A microencapsulated phase change material comprising a particle comprising a core material and a wall material that surrounds the core material, wherein said particle's core material comprises 50 to 97 wt% of a methyl ester derived from palm oil and from 0.1 to 20 wt% of a straight chain alkane based on total weight of the core, and wherein the core additionally includes from 0.1 to 25 wt% of a wax, wherein the wax is selected from the group of waxes consisting of polyethylene wax, carnauba wax, candelilla wax, vegetable wax, beeswax and paraffin wax; the particle having a Thermal Efficiency Index (TEI) greater than 0 when measured using the methods provided in the description, wherein the TEI is defined as: TEI = α RΔT ∗ β RΔH ∗ γ RMP ∗ δ R T G A @ 180 ∗ ∈ RFW where: α = constant weighting for RΔT (=20), β = constant weighting for RΔH (=10), γ = constant weighting for RMP (=5), δ = constant weighting for RTGA @180 (=20), ε = constant weighting for RFW (=15), RΔT = rating for the difference between the peak temperatures on the melting and crystallization curves (0 to 1, <10°C); the rating is based on a sliding inverse scale of 0 to 1 assigned on the basis of 0 for Delta T greater than 10°C, and 1 for a Delta T of 0°C, RΔH = rating for melting latent heat (0 or 1, >165 J/g); a value of 1 is assigned if the latent heat is at least 165 Joules per gram, and a value of 0 is assigned if less than 165 Joules per gram, RMP = rating for peak melting temperature; a value between 0 and 1 is assigned based on a value of 1 at 28.5°C; the range is 27°C to 30°C for values between 0 to 1; the assigned value is based on the position in the stated range and relative difference from 28.5°C, expressed as a fraction from 1 to 0 starting with 28.5°C as a value of 1; above or below this range a value of 0 is assigned, RTGA @180 = rating for percent weight remaining at 180°C; a value between 0 and 1 is assigned based on 0 for 94% or less remaining; 1 for 96% or greater remaining; and 0 to 1 for the range 94% to 96%, and RFW = rating for free wax (core) (0 to 1, <3%); a value between 0 and 1 is assigned based on 0 to 1 for free wax of less than 3% where a value of 1 indicates no free wax detected. α = constant weighting for RΔT (=20), β = constant weighting for RΔH (=10), γ = constant weighting for RMP (=5), δ = constant weighting for RTGA @180 (=20), ε = constant weighting for RFW (=15), RΔT = rating for the difference between the peak temperatures on the melting and crystallization curves (0 to 1, <10°C); the rating is based on a sliding inverse scale of 0 to 1 assigned on the basis of 0 for Delta T greater than 10°C, and 1 for a Delta T of 0°C, RΔH = rating for melting latent heat (0 or 1, >165 J/g); a value of 1 is assigned if the latent heat is at least 165 Joules per gram, and a value of 0 is assigned if less than 165 Joules per gram, RMP = rating for peak melting temperature; a value between 0 and 1 is assigned based on a value of 1 at 28.5°C; the range is 27°C to 30°C for values between 0 to 1; the assigned value is based on the position in the stated range and relative difference from 28.5°C, expressed as a fraction from 1 to 0 starting with 28.5°C as a value of 1; above or below this range a value of 0 is assigned, RTGA @180 = rating for percent weight remaining at 180°C; a value between 0 and 1 is assigned based on 0 for 94% or less remaining; 1 for 96% or greater remaining; and 0 to 1 for the range 94% to 96%, and RFW = rating for free wax (core) (0 to 1, <3%); a value between 0 and 1 is assigned based on 0 to 1 for free wax of less than 3% where a value of 1 indicates no free wax detected. <EOS>