Solid-state cooling technology based on the electrocaloric effect (ECE) is attracting increasing attention as an important alternative for traditional cooling systems because of its advantages of high efficiency, environmental friendliness, lightweight, low cost and easy miniaturization. Ferroelectric materials are suitable candidates for ECE refrigeration due to their large polarization and entropy change through applying or removing an external electric field. Recently, studying on the ECE of lead-free bulk ceramics has become one of the hot topics in ferroelectric community due to the requirements of sustainable development. In this project, systematic study on the ECE in BaTiO3-based and 94%Bi0.5Na0.5TiO3-6%BaTiO3 based lead-free bulk ceramics were carried out through an indirect method based on Maxwell relations. The secondary electrocaloric effect (ECE) arising from piezoelectricity combined with crystal thermal expansion was often overlooked in ECE studies of ferroelectric ceramics. This work evaluated the primary ECE (∆TECE) and secondary ECE (∆T2) of eco-friendly BaSnxTi1-xO3 (BSnT100x, 0< x <12%) ceramics near the tetragonal (T)-orthorhombic (O) transition. Intriguingly, a maximum overall ∆T ~0.85 K was obtained at the T-O transition (~300 K) of BSnT2 under an electric field of 2 kV/mm, with ∆TECE and ∆T2 amounting to ~0.75 K, ~0.1 K, respectively. This ECE result is ~40% superior than the larger ECE reported previously for BSnT system. Furthermore, the inverse (or negative) electrocaloric effect (ECE) was found in increasing amount of ferroelectric materials. In theory, the combination of conventional and inverse ECE in one cooling cycle offers great prospects for highly efficient and environmentally friendly engineering refrigeration solutions. But it is still challenging to effectively modulate the sign of ECE in a single ferroelectric system in practice. In this work, the sign of ECE at 300 K in 94%Bi0.5Na0.5TiO3-6%BaTiO3 ceramics can be modulated from negative to positive by the increase of Mn doping level due to the synergistic effects of polar nano-regions (PNRs) and defect dipoles. Furthermore, the negative secondary ECE at room temperature can be disregarded in Mn-doped 94%Bi0.5Na0.5TiO3-6%BaTiO3 ceramics due to their weak piezoelectric constants and low thermal expansion. This work indicates the sign of ECE can be modulated by appropriate amount of doping and the secondary ECE cannot be disregarded for ferroelectrics with high piezoelectric responses and large thermal expansions. This work opens up the possibility of changing the sign of ECE in ceramics through doping and gives rise to the hope that cooling performance can be improved by using a combination of positive and negative ECE in a single material system.