Energy efficiency and the challenge of climate change - Studies of the Swedish building sector

The interrelated environmental, social and economic challenges imposed by global climate change will make it one of the central political issues in the coming century. Use of fossil fuels is the largest source of anthropogenic CO2 emissions and hence the transformation of the energy system plays a central role in the mitigation of future climate change. While the energy debate is often focused on changes on the supply side of the energy system, scenarios indicate that changes on the demand side are equally important for future abatement of CO2 emissions. The building sector is very important in terms of primary energy use and contains major potentials for energy efficiency improvements. However, the slow replacement of the building stock requires long time perspectives in energy policy in order to utilize these potentials. This thesis consists of three papers with the Swedish building sector as the common object. The first paper analyses the development in the Swedish building sector over time by decomposing CO2 emissions in underlying trends, and looking at separate energy use trends for existing buildings, new- construction and best available technology. The results show that the improvements in energy efficiency stagnated in both existing buildings and new-construction in the late eighties and nineties, and that the diffusion of energy efficient technologies appears to be slow. The specific energy use for heating in mainstream new-construction is twice as high as in the best performing buildings 20 years ago. The second paper addresses two central questions from the first paper: Why has the development towards improved energy efficiency stagnated, and what are the causes of the slow adoption of energy efficient technologies in the building sector? Two methods are used: econometric analysis to quantify the explanatory value of energy prices and income trends, and a qualitative analysis based on interviews. The results show that declining specific energy use for heating has a high correlation with increasing energy prices and that the price elasticity has not changed markedly over time. This implies that the stagnation to a large extent can be explained by energy price trends. The paper also points to potential organisational barriers to energy efficiency as well as weaknesses in the learning processes in the building sector. The third paper is based on an input-output analysis of primary energy use and CO2 emissions from the production of buildings. The aim is to disaggregate top-down results into activities and materials which can be compared to results from bottom-up studies. The results show only minor differences for production and processing of building materials, while for other upstream sectors such as transports, production of machines and services sectors, the input-output-analysis gives much higher values. Some of these differences can be explained by truncation errors due to the definition of system boundaries in bottom-up studies. Truncation errors may imply underestimations of the relative importance of energy use in the production phase, since the use phase is dominated by more easily estimated direct energy use