services are taking up a considerable share of almost 75 per cent (WWF, 2008).

It is expected that an existing home requires four times as much energy for heat as does a new home (DTI, 2007). One of the few industrialized countries in which CO₂ emissions have been reduced since 1990 is Germany. A considerable share of savings made in Germany in recent years can be attributed to the national climate protection programme under which credit programmes were launched in October 2000 for renovating existing buildings. Along with other policies, these programmes will allow Germany to meet a 54 per cent reduction in CO₂emissions of 1990 levels by the year 2030. The overall aim is to reduce the CO₂ emissions from 1990 to 2050 by 80 per cent. The KfW CO₂Building Rehabilitation Programme proved to be Germany’s most effective element of the national climate protection programme for existing housing stock. The two most effective components within this programme are (UBA, 2008):

1 retrofitted external insulation of existing buildings;

2 replacement of boilers with new high-efficiency heating systems.

These findings were confirmed by recent research in the UK (Lowe, 2007). However, relevant incentives or programmes to deal with these issues have yet to be introduced in most countries of the European Union.

As of today, the trend in the UK, for example, is towards higher energy consumption, the energy delivered to UK dwellings, for example, has increased by 30 per cent over the last 30 years (Oreszczyn and Lowe, 2005).

The aim of this case study is therefore to investigate the effects of German climate change policy on the reduction of carbon emissions from existing dwellings.

Most countries urgently need efficient ‘tried and tested’

policy tools to tackle the effects of climate change. The first part of this case study reviews the policy landscape in Germany, and the second part investigates the German CO₂ reduction programme in practice. The latter consists of a detailed calculation of the energy consumption for space heating and domestic hot water services of a building. The trends of the change in energy demand and the associated carbon emissions indicate the effectiveness of technical interventions and the efficiency of relevant policy instruments.