However, the subjective nature of establishing baselines means that choices of baselines can vary widely (see e.g. Clapp et al., At a project or portfolio scale, analysis has highlighted that estimated emissions reductions can vary by a factor of three for renewable energy and more than a factor of ten for energy efficiency projects across different MDBs carbon foot-printing tools (Bossard, 2012, pers. The wide variation in assumptions and models to establish baselines will lead to wide differences in the estimated results of an intervention when compared to that baseline.