Abstract headlines the long-run estimates, no preference between Eqs.(1)/(2), both ~-0.35 || "Estimates of the long-run income and price elasticities are 1.0 and -0.35, respectively." (Abstract p.37)
Ang, B.W., T.N. Goh, and X.Q. Liu (1992): “Residential Electricity Demand in Singapore.” Energy 17(1), 37-46