The main objective of this paper is to examine how exogenous technological progress, in terms of an increase in energy efficiency, affects consumption choice by Swedish households and thereby emissions of IMF carbon dioxide (CO2), sulphur dioxide (SO2) and nitrogen oxide (NO chi). The aim of the paper is closely related to the discussion of what is termed the "rebound effect''. To neutralise the rebound effect, we estimate the necessary change in CO2 tax, i.e. the CO2 tax that keeps CO2 emissions at their initial level. In addition, we estimate how this will affect emissions of sulphur dioxide and nitrogen oxides. The results indicate that an increase in energy efficiency of 20% will increase emissions Of CO2 by approximately 5%. To reduce the CO2 emissions to their initial level, the CO2 tax must be raised by 130%. This tax increase will reduce the emissions of sulphur dioxide to below their initial level, but will leave the emissions of nitrogen oxides at a higher level than initially. Thus, if marginal damages from sulphur dioxide and nitrogen dioxide are non-constant, additional policy instruments are needed. (c) 2006 Published by Elsevier B.V.