Model (1) is the authors' optimal/preferred model (strongest rejection of linearity, real-GDP threshold); its first-regime own-price coefficient (-0.233) is the headline value repeatedly emphasized (Table 5 all-countries avg maintains ~-0.229) || 'the optimal model would be Model (1)' (p.899); 'The own price elasticity of electricity demand is also inelastic and maintains roughly -0.229' (p.901)
Lee, C.-C., and Y.-B. Chiu (2011): "Electricity Demand Elasticities and Temperature: Evidence from Panel Smooth Transition Regression with Instrumental Variable Approach." Energy Economics 33(5), 896-902