In calculating RDA for a particular nutrient, 2 SD are not added for
Recommended Dietary Allowance (RDA): Is a level of intake corresponding to Mean + 2 Standard Deviation, which covers requirement of 97.5 % of population

RDA is safe level of intake which is likely to be inadequate in not more than 2.5 % population
RDA 'safe level approach' is NOT USED FOR ENERGY since excess energy intake is undesirable; For energy only mean or average requirement is defined as RDA.
Iron
Calcium
Energy
Vitamin A