ارزش قائل شدن برای پیشرفت ها در راحتی از موهبت بازبینی بهره وری انرژی داخلی با استفاده از یک مدل شبیه سازی تجارت کردن

There are a number of stimuli behind energy efficiency, not least the Kyoto Protocol. The domestic sector has been highlighted as a key potential area. Improving energy efficiency in this sector also assists alleviating fuel poverty, for research is now demonstrating the strong relationship between poor domestic thermal efficiency, high fuel poverty and poor health and comfort status. Previous research has modelled the energy consumption and technical potential for energy saving resulting from energy-efficiency upgrades in this sector. However, there is virtually no work evaluating the economic benefit of improving households’ thermal comfort post-retrofit. This paper does this for Ireland using a computer-simulation program. A dynamic modelling process is employed which projects into the future predicting the extent to which energy savings are forgone for improvements in comfort.

The impetus to conserve energy comes from a variety of sources. In recent times, the Kyoto Protocol has been the most prominent in bringing energy efficiency to the fore. In some countries, the domestic sector has been highlighted as an area which has a significant potential for improvement. A key issue strongly linked with energy (in)efficiency in this sector, particularly in western Europe, is that of fuel poverty.1 Research is beginning to show the tangible relationship between low levels of domestic thermal efficiency, high rates of fuel poverty and reduced health and comfort status (Clinch and Healy, 1999), the end result of which can be premature mortality (Clinch and Healy, 2000a and Rudge and Nicol, 2000). Evidence from studies around the world continues to support the hypothesis that energy-efficiency measures and programmes result in highly cost-effective investments, using even the narrowest criteria. The early work of Pezzey (1984) and later research by Henderson and Shorrock, 1989 and van Harmelen and Uyterlinder, 1999, show the clear net benefits of individual retrofitting technologies. At the macro level, Arny et al., 1998, Brechling and Smith, 1994, Clinch and Healy, 2001 and Goldman et al., 1988 demonstrate the benefits of comprehensive retrofitting programmes. However, the energy-assessment models upon which energy-efficiency studies are based vary in quality and reliability. In addition, the scope of the economic analysis is almost always narrow—typically just evaluating the costs and benefits in terms of reductions in energy consumption and attendant environmental emissions. There are a number of papers in the literature of energy economics that attempt to model both the energy consumption and technical potential for energy saving in the domestic sector resulting from energy-efficiency improvements; in northern Europe, such energy benefits arise from reduced energy use in heating the home.2 Such research has been carried out in Australia by Michalik et al. (1997), in Belgium by Hens et al. (1998), in Denmark by Jacobsen (1998), in Spain by Cuchi (1998), in Taiwan by Yang and Su (1997), in the UK by the Building Research Establishment, 1998 and Jaggs and Palmer, 2000, and in the USA by Hoffman and Jorgenson, 1977 and Holz et al., 1997. However, there is virtually no research which places an economic value on the improvement in comfort that results from such retrofitting exercises. This paper does this for Ireland using a computer-simulation model, the precise details of which are given in Clinch et al. (2001). A feature of many domestic energy-assessment models is that they assume that private benefits from energy-efficiency programmes will take the form of reduced energy bills, while external benefits may include reductions in environmental emissions. If it is assumed that all dwellings are heated to a safe and comfortable temperature, this assumption is reasonable. However, if a portion of the housing stock has sub-optimal levels of warmth, a domestic energy-efficiency programme is likely to result in some of the energy savings (predicted on the basis of fixed internal temperatures) being forgone in exchange for increased internal temperatures. A key feature of this research is that a dynamic modelling process was used to project into the future to predict the extent to which energy/emissions’ savings might be forgone in exchange for improvements in comfort/health. The article is structured as follows. The next section briefly outlines the retrofitting programme and the policy context for energy efficiency in Ireland. The subsequent section provides a discussion of comfort and how it is defined in this study. The physiological requirements for thermal comfort are also outlined. This section is then followed by a brief description of the energy-assessment model, its key inputs and outputs. The dynamic modelling process is explained in the subsequent section and the trade-off approach is outlined. Furthermore, the section explores how the ‘bottom-up’ and ‘top-down’ approaches to energy-assessment modelling are consolidated in this model. In Section 5, the methodology is described for calculating the portion of benefits of the retrofit taken as improved thermal comfort. The physical results (in terms of improved household temperatures) are compared with those found in existing literature that measure the impact of energy-efficiency improvements on increased household warmth. The proceeding section presents the monetary results of the model regarding comfort and a sensitivity analysis is conducted. An indication of the corresponding economic benefit for British housing is also derived by way of comparison. The final section proffers some conclusions and policy recommendations.

This article has modelled and valued the improvements in thermal comfort which arise as a result of an ex ante energy-efficiency retrofitting programme in Ireland. A key feature of this research is that a dynamic modelling process was required which could be used to project into the future to predict the extent to which energy/emissions’ savings might be forgone in exchange for improvements in comfort/health, and, as such, the model illustrates the trade-off households face after energy-efficiency retrofits. One of the model's strengths is that it implements a convergence of ‘bottom-up’ and ‘top-down’ modelling approaches. By adjusting parameters in order to give the best match between data from the two approaches, accuracy is optimised given the information available. The improvements in thermal comfort were valued using a proxy inherent in the computer-simulation model. The proxy let the proportion of energy savings foregone over the programme's 20-year life (i.e. the proportion of maximum, potential energy savings not realised) equal households’ implicit willingness to pay to increase the warmth of their dwelling to a thermally comfortable temperature. This approach assumes some degree of knowledge on the part of the householder regarding this trade-off and is lower bound by nature, as the results do not necessarily reflect households’ maximum willingness to pay for increased thermal comfort. Notwithstanding this somewhat conservative approach, the monetary results are substantial, at €461 million discounted at 5% over 20 years. Furthermore, the physical results—in terms of the predicted increase in average household temperatures once the programme has been completed—are also striking: a mean increase of 2.9 °C from 14.8 to 17.7 °C is anticipated by the simulation model. The results of the energy-comfort trade-off demonstrate that comfort benefits account for 21% of total benefits, while energy cost savings represent 79%, broadly in line with the results of a recent ex post study by Milne and Boardman (2000) showing similar proportions for the British housing stock. As the model is based fundamentally on the UK Standard Assessment Procedure, and as the UK has similarly poor domestic energy-efficiency levels (Table 1) and similarly high rates of fuel poverty (Healy, 2003), it is thought useful to present an indicative, ‘scaled-up’ result for the UK. When this is done, a figure of €9973 million is found, highlighting the potential comfort benefits that British households could capture through energy-efficiency improvements. An area for future research relates to some of the assumptions underlying the dynamic component of the model. Rather than assuming that the ‘business-as-usual’ scenario is today's housing stock, the model reflects the likelihood that housing standards will improve, even in the absence of a domestic energy-efficiency programme, due to the adoption of improved insulation, double glazing and so forth during renovations of housing, the replacement of old heating systems at the end of their life with more efficient systems, and the further penetration of natural gas. The assumed number of years it takes for the entire housing stock to become adequately heated can be altered easily in the model for the purposes of sensitivity analysis. The figure used in this paper was estimated using past trends in energy consumption as a proxy for future trends. However, this is a rather simplistic approach and it is likely that, in the absence of a state-led programme, some portion of the housing stock will remain inadequately heated due to some residents being caught in a fuel-poverty trap. The accuracy of the model could be improved and checked by using data from previous years to predict energy consumption of more recent years. This would require the availability of information on trends in the national dwelling stock (for the ‘bottom-up’ approach) and in national energy consumption (for the ‘top-down’ approach) for a number of recent years. Fine-tuning of parameters following such an investigation could increase confidence in the validity of the model's assumptions (including those relating to the convergence of comfort levels with standardised values), and in the accuracy of its predictions. The research documented in this paper is part of a larger economic study which valued an array of programme impacts from the retrofitting exercise outlined here11. The improvements in thermal comfort accounted for 10% of aggregate programme benefits in the economic evaluation. It is clear that both the private and external benefits of such retrofitting schemes are very substantial. However, it is also clear that there are many households who, for a variety of reasons,12 either cannot or do not undertake retrofits. It is, therefore, important to correct this market failure through some form of intervention. The provision of grant schemes to low-income households combined with a thorough information campaign highlighting the cost-effectiveness of energy-efficiency retrofits and minimising transactions’ costs should be undertaken by the State. Failure to act will entail that individuals will continue to inhabit cold, uncomfortable housing, resulting in ill-health and, at worst, premature death.