The proposed method for assessments of additional thermal insulation measures is based on a simplified interdisciplinary assessment approach, where only four aspects are considered; the materials consumption, the energy consumption, the emissions to air and the total economic costs. The final assessment is based on the economic profitability of the measures.
Even though it may seem preferable to include a large number of interdisciplinary issues in the assessment, such comprehensive assessments are seldom performed. One reason for this may be that it is not relevant or important for the overall assessment to include many issues. Another reason may be that there is a lack of available information on some of the issues. Further, an increased number of interdisciplinary issues included in the assessment consequently also increases the problems of weighting the relative importance of the different issues, as well as it makes the assessment more time consuming and thus costly to perform.
5.3.1 Relevance of the issues included in the proposed assessment
method
For the assessment of alternative additional thermal insulation measures that may be performed in Norwegian houses, the most important environmental issues may be assumed being the energy consumption and the emissions to air from fuel combustion. The energy consumption and the emissions to air of CO2, SO2, NOx and PM are
therefore included in the assessment. In addition, also the materials consumption and the total economic costs associated with the additional thermal insulation measures are included as explained in the following.
Materials account
The materials account is probably the account of least importance for the overall
assessment of additional thermal insulation measures. The reason for this is that scarcity of resources may not be used as an argument against the use of the most common
building materials required; namely mineral wool, wood and plaster. Energy account
In the energy account, the consumption of electricity, fuel oil and firewood are taken into account. Since it is easier to discuss the energy consumption referring to one single
energy parameter, the total energy consumption only is often stated. Also, since the use of one energy source in many cases may be substituted by the use of another energy source, it is not of large importance for the overall assessment which energy source is used. For the emissions to air, however, the type of energy used is of large importance.
Emissions account
The emissions to air taken into account in the assessment are emissions of CO2, SO2, NOx and PM. These emissions are all considered being harmful to the environment. There are abatement goals in Norway for the emissions of CO2, SO2 and NOx (see Appendix A), while there are no targets for the emissions of PM. CO2 is the most important anthropogenic greenhouse gas and the emissions of CO2 thus have global consequences. The emissions of SO2 and NOx, which are important sources for acid rain, have regional consequences. In addition, NOx emissions contribute to the formation of photo chemical oxidants which is also a regional problem.
The emissions of particulate matter (PM) have local consequences. PM10, which are defined as particles smaller than 10 mm, are inhaled far down into the respiratory passages. Small particles contain a large share of toxic substances, such as polycyclic aromatic hydrocarbons (PAHs) having carcinogenic effects. Particles also represent an aesthetic problem (Miljøverndepartementet, 1994). However, uncertainties are involved in the information on PM10 gathered from various sources. For instance, statistics performed by Statistics Norway refer to PM resulting from combustion processes only, and do not consider asphalt dust from road traffic or PM originating from industrial processes. In addition, it is also often uncertain whether data on emissions of PM refer to PM10 only, or include larger particles. Large uncertainties may therefore be involved
when using data on emissions of particulate matter from different sources. In the assessment, emissions of PM are taken into account since wood-firing in households is the main contributor to the total emissions of PM in Norway.
Economic account
Economic aspects are very important for additional thermal insulation measures since the profitability often is the main reason for these measures to be performed. Another reason for the importance of economic aspects is the fact that economic instruments based on the "Polluter-Pays-Principle" are the main instruments of the environmental policy in
Norway. Consequently, economic aspects enter into as a natural part of environmental assessments of energy saving measures in houses.
5.3.2 Discussion of the weighting procedure used in the proposed
assessment method
In the proposed assessment method, the final evaluation of the additional thermal
insulation measures is based on the economic profitability of the measures. Consequently, the weighting of the different issues is based on the monetary value of the issues. In this weighting part, no efforts are made to quantify the real economic value of the
environmental effects associated with the additional thermal insulation measures. Instead, it is possible to include the effect on the profitability of for instance increased energy prices and enhanced emission charges on environmentally harmful gases. Thus, the proposed assessment method is more an economic assessment method where the effect of environmental taxation ("green taxation") can be included, rather than an environmental assessment method.
One reason for basing the final evaluation on the economic profitability, and thus the weighting on monetary valuation, is that the Norwegian Government is basing the environmental policy on economic instruments and the "Polluter-Pays-Principle". It is therefore important to study how the application of various economic instruments will influence on the profitability of additional insulation measures.
Another, more pragmatic reason for basing the final evaluation on the economic
profitability, is the simple fact that there at present (1995) exists no generally accepted method for weighting the importance of interdisciplinary issues. The reason for this is that the importance of different issues often is perceived differently, both by individuals and by societies. This element of subjectivity involved in the weighting step in the assessment methods, is therefore a constantly recurring problem for the development of generally accepted interdisciplinary assessment methods.
A brief survey on environmental policy instruments, life cycle analysis methods and monetary valuation techniques, is presented in Appendix B.
5.3.3 Description of some relevant issues not included in the proposed
assessment method
The proposed assessment method focuses on energy consumption, emissions to air and economic costs. A large number of other issues, however, could have been included in the assessment method. Examples of such issues are social, technical, aesthetic and political effects, as well as a vast number of other environmental effects. For several reasons, these issues are not included. In the following, some issues and effects that could have been included in the assessment are listed with the reason for not including them. A large number of other environmental issues than global warming (CO2), acidification (SO2 and NOx), formation of photo chemical oxidants (NOx) and local air pollution (PM) could have been included in the method. For additional thermal insulation measures, however, most of the other issues may be regarded being of limited importance and thus not included. Lack of data is another reason for not including some of the issues.
Examples of environmental issues neglected because of lack of data, are emissions to ground and water resulting from the depositing of building waste materials on disposal sites.
Indoor climate effects are not included in the assessment, even though additional thermal insulation measures may be expected to have some influence on the indoor climate. The air leaks may be reduced since the air-tightness of the building envelope is often
improved as a result of the insulation measures. The thermal comfort of the inhabitants may also increase as a result of increased indoor surface temperatures of the improved outer constructions, and a more uniform temperature distribution may be attained within the improved house. Also the sound insulation of the outer constructions may be
improved. However, it is difficult to quantify the overall effect on the indoor climate of additional insulation measures, and therefore indoor climate effects are neglected in the assessment.
Technical issues, such as durability factors influencing the service life of the improved constructions, could have been included. But, they are regarded of minor importance for the overall assessment, as well as limited data exist which could have been used.
Technical issues are therefore not considered.
Aesthetic issues can be important for refurbished façades since the appearance of the building may be notably affected by the additional thermal insulation measures. However, these issues are very difficult to quantify and therefore not included in the assessment.
Political issues could have been included since the energy consumption and the
environmental load from the residential sector, as well as the energy prices households have to pay, are important political questions. However, political issues are almost impossible to include in quantitative assessments, and therefore not included in the assessment.