1. A method for collaborative building a shared self-refining surrogate model for engineering simulations in a computer network, comprising: receiving, by a unified service module of a remote server via the computer network, a request for a higher order simulation of a reduced order simulation item from a reduced order engineering simulation model running on a client device, wherein the client device runs the reduced order engineering simulation model to simulate one or more simulation items of a complex system, wherein the higher order simulation is a three dimensional (3D) simulation and the reduced order simulation item is a one dimensional (1D) simulated element; determining, by the unified service module, whether a required higher order simulation result, within a confidence interval required for the reduced order simulation item, is in the shared self-refining surrogate model residing in the remote server, wherein the shared self-refining surrogate model comprises previously performed higher order simulations and results associated with the previously performed higher order simulations; and if not, performing the higher order simulation to obtain the required higher order simulation result within the confidence interval required for the reduced order simulation item by the unified service module, enriching the shared self-refining surrogate model with the obtained higher order simulation result by the unified service module, and sending the obtained higher order simulation result to the reduced order engineering simulation model via the computer network by the unified service module.